tag:theconversation.com,2011:/us/topics/ocean-energy-11415/articlesocean energy – The Conversation2023-11-06T13:33:51Ztag:theconversation.com,2011:article/2170682023-11-06T13:33:51Z2023-11-06T13:33:51ZHow global warming shakes the Earth: Seismic data show ocean waves gaining strength as the planet warms<figure><img src="https://images.theconversation.com/files/557584/original/file-20231104-23-ehsyya.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C7998%2C5268&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Storm Ciarán pounded England's Newhaven Lighthouse and harbor wall on Nov. 4, 2023.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/BritainEuropeWeather/ca5dffe836424095b080ee781886aa54/photo">AP Photo/Kin Cheung</a></span></figcaption></figure><p>As oceans waves rise and fall, they apply forces to the sea floor below and generate seismic waves. These seismic waves are so powerful and widespread that they show up as a steady thrum on seismographs, the same instruments used to monitor and study earthquakes.</p>
<p>That wave signal has been getting more intense in recent decades, reflecting increasingly stormy seas and higher ocean swell. </p>
<p>In a <a href="https://doi.org/10.1038/s41467-023-42673-w">new study</a> in the journal Nature Communications, colleagues and I tracked that increase around the world over the past four decades. These global data, along with other ocean, satellite and regional seismic studies, show a decadeslong increase in wave energy that coincides with increasing storminess attributed to rising global temperatures.</p>
<h2>What seismology has to do with ocean waves</h2>
<p>Global seismographic networks are best known for monitoring and studying earthquakes and for allowing scientists to <a href="https://doi.org/10.1029/2021RG000749">create images</a> of the planet’s deep interior.</p>
<p>These <a href="https://www.usgs.gov/faqs/seismometers-seismographs-seismograms-whats-difference-how-do-they-work#">highly sensitive instruments</a> continuously record an enormous variety of natural and human-caused seismic phenomena, including volcanic eruptions, nuclear and other explosions, meteor strikes, landslides and <a href="https://eos.org/editor-highlights/small-seismic-signals-tell-a-story-of-iceberg-calving">glacier-quakes</a>. They also capture persistent seismic signals from wind, water and human activity. For example, seismographic networks observed the global quieting in human-caused seismic noise as lockdown measures were instituted around the world <a href="https://theconversation.com/coronavirus-lockdown-reduced-seismic-activity-around-the-world-new-study-143203">during the coronavirus pandemic</a>.</p>
<p>However, the most globally pervasive of seismic background signals is the incessant thrum created by storm-driven ocean waves referred to as the global microseism.</p>
<h2>Two types of seismic signals</h2>
<p>Ocean waves generate microseismic signals in <a href="https://doi.org/10.1002/2014GL062782">two different ways</a>.</p>
<p>The most energetic of the two, known as the <a href="https://doi.org/10.1002/2014GL062782">secondary microseism</a>, throbs at a period between about eight and 14 seconds. As sets of waves travel across the oceans in various directions, they interfere with one another, creating pressure variation on the sea floor. However, interfering waves aren’t always present, so in this sense, it is an imperfect proxy for overall ocean wave activity.</p>
<p>A second way in which ocean waves generate global seismic signals is <a href="https://earthenvironmentcommunity.nature.com/posts/increasing-ocean-wave-energy-observed-in-earth-s-seismic-wavefield-since-the-late-20th-century">called the primary microseism process</a>. These signals are caused by traveling ocean waves directly pushing and pulling on the seafloor. Since water motions within waves fall off rapidly with depth, this occurs in regions where water depths are less than about 1,000 feet (about 300 meters). The primary microseism signal is visible in seismic data as a steady hum with a period between 14 and 20 seconds.</p>
<h2>What the shaking planet tells us</h2>
<p><a href="https://doi.org/10.1038/s41467-023-42673-w">In our study</a>, we estimated and analyzed historical primary microseism intensity back to the late 1980s at 52 <a href="https://www.usgs.gov/programs/earthquake-hazards/gsn-global-seismographic-network">seismograph sites around the world</a> with long histories of continuous recording.</p>
<p>We found that 41 (79%) of these stations showed highly significant and progressive increases in energy over the decades.</p>
<p>The results indicate that globally averaged ocean wave energy since the late 20th century has increased at a median rate of 0.27% per year. However, since 2000, that globally averaged increase in the rate has risen by 0.35% per year.</p>
<figure><img src="https://cdn.theconversation.com/static_files/files/2894/ocean-wave-intensification-since-late-1980s_rick-aster.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=720&fit=crop&dpr=2"><figcaption>Ocean wave intensification since the late 1980s: Each circle is a seismic station, with size proportional to the vertical acceleration of the Earth at that station smoothed over three years. Red circles indicate periods when ground motions are larger than the historical median; blue indicate periods when they are smaller. The synchronized graph shows the median vertical acceleration anomaly for all stations and reflects El Niño cycles and a more pronounced increase in recent years. Source: Rick Aster</figcaption></figure>
<p>We found the greatest overall microseism energy in the very stormy Southern Ocean regions near the Antarctica peninsula. But these results show that North Atlantic waves have intensified the fastest in recent decades compared to historical levels. That is consistent with recent research suggesting <a href="https://wcd.copernicus.org/articles/3/337/2022/0">North Atlantic storm intensity</a> and <a href="https://doi.org/10.1029/2022GL101963">coastal hazards</a> are increasing. <a href="https://apnews.com/article/storm-ciaran-uk-france-winds-climate-61b722101874e7f0610961c03c509229#">Storm Ciarán</a>, which hit Europe with powerful waves and hurricane-force winds in November 2023, was one record-breaking example.</p>
<p>The decadeslong microseism record also shows the seasonal swing of strong winter storms between the Northern and Southern hemispheres. It captures the wave-dampening effects of growing and shrinking Antarctic sea ice, as well as the multi-year highs and lows associated with El Niño and La Niña cycles and their long-range effects on ocean waves and storms.</p>
<figure class="align-center ">
<img alt="Homes hang over the edge of a cliff above an ocean beach." src="https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557585/original/file-20231104-19-p6vlng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In November 2022, Hurricane Nicole’s intense waves eroded the land beneath several homes in Daytona Beach, Fla.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/TropicalWeatherFlorida/29f6d284206848159c921b6b84927799/photo">AP Photo/Rebecca Blackwell</a></span>
</figcaption>
</figure>
<p>Together, these and <a href="https://www.universityofcalifornia.edu/news/californias-winter-waves-may-be-increasing-under-climate-change">other recent seismic studies</a> complement the results from climate and ocean research showing that storms, and waves, are intensifying as the climate warms.</p>
<h2>A coastal warning</h2>
<p>The oceans have absorbed about <a href="https://climate.nasa.gov/vital-signs/ocean-warming/">90% of the excess heat</a> connected to rising greenhouse gas emissions from human activities in recent decades. That excess energy can translate into <a href="https://doi.org/10.1038/s41467-018-08066-0">more damaging waves and more powerful storms</a>.</p>
<p>Our results offer another <a href="https://theconversation.com/dreaming-of-beachfront-real-estate-much-of-floridas-coast-is-at-risk-of-storm-erosion-that-can-cause-homes-to-collapse-as-daytona-just-saw-194492">warning for coastal communities</a>, where increasing ocean wave heights can pound coastlines, damaging infrastructure and <a href="https://www.usgs.gov/science/science-explorer/climate/coasts-storms-and-sea-level-rise">eroding the land</a>. The impacts of increasing wave energy are further compounded by ongoing <a href="https://toolkit.climate.gov/topics/coastal-flood-risk/coastal-erosion">sea level rise</a> fueled by climate change and by subsidence. And they emphasize the importance of mitigating climate change and building resilience into coastal infrastructure and environmental protection strategies.</p><img src="https://counter.theconversation.com/content/217068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Aster receives funding from the U.S. National Science Foundation.</span></em></p>The same instruments used to measure earthquakes pick up vibrations as ocean waves put pressure on the sea floor. Four decades of data tell a story about ocean storms.Richard Aster, Professor of Geophysics and Department Head, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2053192023-05-23T11:14:48Z2023-05-23T11:14:48ZHow we stop floating wind turbines the size of skyscrapers from drifting away<figure><img src="https://images.theconversation.com/files/527507/original/file-20230522-29-juo0z1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4031%2C3024&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hywind Tampen wind farm, Norway.</span> <span class="attribution"><a class="source" href="https://equinor.fotoware.cloud/fotoweb/archives/5020-Press/Folder%201/HYT_offshore1.jpg.info#c=%2Ffotoweb%2Farchives%2F5020-Press%2F">Karoline Rivero Bernacki/Equinor</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Growing demand for cleaner energy sources means offshore wind farms are being built all over the world. <a href="https://www.un.org/sites/un2.un.org/files/2021/09/irena_and_gwec_offshore_wind_energy_compact_-_final_1.pdf">More than 5,000</a> turbines must be installed each year until 2050 to limit global warming to 1.5°C.</p>
