I don't believe they are, at least not on the scale required for the current population/demand.

From what I have seen online, the EROEI of all renewable energy sources is signficantly less than that of oil energy. I.E. They are signficantly less 'energy dense' and require an enormous amount of infrastructure compared to extraction and processing of oil energy.

A back of the envelope calculation will reveal that, to replace its current oil energy consumption with solar voltaic energy, the US would have to create an area the size of Malaysia packed solid with solar panels.

Consider the amount of industrial energy it would require to produce that quantity of solar panels, to deploy them, to maintain them and to replace each one at the end of its 20 year? life span.

I just don't see how this could be acheived without oil energy.

Consider biofuels. How long does it take to establish a crop of oil palms, extract the oil and process it? Several years at least? Over how many acres?

Compare that to a single oil rig of about an acre size pumping millions of litres of oil out of the ground daily.Vast qauntities of oil are available immediately compaired to many years to grow a biofuel crop to maturity, to harvest it from thousands of acres and extract the oil from it.

I just can't see it being remotely feasible on the same scale as oil energy.

Thanks Mr Boyles. Let me put it this way.

1. Install a swadge of solar thermal, PV and wind generating capacity.
2. Dedicate the power thus generated to extraction and refining of material used in fabrication of solar thermal, PV and wind generating equipment.
3. Fabricate solar thermal, PV and wind generating equipment from the materials produced in step 2.
4. Install the solar thermal, PV and wind generating equipment produced in step 3.
5. With this new generating capacity, increase the throughput of step 2.
6. With this new fabricating capacity, increase the throughput of step 3.
7. Go to step 4.

You see, this is an interminable loop that will go to infinity, sooner or later.
At some stage, it will be producing 18 terawatts more power than than its self-sustenance requires.

Mind you, by then we'll need less power because there'll be fewer people because of all the simultaneous poverty reduction and education and emancipation programmes.

On the other hand, I understand that the programme you suggest (reversion to pre-Modern agrarian technology) has been implemented in recent decades, achieving the very depopulation for which you argue, in Cambodia under the Khmer Rouge.

Assuming that obtaining "biofuels from residues" is not intended for use in female emancipation, I agree with Jerry.

However, without stabilising third world population in conjunction with transitioning to clean sustainable energy sources, we stand to lose.

One thing I'd like to see is the nuclear lobby along with the clean sustainable crowd campaigning for and aiding women in third world countries.

All good in theory. But what is the EROEI of waste biomass fuels. How much energy do you have to put into the process and how much net energy do you get out of it.

I think you will find that, on large scale, the EROEI of waste biomass fuels is very low or possibly negative.

EROEI = Energy Returned On Energy Invested

Jerry I see a lot of business and economic 'fluff' in your link.

But where is a comprehensive study on the EROEI of waste biomass fuels compared to current estimates of the EROEI of oil......which has been declining as the easy to access oil deposits have been declining.

Thanks for your thoughtful explanations Mr Boiles, particularly provision of a few references so that we know what on earth you are raving about.

"Energy returned on energy invested", eh? Regarding transport fuels, is that calorific value of the fuels consumed, or the kinetic energy thus gained? If it is the former, then you can knock EROEI down by a factor of 4 or 5 due to the inherent inefficiencies of automotive motors plus drivetrains.

And then, what if we all stopped driving Hummers, and start driving eSmarts at least for trips to the supermarket?

What if we stopped transporting coal and iron ore to China, but made the steel here and shipped that to China? That's one shipload of steel replacing two shiploads of iron ore and one of coal. What if we started recycling metals, retaining the value of the embodied energy? You may want to read Geoffrey Brooks's The Conversation piece "Treasure your metal: why we need to respect embedded energy" (http://theconversation.edu.au/treasure-your-metal-why-we-need-to-respect-embedded-energy-6802).

Finally, the embodied energy of rooftop solar panels may decrease the need for energy embodiment in high tension power lines all over the country (and put a fair nudge in transmission losses too).

So before a "top-down" perusal of the challenge causes us to despairingly return to a Kampuchean Stone Age, perhaps we can take a "bottom-up" approach and discover how much progress we can make.

Jeeeeze Authur....you have a pair of fingers don't you.

But since you find it to mentally taxing to google EROEI then here:

http://en.wikipedia.org/wiki/Energy_returned_on_energy_invested

There is currently no accepted accounting method to account for all the energy inputs of an economic process as opposed to a biological, chemical or physics process. Or any agreed place to draw the line between interconnected economic processes.

But as with tripple bottom line accounting, we need to develop an rigorous accounting process for determining EROEI of primary energy sources in our economy......and fast as you will soon understand from this next link.

http://energy.sigmaxi.org/wp-content/uploads/2009/05/eroi.jpg

Note the enormous difference between the EROEI of oil energy compared to biofuels and solar voltaics.

