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Explainer: what are biofuels?

Since the beginning of civilisation, humans have depended on organic materials - or “biomass” - for cooking and heat. Many developing countries in Asia and Africa still do. Biofuel or bioenergy is the…

Canola is harvested on a property near Wallendbeen NSW. AAP Image/Alan Porritt

Since the beginning of civilisation, humans have depended on organic materials - or “biomass” - for cooking and heat. Many developing countries in Asia and Africa still do. Biofuel or bioenergy is the chemical energy contained in biomass that can be converted into direct, useful energy sources using biological (including food digestion), mechanical or thermochemical processes.

The current liquid biofuels (bioethanol and biodiesel) are mainly produced from first generation feedstocks (such as sugarcane, maize, rapeseed) and constitute only a small fraction (1%) of present transportation energy. Second generation biofuels will come from dedicated perennial energy crops (such as miscanthus, switchgrass, agave, pongamia), and in the near future, hydrogen gas may be produced from algae, bacteria, or artificial photosynthesis to fuel hydrogen-cell powered cars.

Liquid biofuels

Liquid biofuels are most familiar to us. Bioethanol is a substitute for gasoline and biodisesel is a substitute for diesel.

Most cars that are built have internal combustion engines which can only burn liquid fuels. While other types of engines, such as electric and hydrogen fuel cells are being developed, in the meantime, liquid biofuels are the transition renewable alternative to fossil fuels for transport.

According to the International Energy Agency, liquid biofuels account for only 2% of total bioenergy, and they are mainly significant in the transportation sector. Transportation accounts for 28% of global energy consumption and 60% of global oil production, and liquid biofuels supplied only 1% of total transport fuel consumption in 2009.

Globally, liquid biofuels can be classified into three main production sources; maize ethanol from the United States, sugarcane ethanol from Brazil and rapeseed biodiesel from the European Union. There is also a small quantity of palm oil biodiesel from Indonesia.

In 2010, Brazil and the United States produced 90% of the 86 billion litres of global bioethanol and the European Union produced 53% of the 19 billion litres of biodiesel.

Biofuel production trends UNEP GRID 2011

In Australia, biodiesel is being produced from used cooking oil (an agricultural by-product), tallow and canola seed; and bioethanol is produced from sugarcane molasses, grain sorghum and waste wheat starch.

Not so sustainable

The first generation of biofuels produced from starches, sugars and oils of agricultural food crops, including maize, sugarcane, rapeseed (including canola) and soybean have faced disfavour for competing with food and feed production.

Hypothetically, if all the main cereal and sugar crops (wheat, rice, maize, sorghum, sugar cane, cassava and sugar beet), representing 42% of global cropland, were to be converted to ethanol, this would correspond to only 57% of total petrol use in 2003, and leave no cereals or sugar for human consumption (although the reduced sugar in the human diet would have health benefits).

These first generation biofuels also have large carbon and water footprints. Greenhouse gas emissions during agricultural production of biofuel crops contribute 34-44% of the greenhouse gas balance of maize ethanol in the United States and more than 80% in pure vegetable oils. In general the water footprint of biofuels is two to five times larger than the water footprint of fossil fuels.

Clearing undisturbed native ecosystems such as rainforest, savanna and grassland for biofuel production also increases net greenhouse gas production due to a change in land use.

The way forward

Due to food and energy security concerns, many countries are promoting biofuel crops that can be grown on land not suited for food production, so that the two systems are complementary rather than competitive.

Second generation biofuels refer to the range of feedstocks (dedicated energy crops such as miscanthus, switchgrass, pongamia, agave, Indian mustard, sweet sorghum, algae, carbon waste), conversion technologies (fast pyrolysis, supercritical water, gasification), and refining technologies (thermo-chemical Fischer-Tropsch methods) used to convert biomass into useful fuels.

For example, Swiss company Clariant opened a ligno-cellulosic plant in Germany in 2012 that can produce up to 1000 tons of cellulosic ethanol from 4500 tons of wheat straw.