<p>But in certain regions, like California, it is difficult to build wind turbines directly on the seafloor due to the <a href="https://theconversation.com/california-is-planning-floating-wind-farms-offshore-to-boost-its-power-supply-heres-how-they-work-163419">steep drop-off of the continental shelf</a>. </p>
<p>Even in areas with shallow coastal waters, such as the North Sea, congestion from shipping lanes, fishing activities, marine protected areas, tourism and existing energy infrastructure all impede new turbine construction. </p>
<p>So it’s hardly surprising that many of these new turbines will have to be located in deeper waters further out to sea. </p>
<p>Floating wind turbines are <a href="https://theconversation.com/floating-wind-farms-how-to-make-them-the-future-of-green-electricity-142847">emerging</a> as a promising solution. But turbines are also getting bigger at a rapid rate – allowing electricity to be produced at a <a href="https://theconversation.com/wind-turbines-are-already-skyscraper-sized-is-there-any-limit-to-how-big-they-will-get-196131">lower cost</a>. </p>
<p>The blades of <a href="https://www.equinor.com/energy/hywind-scotland">Hywind Scotland</a>, the world’s first commercial floating wind farm, tower 175 metres above the sea surface – the same height as the London skyscraper known as The Gherkin.</p>
<p>This represents a huge technical challenge. Located in deep waters, these large floating structures must withstand the relentless push and pull of the ocean while maintaining stability to ensure ongoing energy generation.</p>
<p>So, how do these colossal structures remain in place? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of the four types of floating wind farm platform side by side." src="https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527696/original/file-20230523-29-upa5ii.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The four types of floating wind farm platform.</span>
<span class="attribution"><a class="source" href="https://acteon.com/">Acteon</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>The floating wind turbine</h2>
<p>The mast of a floating wind turbine is connected to a platform, which is designed to provide stability. Several different types of floating platform exist, each with the dimensions of a football pitch.</p>
<p>Beneath the water, mooring lines keep the turbine stable and prevent it from drifting away. Mooring lines can be either very large steel chains or synthetic ropes. Each of the three steel chains used for <a href="https://www.equinor.com/content/dam/statoil/documents/newsroom-additional-documents/news-attachments/brochure-hywind-a4.pdf">Hywind Scotland</a>, for example, are approximately 900 metres long and weigh 400 tonnes. </p>
<p>The mooring lines are attached to the seabed with a ground anchor. Most people will be familiar with anchoring a boat or securing the guy ropes of a tent with pegs. </p>
<p>In both cases, the anchor (or peg) is embedded into the ground, making it harder for the anchor to become dislodged as the weight and strength of the ground has to be overcome to pull the anchor out. The anchors used for floating wind turbines are based on the same principle, but at a far greater scale.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wind-turbines-are-already-skyscraper-sized-is-there-any-limit-to-how-big-they-will-get-196131">Wind turbines are already skyscraper-sized – is there any limit to how big they will get?</a>
</strong>
</em>
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<hr>
<p>Three main types of anchor are used to fix the floating platform to the seabed, each with unique characteristics. </p>
<ul>
<li><p>Drag anchors are similar to traditional boat anchors, but can have a 6 metre wingspan and <a href="https://delmarvryhof.com/products/anchors/stevpris-mk6/">weigh up to 50 tonnes</a>. They are dragged into the seabed by an installation vessel and embed themselves into the ground until the required holding resistance is achieved.</p></li>
<li><p>Pile anchors are like very large (up to 60 metres in length) but hollow nails. These anchors are hammered into the ground using an extremely heavy hammer. If the turbine is being installed above very hard soils or a rocky seabed, then a hole can be drilled to facilitate the pile installation.</p></li>
<li><p>Suction pile anchors are also hollow cylindrical tubes, but a sealed top cap creates suction pressure when water is pumped from inside of the pile. This forces the pile into the seabed without the need for hammering (an effect similar to the use of a plunger to unclog a drain). This is the type of anchor used to secure <a href="https://www.equinor.com/content/dam/statoil/documents/newsroom-additional-documents/news-attachments/brochure-hywind-a4.pdf">Hywind Scotland</a>.</p></li>
</ul>
<figure class="align-center ">
<img alt="The mooring line for a floating wind turbine at a dock." src="https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527488/original/file-20230522-21-jkclqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The mooring line for a floating wind turbine at Polarbase, Hammerfest, Norway.</span>
<span class="attribution"><a class="source" href="https://equinor.fotoware.cloud/fotoweb/archives/5020-Press/Folder%201/CorpPress/740aca6a921d4ec99a766665b0e01c0b.jpg.info">Øyvind Gravås and Even Kleppa/Equinor</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Choosing the right anchor</h2>
<p>Floating wind farms are being planned for areas such as the <a href="https://committees.parliament.uk/committee/162/welsh-affairs-committee/news/186547/floating-offshore-wind-in-celtic-sea-could-be-biggest-investment-opportunity-in-wales-but-certainty-over-projects-needed-from-uk-government/">Celtic Sea</a> and coastal waters <a href="https://windeurope.org/newsroom/news/france-launches-two-new-offshore-wind-tenders-more-needed/">west of France</a>. However, the presence of hard rock seabeds in both areas means drag anchors will be difficult to use. </p>
<p>Even in dense sand, a <a href="https://delmarsystems.com/video-vryhof-successfully-installs-stevsharkrex-in-australian-calcarenite-rock/">drag anchor</a> may only partly enter the seabed, creating inadequate support for the largest turbines. Drilled piles are the best way to anchor floating turbines to hard rock, so in this case, a driven pile might be the only option.</p>
<p>But driving these piles into the ground generates significant underwater noise that can be harmful for marine species. Research has also found that the movement behaviour of Atlantic cod <a href="https://www.sciencedirect.com/science/article/pii/S0269749122001270">subtly changed</a> in response to pile driving in the North Sea. </p>
<p>Even small changes in movement behaviour could affect individual growth and reproduction rates, potentially influencing the growth rate of entire populations.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0022460X16001681">Several techniques</a> have now been devised to reduce noise. This includes air bubble curtains to limit the ecological impact of floating wind farms. But these techniques may result in additional costs that could make pile anchors too expensive.</p>
<figure class="align-center ">
<img alt="Anchor pile hanging in crane of offshore installation vessel" src="https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527539/original/file-20230522-23-hefy0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The installation of pile anchors generates significant underwater noise.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/anchor-pile-hanging-crane-offshore-installation-411348676">ATJA/Shutterstock</a></span>
</figcaption>
</figure>
<p>The world needs a lot more wind turbines, and technology now allows installation further out to sea. But, as identified in our <a href="https://doi.org/10.1016/j.oceaneng.2023.114327">recent review paper</a>, these environmental and technical challenges for anchoring the structures in place must be addressed. </p>
<p>Without more investment in anchor technology to streamline installation, improve anchor performance and limit damage to the natural world, the potential of floating wind to help the energy transition will be greatly reduced.</p><img src="https://counter.theconversation.com/content/205319/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Benjamin Cerfontaine received funding from the European Union (Grant agreement ID: 753156) and the Supergen ORE Hub (SEAMLESS project). </span></em></p><p class="fine-print"><em><span>Susan Gourvenec receives funding from the Royal Academy of Engineering under the Chairs in Emerging Technologies Scheme </span></em></p>Offshore wind turbines are getting bigger and bigger – and many of them now float – here’s how we stop them drifting away.Benjamin Cerfontaine, Lecturer in Geotechnical Engineering, University of SouthamptonSusan Gourvenec, Royal Academy of Engineering Chair in Emerging Technologies - Intelligent & Resilient Ocean Engineering, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1594612021-04-23T00:48:04Z2021-04-23T00:48:04ZSatellites reveal ocean currents are getting stronger, with potentially significant implications for climate change<figure><img src="https://images.theconversation.com/files/396667/original/file-20210422-23-jud12b.jpg?ixlib=rb-1.1.0&rect=56%2C25%2C3358%2C1121&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/3913">NASA/Goddard Space Flight Center Scientific Visualization Studio</a></span></figcaption></figure><p>Scientists already know the oceans are rapidly warming and sea levels are rising. But that’s not all. Now, thanks to satellite observations, we have three decades’ worth of data on how the speeds of ocean surface currents are also changing over time.</p>