We need to establish quickly whether or not we are flogging a dead horse in attempting to convert our economy to these as primary energy sources in place of oil.

And if they are not simply economically unviable, then we need to establish what population level and level of economic activity these energy sources can sustain long term.

Because on face value they will not even come close to sustaining our current population and economic level.

Thanks Mr Boiles, I've already had a little look at the wikipedia entry to which you refer me.

I appreciate the particularly pugnacious tone with which you respond to any attempt to query your assertions; in accordance with how you like your communications, a glaringly obvious fault in your overly simplistic case is that you are disregarding opportunities for both methodological and technological advances to both improve the effectiveness of renewable energy technologies to meet demand, and for per capita demand to decrease.

While my optimism may seem Panglossian to you, I fully expect that despite our best efforts, human populations will undergo catastrophic decreases from time to time over the next couple of centuries, even without our resorting to the Pol Pot solutions you advocate.

Pugnacious indeed Authur?

Well you condascending attitude invites such a response!

And would you care provide evidence that I have, on one single occasion, advocated 'pol pot' solutions. I.E. Genocide, death camps, torture,.....

Mr Boyles, my initial remarks to you were not intended to be condescending in any way. Noting that you have persisted in addressing me only by mis-spelling my surname, perhaps I have mistaken your dyslexia for a deliberately insulting tone.

You then went on to tell me that I just don't get it, introducing a curious acronym (EROEI) without attempting a summary explanation. In my book, that amounts to arrogance.

You stated: "The switch to these renewable energy souces MUST be accompanied by measures to reduce the global population as quickly and humanely as possible."

I replied: "Regarding reducing the global population as quickly and humanely as possible, poverty reduction and female emancipation and education seem to work a treat while avoiding totalitarianism."

Reviewing our discussion, I see that I have chosen to identify advocacy of top-down, centralised population control, when coupled with return to agrarian technology, as leading to situation akin to Cambodia in the late 1970's.

That's what Pol Pot was trying to do. Torture and mass executions was simply the political first step.

OK Arthur may be I inadvertently did start it with my comment about not getting.

But that comment was an expression of exasperation rather than a deliberate insult.

The fact is that dont't get it by virtue of the fact that you had no idea what EROEI was and you were not commenting on alternative energy sources from a position of complete big picture knowledge of the issue.

And I believe at some point I put the following at the bottom of one of my posts to explain what EROEI was:

"Energy Returned On Energy Invested"

Now I conceed that there is currently no accepted and clearly defined means of doing the EROEI accounting but never the less this must be taken into consideration when assessing replacement primary energy sources for oil.

EROEI is a fundamental of biological and physical process. Any system or process with an EROEI less than 1 cannot be sustained without and external energy source.

And this is of critical importance with solar voltaics etc. If the rate of energy consumption in producing and maintaining solar voltaic power stations etc excced the rate at which these power stations can produce and store energy then such primary energy sources can never replace oil.

Even if solar voltaics etc have an EROEI above 1 but signficantly less than that of oil then we will have enormous difficulty in producing and maintaining them on the scale that is currently required by the global population without oil energy as well as solar votaics etc.

And as for you comparison of population control and reduction with pol pot.......utterly irrelevant abd rediculous.

Pol pot was about maintining political power and eliminating perceived political enemies and not about population control!

Impartial reduction of average fertility has nothing what so ever to do with death camps as employed by pol pot et el to eliminate political enemies. I fail to see how preventing unnecessary and unwanted pregnancies acheives the goal of eliminating political enemies.

Biofuels for residues and waste streams is very much a work in progress, so that 2012 is far to soon to be doom-mongering.

I suggest you peruse Reuters' science news website, Science Daily (www.sciencedaily.com) to stay up to date on developments in alternative fuel development. The alternative fuels section (www.sciencedaily.com/news/matter_energy/alternative_fuels/) also has links to collections of reports in related fields, including references and links to the research reports.

That may help.

If you have been reading this David and you still didn't know what EROEI was then that would suggest that either the scientists involved are not considering the larger picture or at least they are not detailing EROEI explicitly so that non-scientists can see the limitations of biofuels.

http://www.energybulletin.net/stories/2006-04-12/getting-decent-return-your-energy-investment

QUOTE

Also consider biodiesel and ethanol; their energy profit ratios are very low. In spite of this you will hear everyone from the president of the United States to the governor of Washington State touting them as the fuels of the future. It will not be possible to run society as we know it today, which is driven by the very high energy profit ratio of petroleum, on the low EROEI offered by biodiesel and ethanol. Not that these fuels might not be useful, but they will be useful only to a society that has adapted to living on a lower energy budget. If you understand EROEI, you know more about energy than either President Bush or Governor Gregoire. Perhaps you will be able to teach them a few things.

