‘Carbon debt’ created by some biofuels must be considered in sustainability debate, new study shows

Soybean crops were found to have the shortest carbon debt repayment time. Photo courtesy of Ryan/flickr.

DURBAN, South Africa (30 November, 2011) _ Despite being heralded as a green alternative to fossil fuels, a new study by the Center for International Forestry Research (CIFOR) has found that carbon emissions generated from land conversion for biodiesel production may take decades to hundreds of years to reverse in some cases, raising serious questions about biodiesel sustainability.  This large variation is the result of the type of land converted and the productivity of the feedstock crop.

Published work by CIFOR and others suggests the need for a “full life-cycle analysis”, that takes into account the carbon debt of land-use change, to become commonplace when assessing the environmental benefit of biofuel usage.

“It really matters how you produce biofuels and what land you grow it on as to whether you are going to get climate change benefits,” said Louis Verchot, CIFOR scientist and co-author of Implications of Biodiesel-Induced Land-Use Changes for CO2 Emissions: Case Studies in Tropical America, Africa, and Southeast Asia published in a special feature of Ecology and Society.

“Biofuels that result in the conversion of natural ecosystems are never going to be emission efficient. This study argues for appropriate spatial planning and being aware that anything that you do in the name of the atmosphere could have unanticipated consequences unless you look at the whole production system.”

Fluctuating oil prices and growing concerns about climate change have led to a renewed commitment to renewable energy, with demand for biofuels such as those produced from palm oil, jatropha and soy increasing in recent years.

However, despite their potential for climate mitigation, biofuels have been receiving growing negative attention because their expansion often leads to deforestation, negative social impacts for customary land users such as loss of land and labor rights, threats to food security, and high carbon emissions from land-use change.

To quantify the atmospheric effects on biofuel-related changes in land use, CIFOR scientists examined actual case studies for the production of three biodiesel and multi-purpose feedstocks in sites in Asia, Africa and Latin America. They calculated emissions from both direct land-use change (land clearing for making fields), and assessed plausible ranges to anticipate indirect land-use change (when production of biofuels pushes other agricultural activities further into natural ecosystems).

These emissions were considered to be the “carbon debt” that was created in the biofuel production chain, and this debt must first be repaid through reduced fossil-fuel use before there could be net benefits to the atmosphere.  CIFOR scientists then calculated the time it would take to repay the carbon debt of each system studied.

In most cases, the study found that significant carbon debts were created by the cultivation of biodiesel-only and multi-purpose feedstocks that would take tens to hundreds of years to restore. The best case was soybean production, for which carbon debt repayment times in some cases were less than 30 years.

The idea of carbon debt repayment is not new for biofuels. This study is the best effort so far to quantify the debt in the tropics and to look at repayment times for real world production systems. The strength of this work is in the comparisons between different feed stocks and different settings. “The take-home message,” says Verchot,  “is not that biofuels are bad for the atmosphere. Rather, the results point to important considerations that must be taken into account to make biofuels sustainable.”

These studies should help policy makers, in producer and consumer countries alike, understand what needs to be done to better guide and regulate the industry to achieve key policy aims, said Laura German, lead editor of the special issue.

“This set of papers suggests that neither rural livelihood nor climate mitigation benefits can be assumed, suggesting the need for more proactive efforts by producer and consumer country governments, industry and civil society to steer the sector in more sustainable and equitable directions.”

The impacts and implications of biofuel expansion on forests will be discussed at a CIFOR sponsored event at the Durban Climate Change and Trade Symposium in parallel to the United Nations Conference on Climate Change COP 17 in Durban, South Africa next week. Register here.

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  • Rex

    You say “land conversion for biodiesel production may take decades to hundreds of years to reverse in some cases” yet don’t mention the many other industrial crops grown – some explicitly just for vehicles like rubber. These industrial plantations are equally as bad for sustainability and land conversion loss of ecosystem services and biodiversity etc yet it’s always biofuel crops that are given a hard time. Rubber’s primary use is for car tyres and conveyor belts (and a variety of other minor uses) yet we don’t hear of any innovations seeking to displace rubber from our vehicles even though their ecological destruction of predominantly rainforest areas is as significant as any other tropical production system. According to UNCTAD, some 8.5 million hectares of land is dedicated to the production of rubber.

    How important, for example, is it for natural ecosystem functions and land management to have millions of hectares of coco grown purely to satisfy the sweet tooth of mainly developed world, or tea and coffee for similar reasons?

    Biofuel crops, like any crop, needs to be appropriately planned and managed. If a country has ideal growing conditions for a biofuel crop but not good enough for a rubber plantation, why are they given such a hard time?
    Why is there no call for a “full life-cycle analysis” of rubber, tea, coffee, sugar and the many other industrial food crops that also displace natural biodiversity, use water, soak up nutrients, use cheap labour, pay farmers pennies for each ton etc.?

    You say “Biofuels that result in the conversion of natural ecosystems are never going to be emission efficient …” yet fail to mention that this applies to all crops and not biofuel crops specifically.

    You suggest that “biofuels have been receiving growing negative attention because their expansion often leads to deforestation, negative social impacts for customary land users such as loss of land and labor rights, threats to food security, and high carbon emissions from land-use change” yet again without mentioning this applies to all arable crops regardless where they are grown.

    It’s probably time to delink biofuel production from the climate change debate even though compared to other industrial crops it probably has some value in mitigating global warming.

    • Louis Verchot

      Thank you for this comment. Let me first make the point that neither this study nor the authors are giving a “hard time” to any countries. The paper made no value judgment. The author of the comment has a valid point most deforestation or conversion of natural ecosystems for agricultural production creates emissions. With the addition of two billion new people to our population over the next 40 years or so, we can reasonably expect these emissions to grow. The author is also right that the expansion of plantation crops like rubber and cacao is often at the expense of natural ecosystems. Where we disagree with the author is on whether biofuels should be singled out for scrutiny with respect to their carbon footprints. The major impetus for the expansion of biofuel production is the concern over the impacts of fossil fuel burning on the climate system and policies that have been put in place to reduce them. Since biofuels are being produced specifically to reduce emissions, contrary to other crops, it is important to evaluate whether indeed they do reduce these emissions. It does not matter whether you intend it or not, if you shoot yourself in the foot, it still hurts. Likewise, if you mean to reduce emissions, but you inadvertently increase them, you will have a negative impact on the atmosphere.

      There have been several hypothetical studies that suggest that biofuels are not sustainable for emissions reductions because of the carbon footprint. We set out to put real numbers to the question and see whether this was true. In the handful of cases that we looked at, the emissions were greater than the fossil fuel savings. However, our study should not be seen as a condemnation of biofuels. We are sorry that doing biofuels right is harder than some people would like it to be. But our study actually points to how biofuels might be produced sustainably. This means avoiding conversion of natural ecosystems.

      Louis Verchot