<p>In <a href="https://doi.org/10.1038/s41558-021-01006-9">research published today</a> in the journal Nature Climate Change we detail our findings on how ocean currents have become more energetic over large parts of the ocean.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/D9-HvHqO8-E?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Ocean currents in the North Atlantic. The Gulf Stream carries warm water across the Atlantic Ocean, from the Gulf of Mexico to Europe. All over the ocean we distinctly see circular flow features we call “ocean eddies”. (NASA/Goddard Space Flight Center Scientific Visualisation Studio)</span></figcaption>
</figure>
<h2>What are ocean eddies?</h2>
<p>If you looked down at the ocean from a bird’s eye view, you would see some mesmerising circular motions in the water. These features are called “ocean eddies”. They give the ocean an artistic flavour, reminiscent of Van Gogh’s Starry Night.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396430/original/file-20210422-15-l8hgvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Van Gogh’s Starry Night (1889) shares resemblance with the features we see in ocean circulation, in particular ocean eddies.</span>
</figcaption>
</figure>
<p>Eddies span somewhere between 10 and 100 kilometres across. They’re found all over the oceans. Certain regions, however, are particularly rich in eddies. </p>
<p>These include the Gulf Stream in the North Atlantic, the Kuroshio Current in the North Pacific, the Southern Ocean which surrounds Antarctica and, closer to Australia, the East Australian Current — made famous by the film Finding Nemo. </p>
<p>Ocean eddies are an integral part of ocean circulation. They move warm and cold waters from one location to others. They mix heat, carbon, salt and nutrients, and affect ocean conditions both regionally and globally.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/an-ocean-like-no-other-the-southern-oceans-ecological-richness-and-significance-for-global-climate-151084">An ocean like no other: the Southern Ocean's ecological richness and significance for global climate</a>
</strong>
</em>
</p>
<hr>
<h2>Satellites constantly watch the ocean</h2>
<p>One way we monitor movement on the ocean’s surface is by using specialised, powerful satellites orbiting Earth. Although these satellites are thousands of kilometres above us, they can detect even just a few centimetres of change in the sea’s surface elevation.</p>
<p>Then, through data analysis, we can take the change in sea surface elevation and translate it into ocean flow speeds. This can then tell us how “energetic” an ocean eddy is.</p>
<p>By carefully analysing satellite observations, our team discovered clear changes in the distribution and strength of ocean eddies. And these changes have never been detected before.</p>
<h2>How eddies have been changing</h2>
<p>Using available data from 1993 until 2020, we analysed changes in the strength of eddies across the globe. We found regions already rich in eddies are getting even richer! And on average, eddies are becoming up to 5% more energetic each decade.</p>
<p>One of the regions we found with the biggest change is the Southern Ocean, where a massive 5% increase per decade was detected in eddy activity. The Southern Ocean is known to be a hotspot for ocean heat uptake and carbon storage.</p>
<p>Until recently, scientists could only observe changes in ocean eddies by using either sparse ocean measurements or the limited satellite record. The satellite record has only just become long enough for experts to draw robust conclusions about the likely longer-term trends of eddy behaviour.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8zJ6tjJoUKo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Josué Martínez-Moreno gives a three-minute summary of our recent findings.</span></figcaption>
</figure>
<h2>Why is this important?</h2>
<p>Ocean eddies play a profound role in the climate by regulating the mixing and transport of heat, carbon, biota and nutrients in the oceans. Thus, our research may have far-reaching implications for future climate. </p>
<p>Scientists have known for decades that eddies in the Southern Ocean affect the overturning circulation of the ocean. As such, changes of the magnitude observed for eddies could impact the rate at which the ocean draws down heat and carbon.</p>
<p>But eddies are often not taken into account in climate predictions of a warming world. Since they are relatively small, they remain practically “invisible” in current models used to project future climate.</p>
<p>The impact of eddies is therefore either not resolved in climate projections, or is severely underestimated. This is particularly concerning in light of our discovery eddies are becoming more energetic.</p>
<p>Our research emphasises how crucial it is to incorporate ocean eddies into future climate projections. If we don’t, we could be overlooking a critical detail.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-an-alien-seaweed-invasion-spawned-an-antarctic-mystery-99944">How an alien seaweed invasion spawned an Antarctic mystery</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/159461/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Navid Constantinou receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Adele Morrison receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Andrew Kiss receives funding from the Australian Research Council and the Australian Government's Australian Antarctic Science Grant Program.</span></em></p><p class="fine-print"><em><span>Andy Hogg receives funding from the Australian Research Council and the Australian Government's Antarctic Science Grant Program. </span></em></p><p class="fine-print"><em><span>Josué Martínez Moreno receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Matthew England receives funding from the Australian Research Council.</span></em></p>Our team discovered clear changes in the distribution and strength of ocean eddies. These changes have never been detected before.Navid Constantinou, Research Fellow, Australian National UniversityAdele Morrison, Research Fellow, Australian National UniversityAndrew Kiss, Research Fellow, Australian National UniversityAndy Hogg, Professor, Australian National UniversityJosué Martínez Moreno, P.h.D. candidate, Australian National UniversityMatthew England, Australian Research Council Laureate Fellow; Deputy Director of the Climate Change Research Centre (CCRC); Chief Investigator in the ARC Centre of Excellence in Climate System Science, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1053712018-12-11T23:30:28Z2018-12-11T23:30:28ZCurious Kids: How does the Moon, being so far away, affect the tides on Earth?<figure><img src="https://images.theconversation.com/files/244951/original/file-20181111-116841-10bxw8f.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4224%2C3168&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When the sea level rises to its highest point, we call that high tide. When it falls to its lowest point, that's called low tide.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/bpinzini/4811517787/in/photolist-8kbhBe-t6Wqu-V9E4Rj-bwPoqJ-oY6DQ2-poSVN-8HEPDt-8zzY37-dgfS7Y-5ZWhDN-ooeRhw-oFjni7-drDheu-pgUnWK-7Efezw-WjLGdD-hGrGu4-2cMqEer-cLPprS-275aF2W-4LApJD-o9n4S1-P5NfW-Y9UcXm-oBbG-5a5jJr-VJTPAi-4RMFK7-8zwUKg-nFiY7-o9Fk99-39kKrk-dDYxAm-9pjmWu-qeQwN6-6p9dyV-dNkyY6-23gFUAK-kEBNt4-dNbvbU-NgC4KX-rg8Pyu-4T846v-5jZTGg-fEBa7u-nXAhnv-4r9o1w-7PHt5p-hfyc7-8zwNNn">Flickr/bpinzini</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. You can send your question to curiouskids@theconversation.edu.au. You might also like the podcast <a href="http://www.abc.net.au/kidslisten/imagine-this/">Imagine This</a>, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.</em> </p>
<hr>
<blockquote>
<p><strong>How does the Moon, being so far away, affect the tides on Earth? – Lachie, age 8, Doreen, Melbourne.</strong></p>
</blockquote>
<hr>
<p>Great question Lachie!</p>
<p>The short answer is that the Moon’s gravity pulls the oceans (and us) towards it. Even though the Moon is so far away, it is large enough that its force of gravity is strong enough to do that.</p>
<p>But before we get into how the Moon affects tides, let’s look at what tides are.</p>
<p>Tides are the rise and fall of water level in the oceans (and lakes, and even in your cup of water, but they’re very small). </p>
<p>When the sea level rises to its highest point, we call that high tide. When it falls to its lowest point, that’s called low tide.</p>
<p>The rise and fall of the tides is known as the tide cycle. If there’s one high tide and one low tide a day, like you would see if you went on holiday to Perth, it’s called a diurnal tide cycle. If there are two high tides and two low tides, like you see in Victoria, it’s called a semi-diurnal tide cycle. </p>
