Biofuels and their carbon cost

 As we are running out of fuels that we find by digging deep into the earth where they have rested for hundreds and thousand of years locking huge amounts of carbon dioxide away from the atmosphere, and as our world’s population increases to more than 6.6 billion souls each of them expecting and working for a better life, so we are growing the fuel we need as a cheaper and more environmentally beneficial way than using resources that will be exhausted in the lifetimes of our great grandchildren.  But what will the consequences of increased use of biofuels be? Will they be benign or are we storing up another set of problems for new generations?

The United States of America, great user of fuel, last year passed a law, the Energy Independence and Security Act, which calls for biofuel production to reach 36 billion US gallons by 2022. It is expected that this strategy will reduce carbon emissions by 50%.

Even though this initiative seems to have had the effect of making food prices more expensive, the biofuel band wagon rolls on as though transport was more important than food.

The prestigious Science magazine has recently published two articles that question the benefits of biofuels. They both conclude that it is important to grow the right biofuels in the right place; otherwise the carbon emissions created exceeds those saved by a significant margin. In other words biofuels in the wrong places have a worse effect to our carbon balance than coal.

You can calculate the carbon emissions of clearing a piece of land and then compare it with the carbon saving by planting that land with biofuels. The carbon cost is produced by a number of factors, including the release of carbon stored in the soil. You only get a net carbon benefit after you repay the original carbon cost of land clearing.

In “Land Clearance and the Biofuel Carbon Debt” the authors (Messrs Hill, Tilman Polasky & Hawthorne) conclude that if you clear tropical lowland forest in South East Asia, you immediately release many tonnes of carbon. If you then plant it with palm oil trees, as many such clearances have been planted with, and use the palm oil to replace petrol and diesel fuels, you need 86 years to produce enough biodiesel to compensate for the original cost of carbon that you have released. If you clear tropical peat land you need 840 years to repay the carbon cost.

This means that planting biofuels gives us an immediate carbon problem that takes a lifetime or more to recover from. On this basis you cannot claim that planting tropical forest with palm oil trees is doing anything but adding to the emissions in the atmosphere and increasing the rate of climate change.

At the best end of the scale, if you plant sugar in Brazil to produce ethanol (but not in the tropical rain forest) the carbon cost 17 years, still a considerable period of time.

The second paper produced by a group of Princeton University researchers was called “Uses of US Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Change Use”, and its title sums up its conclusion. In essence this suggests that there is an indirect, hard to measure increase in emissions; if you change a food crop in one place to a biofuel crop, then you have to plant new land with food crops elsewhere, because we all need food. This creates more carbon emissions out of the soil, which are not compensated for. The researchers’ modelling suggests that land switched from food production to corn for ethanol production will double emissions compared with simply continuing to use petrol and diesel fuel.

It is possible to grow biofuels in a way that is less carbon intensive, by for example, choosing fast growing crops with very high yields. The problem here is that we do not know enough to be able to do this. As usual humans are adopting a gung ho approach on the basis that it will be all right in the end.

The best thing is to use less fuel. No one is entitled to drive a high emission vehicle as a matter of right. Indeed, there may well come a time in the not too distance future when car engine sizes and consumption is so strictly regulated that the four wheeled drives and the high performance cars will be as extinct as the dinosaurs; if not we may well be extinct ourselves.

2 Responses

  1. Hello!
    Very Interesting post! Thank you for such interesting resource!
    PS: Sorry for my bad english, I’v just started to learn this language 😉
    See you!
    Your, Raiul Baztepo

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