Hydrogen is designated as a third generation biofuel, when it is produced from biomass by algae or enzymes. Hydrogen contains three times the energy of petrol on a mass basis and its combustion produces only water, although future technological breakthroughs are needed before hydrogen can be produced economically.

One method of hydrogen production is artificial photosynthesis which involves mimicking natural systems using molecular photocatalytic systems for light-driven water oxidation and hydrogen production.

Artificial photosynthesis was only an academic activity until the development of the first practical artificial leaf. It is claimed to be potentially 10 times more efficient in photosynthesis than a natural leaf, however commercialisation of artificial photosynthesis is yet to be proven.

An “artificial leaf” made by Daniel Nocera and his team at MIT

Join the conversation

20 Comments sorted by

  1. Robert Merkel

    Lecturer in Software Engineering at Monash University

    It's worth noting that the "second generation biofuels" have been in development for quite some time now, and still haven't managed to be commercialized in any significant way. They remind me of fusion power, only always five years away rather than thirty.

    Many of the alternative plants proposed for biofuel production have also proved problematic. For instance, they can grow in marginal soils, and produce a lot of biofuel, but not at the same time. Some are highly invasive weeds.

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    1. David Arthur

      resistance gnome

      In reply to Robert Merkel

      Biofuels won't really take off until the world gets serious about ceasing fossil fuel use.

      Whether or not this predates Rupert Murdoch's departure from this world is a matter of some conjecture.

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    2. David Arthur

      resistance gnome

      In reply to Robert Merkel

      "Many of the alternative plants proposed for biofuel production have also proved problematic. For instance, they can grow in marginal soils, and produce a lot of biofuel, but not at the same time. "

      Algae. Have a read of Julian Cribb's article in the April 2013 edition of Australasian Science.

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    3. Jane Rawson

      Editor, Energy & Environment at The Conversation

      In reply to David Arthur

      I should say, we have a piece coming explaining algal biofuels in the next week or two. We're trying to get explainers of all alternative energy sources.

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    4. Robert Merkel

      Lecturer in Software Engineering at Monash University

      In reply to David Arthur

      Haven't read Julian Cribb's article, but I've heard about biofuel from algae for many years now.

      Lots of promises, lots of research and VC dollars, not much biofuel.

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    5. David Arthur

      resistance gnome

      In reply to Robert Merkel

      Lots and lots of research, agreed: Google biofuel at site:sciencedaily.com

      Not much biofuel, also true: market dominance by existing players.

      Try reflecting upon the inertia of large corporate players, with that inertia abetted by Denialist think-tanks and crusading anti-Commie media barons.

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    6. Doug Hutcheson

      Poet

      In reply to David Arthur

      "Try reflecting upon the inertia of large corporate players, with that inertia abetted by Denialist think-tanks and crusading anti-Commie media barons." Quite right, David. One wonders how much further down the road we would be if the nay-sayers had used their energies to develop alternative fuel sources, instead of oppose their development. We live in a world of strange priorities.

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  2. John Newlands

    tree changer

    I have run a vehicle mainly on WVO derived biodiesel for 6 years now with only just one major fuel system cleanout recently, not for 'dirt' but wax deposits. I now intend to install fuel preheating as a cold weather precaution. However biodiesel is clearly a niche product not a major substitute for petroleum.

    It is clearly better to make hydrocarbon fuels boosted by an external hydrogen source. If you've eaten margarine today you're part way there. If the carbon source was organic not fossil…

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  3. Tim Scanlon

    Debunker

    Henry Brockman investigated some interesting oil producing plants for biofuels. His work is worth looking up for anyone here interested.

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  4. James Hill

    Industrial Designer

    Urban green waste, which has a collection and disposal cost, seems to be a good match for secondary bio fuel from the reulting syngas with the remant material having some use surely.
    Councils would have a commercial interest to pusue such a technology and many progressive councils are already increasing their non-rates revenues in the face of the facts that houses do not actually produce the wealth necessary to pay rates, and a ageing population neither has the income to pay rates.
    The upshot of this argument is that councils need to produce wealth from their resources and council waste, green or otherwise, is a good feedstock for secondary bio fuels.