<p>The Moon has the most effect on the tides, but it’s not the only factor that affects them. The Sun and the Earth can also affect the tides. We’ll start with the Moon. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-are-there-living-things-on-different-galaxies-98562">Curious Kids: Are there living things on different galaxies?</a>
</strong>
</em>
</p>
<hr>
<h2>Tides and the Moon</h2>
<p>The Moon affects the tides because of gravity. You will have noticed that every time you jump, you always land back on the ground. This is because the Earth’s gravity is pulling you back down. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/244956/original/file-20181111-116841-1euc09g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Earth’s spinning means that another high tide occurs on the opposite side of the Earth to the Moon.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The Moon has gravity of its own, which pulls the oceans (and us) towards it. The Moon’s gravitational pull on us is much weaker than Earth’s, so we don’t really notice it, but we can see the Moon’s effect on the liquid water of the oceans. The oceans are pulled towards the Moon’s gravity slightly, causing a bulge or high tide on the side of the Earth closest to the Moon. </p>
<h2>The Earth’s effect</h2>
<p>If the Moon causes a high tide on one side of the Earth, what causes the high tide on the other side?</p>
<p>The Earth is spinning, which is why we have night and day. The Earth’s spinning means that another high tide occurs on the opposite side of the Earth to the Moon. </p>
<p>These two high tides draw water away from the rest of the oceans, causing two low tides between the high tides. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4UZxzyOVJ8Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Why do we have tides? - Forces of Nature with Brian Cox: Episode 2 - BBC One.</span></figcaption>
</figure>
<h2>The Sun</h2>
<p>The Sun, just like the Moon and the Earth, also has its own gravity which can affect the tides. Although the Sun is much larger than the Moon and has more gravity, it’s also much further away, meaning its pull on the tides is less than half as strong as the Moon’s. </p>
<p>It still does have an effect, though. When the Sun and Moon are in line with the Earth (when a full moon or new moon occur), their combined gravity cause very high tides (and very low tides), known as “spring tides.”</p>
<p>When the Sun and Moon are at right angles to each other (during a waxing or waning moon), the Sun helps to cancel out the pull of gravity from the Moon, causing lower high tides and higher than average low tides, known as “neap tides”. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/244955/original/file-20181111-37973-1i6ogp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lunar and Solar tides diagram.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>So the Moon affects the tides because of gravity, but gravity from the Sun and the spinning of the Earth also change how the tides behave.</p>
<p>Best wishes,</p>
<p>Mark Hemer.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-is-there-anything-hotter-than-the-sun-105748">Curious Kids: Is there anything hotter than the Sun?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/105371/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Hemer receives funding from the National Environmental Science Program Earth Systems and Climate Change Hub, and the Australian Renewable Energy Agency.</span></em></p>The Moon has gravity of its own, which pulls the oceans (and us) towards it.Mark Hemer, Senior Research Scientist, Oceans and Atmosphere, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/660482016-10-17T19:21:10Z2016-10-17T19:21:10ZCatching the waves: it’s time for Australia to embrace ocean renewable energy<figure><img src="https://images.theconversation.com/files/141932/original/image-20161017-14847-1a7gm58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Australia has some of the world's best ocean energy resources. </span> <span class="attribution"><span class="source">Wave image from www.shutterstock.com</span></span></figcaption></figure><p>Wind and solar may be currently leading the way in Australia’s renewable energy race, but there’s another contender lurking in the nation’s oceans. </p>
<p>Australia arguably possesses the <a href="http://www.sciencedirect.com/science/article/pii/S0960148116307406">world’s largest wave energy resource</a>, around 1,800 terawatt hours. Most of this is concentrated in the southern half of the continent, between Geraldton and Brisbane. To put this in context, <a href="http://www.industry.gov.au/Office-of-the-Chief-Economist/Publications/Documents/energy-in-aust/Energy-in-Australia-2015.pdf">Australia used 248 terawatt hours of electricity in 2013-14.</a> </p>
<p>Waves aren’t the only renewable power source in our oceans. The daily movements of the tides shift vast amounts of water around the Australian coast, and technology for conversion of tidal energy to electricity is more mature than any wave converters. </p>
<p>Ocean renewable energy also spans ocean thermal energy conversion, and energy captured from our large ocean currents (such as the East Australian Current). These represent less mature technologies with less opportunity in Australia. </p>
<p>Australia has <a href="http://www.ga.gov.au/scientific-topics/energy/resources/australian-energy-resource-assessment">abundant energy resources</a> – both renewables and fossil fuels. So what will it take to get ocean energy out of the water, and into our homes? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1651&fit=crop&dpr=1 754w, https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1651&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/141733/original/image-20161014-3982-14k2fjj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1651&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<h2>The task at hand</h2>
<p>The Paris Agreement, to which Australia is a signatory, aims to limit global warming to well-below 2°C. This will require <a href="http://www.climatechangeauthority.gov.au/sites/prod.climatechangeauthority.gov.au/files/files/CCA-RET-Review-published-updated.pdf">almost complete decarbonisation of global electricity systems by 2050</a>. </p>
<p>Of the 248 terawatt hours of electricity used in Australia, around 17 terawatt hours of this came from <a href="http://www.industry.gov.au/Office-of-the-Chief-Economist/Publications/Documents/energy-in-aust/Energy-in-Australia-2015.pdf">large scale renewable energy technology</a>, equivalent to about half of Australia’s <a href="https://www.environment.gov.au/climate-change/renewable-energy-target-scheme">Renewable Energy Target of 33 terawatt hours by 2020</a>. </p>
<p>To keep us on track to meet our international commitments, members of Australia’s Climate Change Authority recently proposed a <a href="https://www.climatecouncil.org.au/cca-minority-report">target of 65% by 2030</a>. This would require a rapid, large scale transition to alternative emission-free energy systems. </p>
<p>Wind and solar are currently leading the way, but we’ll need other technologies. This is not only to boost low emissions energy supply, but also to overcome the problem of intermittency due to the natural variability of the energy sources (when the sun doesn’t shine, or when the wind doesn’t blow). </p>
<h2>Out to sea</h2>
<p>Ocean renewable energy technologies (including wave and tidal) are emerging as a future contributor to Australia’s energy mix, and have a number of advantages over other sources.</p>
<p>Both wave and tidal energy devices are deployed offshore (not taking up limited land space) and are typically out of sight (deployed under the surface, or sufficiently offshore and low profile to not be obvious to the casual observer). </p>
<p>Although ocean energy resources also vary day-to-day like wind and solar, <a href="https://publications.csiro.au/rpr/pub?pid=csiro:EP113441">wave power has only a third of the variability of wind power</a>. It can also be forecast three-times further ahead than wind. Tidal energy is predictable over very long time-frames. </p>
<p>These attributes provide an advantage in a portfolio of clean energy technologies and have led to notable government and other investments in ocean renewable energy technologies in Australia. </p>
<h2>Ocean energy in Australia</h2>
<p>The Australian Renewable Energy Agency (ARENA) has contributed more than <a href="http://arena.gov.au/projects/ocean-energy">A$44.3 million</a> to at least nine ocean renewable energy projects to date (two closed before completion owing to technical and financial challenges). With other funds, more than A$122 million has been invested in ocean energy in Australia. </p>
<p>These funds have supported demonstration projects, including notable international successes (<a href="http://carnegiewave.com/projects/perth-project-2/">Carnegie Wave Energy Ltd</a>, and <a href="http://www.biopowersystems.com/port-fairy.html">BioPower Systems</a>), and other research. Several other demonstration projects have also been undertaken in recent years by start-up companies with self-funded support, and unique technologies. </p>
<p>The expected installed capacity from approved ocean projects in Australia is around 3.5 megawatts. So far total global installed capacity of wave energy projects is less than 5 megawatts. The EU has also been a major investor in wave energy projects, with approximately €185 million (around A$275 million) invested to date, for a total expected installed capacity of <a href="http://www.sciencedirect.com/science/article/pii/S2214166915000181">26 megawatts by 2018</a>.</p>