END QUOTE

Biofuels are not a means of avoiding addressing human society's fundamental problem - to many people consuming too much!

Just been wondering if there is any chance while you good gentlemen have been discussing who know what, have you bothered to have a look at the reference I posted at the end of this thread?

Tremendous Australian research.

I have read some material in the link provided by Jerry Vanclay and I have read breifly through your link Roger.

My problem with them is this.......

They are focused on commercial viability of waste biomass biofuels but that 'commercial viability' assumes that cheap oil will continue to be available.

Cheap oil makes the production of biofuels on a large scale relatively easy.

How about when cheap oil is no longer available Roger?

Just for arguments sake that oil energy was so expensive that many farms had to return to beast of burden energy. And the a biofuel industry had to be built up on the back of beast of burden energy in the same way that oil energy economy was slowly built up.

Given that biofuels appear to have a very low EROEI compared to oil when it was first exploited on any scale, would we be able to re-build our economy to the same level as we did with oil.

And let's remember that the global population is at least trippled from what it was when oil was first exploited.

I am not saying that biofuels are not viable primary energy sources perse, merely that they are not viable primary energy sources for our current global population of 7-8 billion.

The switch to biofuels will have to be complemented by any and all efforts to reduce the global population and convince particularyl woman to reduce their fertility to replacement level or less.

Biofuels are a part of the solution, not the entire solution.

If you look elsewhere on this page, you might see that I have also written:
"Personally, I think it's a bit daft to use any food crop for biofuel; by the same token, it is a lot daft to clear forest for biofuel.
"It makes a great deal more sense to produce biofuels microbiologically, with priority given to extracting the energy content from waste streams such as urban wastewater and land fill.
"In turn, if the biofuel is then used in fuel cells, then the waste CO2 can be supplied to (more) photosynthetic microbes."

The quote you give is excellent, except that it completely neglects TECHNOLOGICAL PROGRESS ie people learning better smarter more efficient ways to do things.

1) Great big vats of algae get heaps of solar energy for free.

2) Educated, emancipated women with access to health care generally choose to limit the number of children they have anyway.

Thanks Roger. I realise that mallee forestry has potential carbon fixing and biofuel potential, but have not been keeping up with progress.

Mallee forestry is consistent with avoiding diversion of food crops for biofuels.

For Greg's sake, does the article discuss mallee EROEI?

Roger's reference gives an EROEI for mallee of ~40.

I understand this to mean that a mallee biofuel operation can be energetically self-sustaining, exporting 39 parts in 40 (ie 97.5%) of its fuel production.

Biofuels may or may not be only part of the mix of renewable energiy Arthur, but it is irrelevant to the issue.

All the figures I have found online to date for the EROEI of any renewable energy source you care to consider some where around 10 or less.

Regardless of the mix, it would appear that the total amount of surplus energy avaliable for economic activities, other than generation of that energy, will be substantially less than that which we enjoyed throughout the 20th century during oil energy's heyday.

"Great big vats of algae get heaps of solar energy for free"

Again you are ignoring the fact that oil has been IMMEDIATELY available in vast quantities simply by sinking a well into the ground.

Those great big vats of algae require significant amount of time to generate the same volume of fuel that an oil well can deliver immediately.

This means that great big vats of algae will not be capbale of generating the same volume of liquid energy at the same rate.

With the same result that out civilisation will have signifciantly less energy available for economic activity.

Would you care to provide a link to the specific document where it states this EROEI value.

Perhaps our differences lie in that I am thinking in terms of decades, and you are thinking of the next couple of years?

Greg,

Talking of the fertility of women and trying to persuade them to have fewer children, I found this interesting:
http://www.spiegel.de/international/world/the-great-contraction-experts-predict-global-population-will-plateau-a-795479.html

Arthur is does not matter if we are talking decades or years.

If the EROEI of an energy source is signficantly lower than that of oil then it will NEVER be able to supply the same amount of energy at the same rate.

Consider this analogy Arthur.....

You start of with a job earning $1,000,000 per annum and purchase a 1000 square house on a 10 acre property that has a staff of 10 to maintain it all. Then there is electricity consumption, council rates,.......

You loose your $1,000,000 per annum job and get another job earning $30,000 per annum.

What you are effectively arguing Arthur is that in 20 years time you would be able to afford the up keep of the property and all the staff wages.

This is ludicrous. The fact is it does not matter how long you work at this lower paid job, you will NEVER be able to afford the house.

As is the case with lower grade renewable energy sources and our current economy and standard of living.