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    1. Doug Hutcheson

      Poet

      In reply to James Hill

      James, what is the return on investment for council biofuel production? Is it something a commercial operator could take on, by buying council organic waste and selling the end product? I live in a regional town, which might not have the critical mass needed for this technology to be viable, if it requires more waste than we actually generate. Interesting to consider, though.

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    2. James Hill

      Industrial Designer

      In reply to Doug Hutcheson

      Doug, the technology used by Linc Energy in Chinchilla, Qld is said to be modular for easy expansion.
      In that case secondary Bio diesel is made from coal.
      Presumably these modular units may be of a size that is appropriate for your local council.
      The resulting diesel is called "Green diesel" to the horror of modern day Luddites, and is a pure clear liquid and was mandated for the Athens Olympics in that city to reduce the smog from petroleum Diesel.
      The Chinchilla plant produces diesel for 30c/litre…

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  5. Brad Wells

    logged in via Facebook

    Thanks Daniel. A recent article "Revving up on ethanol" in Brazil Talk (pp.14-17, Issue 5, 2013) confirms Brazil's belief in what they consider as sustainable ethanol from sugarcane; driven from business investments with significant government support. Here's hoping they see the value in more efficient means of biofuel production before the food situation becomes too critical.

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  6. Alex Cannara

    logged in via Facebook

    Good to see more exposure of biofuel 's inherent wastefulness and inefficiency.

    However, the basic premise, of burning anything for power, is faulty and a net GHG emitter.

    Even if artificial photosynthesis were achieved at ~70% efficiency, sunlight just provides 1kW per square meter. That means the present efficiency of natural photosynthesis (~7%) being improved 10x would give a potential chemical energy storage of ~700W x sunlit hours, or maybe 4kWHrs per day per sq meter.

    That 4kWHr/day/sqm…

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    1. Doug Hutcheson

      Poet

      In reply to Alex Cannara

      "There's no need for combustion for anything but home heating and aircraft power, etc." What about farm equipment, construction machinery, ocean transport, Alex? I doubt PV is yet able to provide power for these heavy machines and nuclear, while an important part of the future energy mix, is only suited to installation in large structures, such as ships. We have to face up to the probability that we cannot continue with Business As Usual in a warming world. We need to adapt, in part by changing the way we live.

      We need to take responsibility for our adverse impact on this fragile planet. BAU is not an option.

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    2. James Hill

      Industrial Designer

      In reply to Doug Hutcheson

      Many years ago a British NGO developed a safe boiler for steam powered vessels on the Congo.
      This was to allow the users to source their fuel from the forest, sustainably, rather than buying petroleum with money they did not have.
      The major problem was that produce which was raced to the markets early got the best price and this inspired the users of steam propulsion to weld up their safety valves to achieve greater power at higher pressures and temperatures but at the risk of blowing themslves…

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  7. Kenneth Mazzarol
    Kenneth Mazzarol is a Friend of The Conversation.

    Retired

    I believe Hemp can save Earth from the ravages of the destructive masculine beast if only the masculine beast could be made look at the big picture.

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  8. Mike Jubow

    forestry nurseryman

    In the next few weeks, I will be doing our first scaled up yield trial from a plant we are growing to see how many litres of 'crude' oil per hectare we are going to get from a plantation just on nine months since planting. This is from a plant that can grow in lower rainfall belts than food crops and so will not compete with the land for food growing. This crop will not need replanting after harvesting as it re-grows quite readily and it rarely produces viable seeds, eliminating the risk of going…

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  9. Optimistic Alex

    Garbologist

    No mention of waste based fuels? Really? What about refused derived fuel? What about pyrolysis of green waste and plastics? Not mention of landfill gas or anaerobic digestors? Really?

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