<p>Although tidal energy converters are the most ready of ocean renewables, a high-quality assessment of Australia’s national tidal energy resource is yet to be done. </p>
<p>Nevertheless several prospective sites in northern Australia and near Tasmania are attracting national and international attention for potential development owing to their attractive resource. Significant projects are in development, particularly in Europe, where tidal installed capacity is set to increase to <a href="http://www.sciencedirect.com/science/article/pii/S2214166915000181">about 57 megawatts by 2018</a>.</p>
<h2>Falling costs</h2>
<p>At the moment, the lifetime costs of ocean energy technologies are high. Until there are more than 10 megawatts of wave energy installed globally, costs will remain around <a href="http://www.irena.org/documentdownloads/publications/wave-energy_v4_web.pdf">A$500-900 per megawatt hour</a>. </p>
<p>By comparison, in 1981, when there were less than 10 megawatts of installed wind energy capacity, wind turbines cost around <a href="http://www.nature.com/articles/nenergy2016135">A$720 per megawatt hour</a>. In 1990 there were 2 gigawatts, and costs fell to around A$190 per megawatt hour. Now there are around 500 gigawatts of installed wind energy, and the cost of onshore wind is around A$110 per megawatt hour, similar to coal. </p>
<p>This experience suggests that <a href="http://www.irena.org/documentdownloads/publications/wave-energy_v4_web.pdf">costs for wave energy will decrease to A$170-340 per megawatt hour when installed capacity reaches 2 gigawatts</a>. But costs should not be the only performance indicator for ocean renewables. </p>
<p>Options are being explored to combine and integrate design of other infrastructure (such as <a href="http://www.sciencedirect.com/science/article/pii/S0378383912001809">wave energy capture as a coastal protection mechanism</a>, <a href="https://maribe.eu/wave-aquaculture">powering offshore aquaculture</a>, or <a href="http://www.tidallagoonpower.com/projects/swansea-bay/opportunities-and-benefits/">recreational amenities</a>) which will reduce relative costs. </p>
<h2>Support for an emerging industry</h2>
<p>To put ocean energy generators in our seas, planners, operators and financiers will increasingly require more knowledge of how much energy is available and where. </p>
<p>These decision-makers also need to understand barriers or constraints to ocean energy (in particular areas such as access to transmission infrastructure, or other uses of the sea such as fishing, aquaculture, tourism, shipping, ports, marine-protected areas). </p>
<p>To help answer these questions, ARENA and CSIRO have developed <a href="http://awavea.csiro.au/initial.htm">the Australian Wave Energy Atlas</a>. The atlas provides wave energy resource information together with details of available electricity infrastructure and spatial constraints for deployment. This allows users to identify the most viable sites for future wave energy projects, and ultimately ease the process of attracting capital and negotiating the consenting process. </p>
<p>While ocean renewable energy has many attractive features, there are still many challenges. The advantages of consistency and predictability of ocean energy become diminished if costs don’t fall below those of wind or solar supplemented with storage, which will offer the same advantages.</p>
<p>Other challenges include the technological advances needed to make generation devices ready and reduce costs; policy and regulatory barriers to project development; lack of awareness of ocean renewables and the potential they provide; limited body of knowledge on the environmental effects of large scale deployments; and the finance mechanisms to support the growing industry. </p>
<p>To overcome these challenges we’ll need to bring decision-makers, researchers, manufacturers, and businesses together to unlock the potential of our oceans. </p>
<p><em>The <a href="https://events.csiro.au/Events/2015/December/18/Australian-Ocean-Renewable-Energy-Symposium">Australian Ocean Renewable Energy Symposium</a>, running from today until October 20.</em></p><img src="https://counter.theconversation.com/content/66048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Hemer receives funding from the Commonwealth of Australia Australian Renewable Energy Agency, via the Australian Wave Energy Project, and the Department of the Energy and Environment National Environmental Science Program.</span></em></p><p class="fine-print"><em><span>Irene Penesis works for the Australian Maritime College, specialist institute of the University of Tasmania. She receives funding from the Australian Renewable Energy Agency via the 'Australian Wave Energy' project and 'Australian capability in arrays of ocean wave-power machines' project. Irene has also received grant funding from the Australian Research Council Linkage Program..In addition, performs research consulting with Australian wave energy and tidal energy device developers via AMC Search Ltd.</span></em></p><p class="fine-print"><em><span>Kathleen McInnes receives funding from the Commonwealth of Australia Australian Renewable Energy Agency, via the Australian Wave Energy Project, and the Department of the Energy and Environment National Environmental Science Program.
</span></em></p><p class="fine-print"><em><span>Richard Manasseh works for Swinburne University of Technology which leads a project funded by the Commonwealth of Australia's Australian Renewable Energy Agency, 'Towards an Australian capability in arrays of ocean wave-power machines'.</span></em></p><p class="fine-print"><em><span>Tracey Pitman receives funding from the Commonwealth of Australia Australian Renewable Energy Agency, via the Australian Wave Energy Project.</span></em></p>Australia has the world’s largest wave energy resource – so how do we unlock our ocean’s potential?Mark Hemer, Senior Research Scientist, Oceans and Atmosphere, CSIROIrene Penesis, Associate professor, Mathematics, University of TasmaniaKathleen McInnes, Senior research scientist, CSIRORichard Manasseh, Associate professor, Centre for Ocean Engineering, Swinburne University of TechnologyTracey Pitman, Project Manager, Oceans and Atmosphere, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/611762016-06-22T14:24:55Z2016-06-22T14:24:55ZIllegal fishing is a major threat to Africa’s blue economy<figure><img src="https://images.theconversation.com/files/126969/original/image-20160616-15117-1ud517u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A man carries marlins to the market in Mogadishu, the capital of Somalia. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/au_unistphotostream/8571826320/in/photolist-e4sRjY-crYC8o-9rPydx-q8Ffvb-cXs1hA-tZ2Xk-ap1ZKS-9bKoag-e9rLfT-5Qy2va-cXs9Nh-dKKKQb-cXrX9m-bo3JAU-hXV447-cXs43w-cNFsy3-a4Uk1Q-4SHbcE-pY4Sku-pHNoic-7xDntq-6qa5o7-pHQkGj-8JNbHx-8JNhLc-pHM2mA-5SzCfD-gzyCj-7etXFh-pH5Yec-5NYqjh-nPcZ9X-9cdfRA-pZZKAZ-p3HkLt-cFxUv7-pH2kt6-7yQ5sS-F9R8xx-71Xuwu-cXrcsy-a4Ru2Z-5Qa5g8-7yLikx-cXrLMb-3mkeoH-8P3MDh-cXshU9-5QC7Rf">AMISOM Public Information</a></span></figcaption></figure><p>The blue economy lies <a href="http://www.uneca.org/sites/default/files/PublicationFiles/blueeco-policy-handbook_en.pdf">at the heart of globalisation</a>. Ninety percent of international trade takes place via the sea and 95% of global communication relies on underwater networks. The blue economy encompasses all economic activity in and around rivers, lakes, streams, riverbanks, shorelines, groundwater, freshwater, seas and oceans.</p>
<p>The blue economy is mostly unknown, overlooked and underdeveloped in Africa. It could represent a major growth driver. </p>
<p>Its potential is not lost on the African Union (AU), which has made the blue economy one of the <a href="http://agenda2063.au.int/en/">priority areas</a> for the next 10 years: the blue economy holds immense potential as a key to a prosperous Africa. The United Nations Economic Commission for Africa (UNECA) and Seychelles Vice President Danny Faure share this outlook, seeing the blue economy as a potential source of <a href="http://www.uneca.org/stories/blue-economy-africa%E2%80%99s-future">blue gold</a>.</p>
<p>But where does it currently stand in Africa? Does it benefit African economies?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126162/original/image-20160610-29222-rcy5n7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fishing boats returning to shore in Nouakchott, Mauritania.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/m1key-me/14675718065/in/photolist-upnU2Y-ohSLQo-8dv2VY-7ahGu7-5NXA5E-aeouQa-omQTFP-isg4ih-qB4Ehd-nUJcU5-6NoGqD-pfM3vV-hTCevV-pY54uU-p4o5nq-EKJTh-skfCgq-e6bFFb-de3J4r-DTjeV-pbk2s8-auPYRt-6Uawmm-4vku23-oxyR9A-gkB1PX-9znhab-9qmks8-8wLFxa-isNnX8-cNFsy3-a4Uk1Q-4SHbcE-7Spvmi-8QvZV4-8dhFqD-pY4Sku-cXrVfG-pHNoic-cACZej-qhSHkx-7xDntq-6WocG8-b8qzTi-6qa5o7-e4sRjY-crYC8o-9rPydx-pHQkGj-q8Ffvb/">Michał Huniewicz/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Strategic significance</h2>
<p>The strategic significance of the blue economy for Africa is clear. UNECA has gone so far as to publish a <a href="http://www.uneca.org/publications/africas-blue-economy-policy-handbook">policy handbook</a> on the topic, echoing the African Union’s position.</p>
<p>According to the handbook, 38 of Africa’s 54 countries are coastal states and more than 90% of import-export occurs via the sea. The territorial waters controlled by African nations stretch out over 13 million km², with a continental shelf of about 6.5 million km², including exclusive economic zones. For the AU, the blue economy represents a new frontier of African renaissance.</p>
<p>There are tensions between African nations over the <a href="http://www.peaceau.org/uploads/au-2-en-2013-delim-a-demar-user-guide.pdf">demarcation of maritime borders</a>. But the fishing industry employs nearly 12.3 million Africans. And the blue economy could potentially solve nutritional and food security problems for nearly 200 million Africans. It has the potential to provide vital nutrition through underused resources in fresh and salt water fish. </p>
<p>A grassroots, holistic and collaborative approach would make it possible to establish a blue development strategy, taking into account climate change and sustainable development. But several outside forces jeopardise its success.</p>
<h2>The danger of illegal fishing</h2>
<p>Blue economic activities are hampered by natural phenomena like storms and rising sea levels. But they are also impeded by human activities such as piracy, and the arms and slave trades. Illegal fishing is one of the most significant threats.</p>
<p>Based on Africa’s financial inflows and outflows, <a href="http://www.uneca.org/publications/africas-blue-economy-policy-handbook">UNECA reckons</a> that the continent loses US$42 billion per year through illegal fishing and logging activities.</p>
<p>The <a href="http://www.uneca.org/sites/default/files/PublicationFiles/blueeco-policy-handbook_en.pdf">plundering of Africa’s blue economy</a>, perpetrated by European, Asian and Russian ships, is a reality. In <a href="http://www.un.org/africarenewal/magazine/july-2009/safeguarding-africa%E2%80%99s-fishing-waters">West Africa</a>, the economic loss is estimated at about $700 million per year.</p>
<p>Illegal fishing – untaxed and unregulated – impoverishes nations and triggers cross-border population displacement. According to <a href="http://www.thinkingafrica.org/V2/portfolio/economie-bleue-et-pillage-des-ressources-halieutiques-en-afrique-kombe/">Professor Jean-François Akandji-Kombé</a> at the University of Paris, the current situation can be explained by the fact that:</p>
<blockquote>
<p>The sea as economic entity is a new concept in Africa. For a long time, the continent didn’t have the means to exploit marine resources, or the means to assert political power over the seas. There were no seafaring people or nations to speak of in Africa. These people, these nations focused on the land, not the sea.</p>
</blockquote>
<p>The European Union has woken up to the magnitude of the systematic plunder of African fishing resources, and its potential political consequences. In recent years, it has been working to establish fishery <a href="http://ec.europa.eu/fisheries/cfp/international/agreements/index_en.htm">partnership agreements</a> with African countries like Cape Verde, the Comoros, Côte d’Ivoire, Gabon, Guinea-Bissau, Liberia, Madagascar, Mauritania, Morocco, Mozambique, São Tomé and Príncipe, Senegal and the Seychelles.</p>
<p>China’s policy has been remarkably shameless regarding illegal fishing. A number of African states hold Chinese vessels <a href="http://www.voanews.com/content/china-expands-global-fishing-fleet/2815656.html">responsible</a> for plundering African maritime resources and have called on the Chinese government to <a href="http://m.voanews.com/a/african-countries-call-for-china-to-stop-illegal-fishing/3133482.html">stop illegal fishing in West Africa</a>.</p>
<p>African governments must therefore come up with strategic frameworks if their people are to reap the benefits of this potential bounty.</p>
<p><em>Translated from the French by Alice Heathwood for <a href="http://www.fastforword.fr/">Fast for Word</a>.</em></p><img src="https://counter.theconversation.com/content/61176/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Abdou Hassan is a member of the Institute for Research and Teaching on Peace in Africa (Thinking Africa).</span></em></p>The blue economy is unknown, overlooked and underdeveloped in Africa. It could represent a major growth driver for the continent.Adam Abdou Hassan, Enseignant chercheur, Université de Rouen NormandieLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/546072016-04-01T04:24:00Z2016-04-01T04:24:00ZWhy managing ocean acidification is crucial for South Africa<figure><img src="https://images.theconversation.com/files/112896/original/image-20160225-15156-1mdszae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">South Africa's oceans offer numerous economic opportunities, if ocean acidification is dealt with properly.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The southern tip of Africa is washed by two oceans: the Indian and Atlantic oceans. This should allow South Africa to benefit economically from various activities through developing the ocean economy. Fisheries, tourism and maritime activities are some of the sectors that can underpin the economy. </p>
<p>There is enormous potential for countries with an ocean economy. There are a growing number of states in the Indian Ocean that are pursuing its potential benefits. Mauritius and the Seychelles are among the most prominent. </p>
<p>Mauritius’ initial focus is on the exploration of the seabed for hydrocarbons and minerals, as well as fishing, seafood processing, aquaculture and <a href="http://www.investmauritius.com/investment-opportunities/ocean-economy.aspx">marine renewable energies</a>. </p>
<p>The Seychelles is exploring the blue economy as a model for <a href="http://natureseychelles.org/what-we-do/blue-economy">sustainable development</a>. </p>
<p>For both these small island states, this new economy is showing promise. But it is at the very beginning of implementation. There is also the risk that not managing it carefully and sustainably could result in failure to improve the well-being of society and further degrade natural resources.</p>
<p>The South African government, through the Oceans Laboratory of <a href="http://www.operationphakisa.gov.za/operations/oel/pages/default.aspx">Operation Phakisa</a>, is trying to fast-track the implementation of solutions to critical development issues. This initiative focuses on unlocking the economic potential of South Africa’s oceans. Its focus areas include the strengthening of the marine transport and manufacturing sectors, aquaculture and marine tourism.</p>
<p>But one of the major challenges to its success is <a href="http://www.pmel.noaa.gov/co2/story/Ocean+Acidification">ocean acidification</a>. This is the reduction of pH levels in the ocean over an extended period of time. It is a growing environmental concern linked to <a href="http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F">climate change</a>. Ocean acidification is caused by the uptake of carbon dioxide from the atmosphere. </p>
<h2>Oceans under threat</h2>
<p>Ocean acidification is a global process with local impact. The potential effect has <a href="http://www.oceanacidification.org.uk/">been studied</a> across the world. More acidic seawater has a dramatic effect on species that deposit calcium as part of their life-cycle. Some of these include oysters, clams, sea urchins, shallow-water corals, deep-sea corals and calcareous plankton. </p>
<p>The entire food system may be at risk with shelled organisms at risk. More than <a href="https://www.msc.org/healthy-oceans/the-oceans-today/fish-as-food">a billion people</a> worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies around the world also depend on fish and shellfish.</p>
<p>Other problems resulting from ocean acidification include loss of biodiversity and major losses in fisheries and mariculture production (the farming of marine life for food). These threaten food security, coastal defences, tourism and recreational <a href="https://www.iaea.org/ocean-acidification/download/8%20June%202015/RAPPORT%20SCIENTIFIQUE.pdf">activities</a>. The impact is more prominent in developing countries due to their greater dependence on living marine resources from fisheries and mariculture. </p>
<p>Based on scientific data and projections of change, ocean acidification is a serious threat to South Africa’s plans to develop the ocean economy. This should be acknowledged and strategies should be designed to deal with it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112897/original/image-20160225-15182-102xxvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ocean acidification can have a major impact on marine life and biodiversity.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>There is a need for urgent action at all levels of government as well as at an <a href="https://www.iaea.org/ocean-acidification/download/8%20June%202015/RAPPORT%20SCIENTIFIQUE.pdf">international level</a>. The international community can encourage national and local governments to intensify efforts further to mitigate carbon dioxide emissions. This will reduce the impact of both climate change and ocean acidification.</p>
<h2>Helpful policies</h2>
<p>There are also several governance strategies that can be used to deal with ocean acidification.</p>
<p>It’s important to promote and strengthen policies and legislation for coastal and ocean management to prevent further degradation of ecosystems. There are governance mechanisms that allow for adaptive management of effects from ocean acidification in South Africa. But the recognition of the seriousness of ocean acidification remains limited.</p>
<p>One way to improve adaptation options and prevent further degradation is to restore and protect coastal and marine ecosystems. The recent publication of draft notices and regulations for 22 proposed <a href="https://www.environment.gov.za/mediarelease/molewa_22newproposed_mpas">Marine Protected Areas</a> under Operation Phakisa is a positive step towards promoting greater environmental resilience in South Africa.</p>
<p>The economic impact of ocean acidification on tourism may include loss of profits and employment. It can also lead to loss of tourist infrastructure due to decreased storm protection from reefs. This needs to be considered in planning activities that form part of the ocean economy. </p>
<p>Equally, South Africa’s ocean economy is emphasising the growth and development of the mariculture industry. Ocean acidification is certain to have an impact on small-scale fisheries and <a href="https://www.iaea.org/ocean-acidification/download/8%20June%202015/RAPPORT%20SCIENTIFIQUE.pdf">mariculture</a>.</p>
<p>Knowledge, expertise and capacity are also not globally distributed and it’s vital to promote and build local scientific capacity. Research and technology that requires international collaboration is also important.</p>
<p>A warning system is also crucial. It could forecast and warn communities of potential problems. For example, the <a href="http://www.goa-on.org/">Global Ocean Acidification Observing Network</a> is a collaborative international approach to document the status and progress of ocean acidification in open-ocean, coastal and estuarine environments.</p>
<p>There must be a concerted effort to explain ocean acidification and the threat it poses to the public. Special attention should be given to people with influence, national administrations and NGOs. In many developed countries, the importance of ocean acidification is increasingly being recognised and its mitigation <a href="http://ocean.si.edu/ocean-acidification">promoted</a>. The same is not yet true for developing nations.</p><img src="https://counter.theconversation.com/content/54607/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>I regularly receives funding for bona fide research projects from a variety of external sources, government and the CSIR. I have previously received CSIR funding to work specifically on ocean acidification. </span></em></p>South Africa has the opportunity to benefit from its ocean economy. But to do that, the country needs to put better policies in place to counter ocean acidification.Louis Celliers, Principal Scientist, Council for Scientific and Industrial ResearchLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/370872015-04-08T10:05:16Z2015-04-08T10:05:16ZWhy ocean energy needs a cyberinfrastructure to thrive<figure><img src="https://images.theconversation.com/files/77233/original/image-20150407-26515-3aaqlh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">wave via www.shutterstock.com</span></span></figcaption></figure><p>Almost <a href="http://energy.gov/eere/water/marine-and-hydrokinetic-resource-assessment-and-characterization">one third</a> of our electricity needs can be met by a predictable, renewable and yet largely untapped resource: ocean waves. </p>
<p>Generated by wind blowing over ocean waters, ocean waves travel large distances with little loss of energy. As such, they are a renewable resource that is more consistent and predictable than wind or solar generation. </p>
<p>Our research team at Lehigh University is examining how to design, operate and maintain future wave energy farms by using digital technologies to integrate them smoothly to the electric grid. </p>
<p>Wave farms contain arrays of wave energy converters (WECs), devices that convert the energy in rolling ocean waves to electricity. Smart wave farms also include energy storage such as batteries, sensors, communications capabilities, computational resources, and electronics to deliver electricity to an on-shore grid connection point. </p>
<p>All these components, as well as the algorithms that control them, together describe the cyber-physical infrastructure of the wave farm. Our team, which has people with a background in everything from wireless data communications to fluid dynamics, is determining how to optimally deploy and operate this infrastructure. </p>
<p>We are exploiting the predictability of ocean waves to aid people who operate wave farms and to optimize farm production. We are also deeply interested in the sustainability and market potential for future wave farms. Unlike other renewables that require fossil-fuel based generation to balance out their variations, consistent wave power will have lower CO2 emissions. We are evaluating this effect and are studying what profits wave power producers can expect in the electricity market.</p>
<h2>Predictable and renewable</h2>
<p>Estimates of economically recoverable wave energy along the US coasts range up to <a href="http://energy.gov/eere/water/marine-and-hydrokinetic-resource-assessment-and-characterization">1,170 terawatt-hours</a> (Twh) per year using existing technology. </p>
<p>Total electricity consumption in the US is approximately 4,000 TWh/year and coastal states use nearly 80% of the nation’s electricity. This means that the potential for clean, renewable wave power production in the US is very high.</p>
<p>Ocean wave characteristics can be reliably predicted up to 48 hours in advance and waves are available 90% of the day on average, compared to 20-30% for wind and solar. This key benefit will provide wave power producers more lucrative market opportunities than are currently available to more variable renewables. These profits could also offset the high initial costs of installing wave farms. </p>
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<img alt="" src="https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=782&fit=crop&dpr=1 600w, https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=782&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=782&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=982&fit=crop&dpr=1 754w, https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=982&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/77236/original/image-20150407-26512-hu0s30.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=982&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">PowerBuoy from Ocean Power Technologies captures energy from waves.</span>
<span class="attribution"><a class="source" href="http://en.wikipedia.org/wiki/Wave_power#/media/File:Optbuoy.jpg">Ocean Power Technologies</a></span>
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<p>As an emerging industry, wave energy conversion faces other challenges. For example, more testing infrastructure is needed. But to do that, current regulatory and permitting procedures have to be updated for this technology. And the environmental impact of withdrawing large amounts of wave energy must be studied further. </p>
<p>Over the past two decades, several types of WEC devices have been developed and deployed. There have been commercial-scale wave farms deployed in Australia and Europe, but none has been put online in the US. </p>
<p>For ocean energy to scale up, we will need to fill some gaps in our knowledge. In the future, wave farms will not be a collection of individual generators. Instead, they will be a complex cyber-physical system and require interdisciplinary tools. </p>
<h2>Complex interactions</h2>
<p>We are interested in the wave farm as a system, and in its interactions with the ocean environment, the power grid, and the electricity market. We are exploring the predictability of waves using both in-ocean sensors as well as forecasting algorithms. The predictions can be used to adapt the WECs energy capture, or energy storage decisions. </p>
<p>In our project, we are working on wave farm systems that blend tools from hydrodynamics as well as communications and computing. We will use sensors and controllers to predict power, optimize output and integrate with electricity markets. We will validate the economic and environmental feasibility of wave power and use our research and development to realize the potential of wave energy conversion at large scale.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/KjTPqpEB79o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>WECs in a farm will also interact with each other. Besides absorbing power from incoming waves, individual WECs reflect waves which will mix with incoming waves and impact how much energy can be captured at neighboring WECs, and vice versa. These interactions must be understood and accounted for in controlling the farm’s total output. This total power produced will in turn impact grid integration, emissions, and market interactions. </p>
<h2>How a wireless researcher began studying the ocean</h2>
<p>Our project team is comprised of researchers from a wide variety of backgrounds: fluid dynamics, signal processing, operations research, economics and wireless communications, which is my own background. So how does a wireless communication researcher end up working on wave energy farms? The answer is in the following picture:</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/73747/original/image-20150304-31863-91g0hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An artist’s rendition of a wave farm with several Ocean Power Technologies’ PowerBuoy wave energy converters. Image is used with permission from Ocean Power Technologies.</span>
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<p>The buoys are WECs collecting energy from undulating sea waves. To me, they resemble wireless antennas receiving sinusoidally varying electromagnetic signals. In both cases the buoys/antennas are placed in a field of waves to capture energy. The statistical variations of wireless radio signals and ocean waves are similarly captured. </p>
<p>Significant performance gains in modern wireless communication systems have come from using multiple antenna systems. For wave energy to be successful at the grid-scale, we will also require multiple buoys, or wave farms. </p>
<p>There are solid connections between a wave farm and a communication system scenario I have studied extensively in the past. Making these initial connections got my foot in the door and I have been making similar connections since.</p>
<h2>Desalination?</h2>
<p>Besides powering the electricity grid, wave farms could also be used in powering a variety of off-shore applications. Our project team is interested in developing wave farm designs tailored for such energy needs. For example, we are interested in developing smaller scale wave farms that address the energy requirements for off-shore water desalination processes. </p>
<p>In many parts of the world, groundwater is shrinking but sea water is prevalent. The presence of sea water may also imply availability of local wave energy resources that can feed water desalination systems. We are interested in developing cyber-physical infrastructure for such autonomous wave farms. The solutions may push forward water desalination technologies that could in turn help address the global water crisis.</p><img src="https://counter.theconversation.com/content/37087/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shalinee Kishore receives funding for research on ocean wave energy farms from National Science Foundation under grants 1442858 and 1400164.</span></em></p>Research project combines digital technologies with farms of wave generators to bring plentiful and reliable ocean power closer to commercialization.Shalinee Kishore, Associate Professor Electrical and Computer Engineering, Lehigh University Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/286702014-07-09T20:11:54Z2014-07-09T20:11:54ZRenewables still have a long way to go to compete with fossil fuels<figure><img src="https://images.theconversation.com/files/53378/original/8sns6q8z-1404880575.jpg?ixlib=rb-1.1.0&rect=45%2C36%2C5934%2C3935&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Wind farms: great, unless it's not windy.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File%3ALeonards_Hill_Hepburn_Wind_Farm.JPG">mattinbgn/Wikimedia Commons</a>, <a class="license" href="http://artlibre.org/licence/lal/en">FAL</a></span></figcaption></figure><p>Australia has some fairly ambitious goals for green energy: a <a href="https://theconversation.com/topics/renewable-energy-target">renewable energy target</a> (currently <a href="https://theconversation.com/renewables-inquiry-leader-vows-open-mind-on-targets-future-23305">under review</a>) of 20% of electricity from renewables by 2020, and a forecast to get <a href="http://www.bree.gov.au/sites/default/files/files//publications/aep/australian-energy-projections-to-2050.pdf">51% of electricity from renewables by 2050</a>. </p>
<p>But in setting these targets, not enough consideration is being given to the difficulty of getting the job done – in terms of generating enough renewable energy, and of storing it so it can be supplied 24 hours a day. </p>
<p>Renewable energy sources, mainly hydroelectric and wind with a smaller amount of solar, currently provide around 13% of Australia’s power; the rest comes from fossil fuels. Increasing renewable sources to and beyond 20% will depend on being able to generate power at the right locations, and building enough storage infrastructure too.</p>
<h2>The problem of consistency</h2>
<p><a href="https://theconversation.com/explainer-what-is-hydroelectricity-12931">Hydroelectric power</a> requires reliable rainfall upstream; <a href="https://theconversation.com/topics/wind-power">wind power</a> needs consistent wind speeds; and <a href="https://theconversation.com/topics/solar-power">solar energy</a> naturally depends on sunshine. <a href="https://theconversation.com/explainer-what-is-geothermal-energy-12913">Geothermal</a> and <a href="https://theconversation.com/explainer-what-is-ocean-energy-12921">ocean</a> power sources are unproven at any scale in Australia, while <a href="https://theconversation.com/topics/bioenergy">biomass</a> resources will always be very limited without having a <a href="https://theconversation.com/if-we-burn-wood-for-energy-we-cant-have-our-cake-and-eat-it-15634">major impact on food production</a>.</p>
<p>The common factor for all of these sources is irregular weather patterns, which lead to uncertain and intermittent power output. This is a big challenge for electricity generators and retailers, and it can cost lots of money. </p>
<p>Solar and wind, even in favourable locations, typically produce power at around 20-30% of their total theoretical capacity, compared with more than 90% for many fossil fuel plants. This means that to produce the same amount of electricity, the renewable plant must have around four times the capacity of the fossil fuel plant. For example, a 1000 megawatt wind farm would typically be needed to produce the same electricity output as a 250 megawatt coal or gas plant.</p>
<p>To look at it another way, while fossil fuel plants can be online 24 hours a day, we can only rely on wind or solar sources to generate electricity for an average of 5 to 8 hours each day (although the energy can potentially be stored for use later in the day, which we will come to shortly).</p>
<h2>Consumer expectations</h2>
<p>Australians expect that when they turn on a light switch, be it 8 am or 8 pm, the light will come on. If we depended solely on renewable energy for direct power generation, this wouldn’ happen. We need baseload electric power, generated reliably around the clock, to guarantee security of supply.</p>
<p>Advocates for high levels of renewable electricity, such as supporters of the <a href="http://www.bree.gov.au/">Bureau of Resources and Energy Economics</a> projection of 51% by 2050, or even for 100% renewable energy, argue that energy storage can overcome this problem. In reality, however, few financially and technically viable solutions exist to store large amounts of electrical energy for significant periods of time. <a href="https://theconversation.com/how-pushing-water-uphill-can-solve-our-renewable-energy-issues-28196">Pumped water storage</a> is the favoured solution, but this requires dams and water normally near to the power sources to minimise transmission losses. </p>
<p>Australia has very limited capacity for growth in this area. Battery storage is typically limited to tens of kilowatt hours discharged over a few hours or days at best. Batteries will not serve the needs of most industries. Molten salt storage has been advocated for solar thermal plants, but the scale required to achieve more than a few hours’ storage makes this solution unviable for most applications. An electrolysis process to produce hydrogen from water for subsequent use in a gas-fired plant or with fuel cells is possible, but unlikely on a large scale because of practicality and cost.</p>
<h2>Weighing the options</h2>
<p>So what options do we have in Australia to ensure security of electricity supply on a 24/7 basis? The reality is that the higher the proportion of electricity produced from renewable sources, the more we must have available standby baseload capacity from fossil- or nuclear-fuelled plants for when the wind does not blow and the sun does not shine. </p>
<p>Of course, it is expensive to have power stations sitting there on standby, which in turn drives up the cost to consumers. Gas-fired standby plants are favoured because of their flexibility, but the long-term security of supply and the <a href="https://theconversation.com/dont-get-burnt-by-gas-price-rises-tips-for-homes-and-industry-28198">escalating cost of gas</a> are significant concerns.</p>
<p>A credible Australian energy policy must reflect the limitations on the use of renewable energy sources, and focus more on other greenhouse gas mitigation strategies. It has been proven internationally that coal-fired electricity generating plants can be around twice as efficient as most existing Australian plants. Technology also exists to capture around 90% of all the emissions from fossil-fuelled plants, but further cost reductions and incentives will be needed to help generators invest this new equipment. The other option is to build low-emitting nuclear plants, but that is another story. And consumers can also focus on trying to reduce their own power use.</p>
<p>More attention must be given to greenhouse gas emissions from outside the energy sector, which account for more than 60% of all Australia’s emissions. Direct fuel combustion, transport and agriculture <a href="http://www.climatechange.gov.au/reducing-carbon/reducing-australias-emissions/australias-emissions-projections">contribute some 46% of emissions</a> – and might offer easier ways to cut down.</p><img src="https://counter.theconversation.com/content/28670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frank Larkins does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Australia has some fairly ambitious goals for green energy: a renewable energy target (currently under review) of 20% of electricity from renewables by 2020, and a forecast to get 51% of electricity from…Frank Larkins, Professor Emeritus and Former Deputy Vice Chancellor, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.