Counter to other, alternative fuel analysis, Crutzen and colleagues question whether growing and burning many biofuel crops actually may raise, rather than lower, greenhouse gas emissions.
Alpha Galileo reports on a new study by Paul Crutzen. Best known for his Nobel prize winning work on the study of the ozone layer, Crutzen and colleagues have calculated that the amounts of nitrous oxides released by growing some of the most commonly used biofuel crops is around twice the amount previously thought – “wiping out any benefits from not using fossil fuels and, worse, probably contributing to global warming.”
For rapeseed biodiesel, which accounts for about 80 per cent of the biofuel production in Europe, the relative warming due to nitrous oxide emissions is estimated at 1 to 1.7 times larger than the relative cooling effect due to saved fossil CO2 emissions. For corn bioethanol, dominant in the US, the figure is 0.9 to 1.5. Only cane sugar bioethanol – with a relative warming of 0.5 to 0.9 – looks like a better alternative to conventional fuels.
This blog previously observed, with so much ongoing funding for biofuels, that it is a bit difficult to find scientific study in Europe or North America that questions the push for alternative fuels. The study of N2O release from agro-biofuel production by Crutzen, et al, which is currently subject to open review in the journal Atmospheric Chemistry and Physics, thus is important because it critiques the current wisdom of European policy to set standards for the use of biodiesel.
Crutzen’s work highlights the importance of establishing correct full life-cycle assessments for biofuels.
The U.S. Department of Energy and the U.S. Department of Agriculture had published the results of a three-and-a-half-year study, Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus (PDF), which was to provide a comprehensive “cradle to grave” environmental comparison of the two fuels in order to compare the total “life cycle” costs and benefits of each. The life cycle inventory considered energy resources consumed during production, manufacture, transportation and distribution.
The total fossil energy efficiency ratio used in the study was total fuel energy / total fossil energy used. Since biodiesel and petroleum diesel have very similar energy value, the study showed that biodiesel had an energy efficiency four times greater than that of petroleum diesel. It also demonstrated an advantage over ethanol, because the energy value of ethanol is about three-quarters the energy value of petrol.
The DOE / USDA study also examined air, water and solid waste emissions generated by petroleum diesel fuel and biodiesel. While the biodiesel lif cycle inventory included a consideration of NOx emissions, it focused on the reduction accomplished by blending over 100% RME (rapeseed methyl ester) during combustion.
- Soil
- The unconsolidated mineral matter on the surface of the Earth that has been subjected to and influenced by genetic and environmental factors of parent material, climate, macro- and microorganisms, and topography, all acting over a period of time and producing a product that differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics.
The level of N2O emissions is one indicator of the human influence on the atmosphere during the Industrial Era, i.e., the increasing concentration of nitrous oxide is anthropogenic.
Microbes convert much more of the nitrogen in fertilizer to nitrous oxide than previously thought – 3 to 5 per cent, according to Crutzen and colleagues. Their results contradict “the widely accepted figure of 2 per cent used by the International Panel on Climate Change (IPCC) to calculate the impact of fertilizers on climate change.”
As release of N2O affects climate and stratospheric ozone chemistry by the production of biofuels, much more research on the sources of N2O and the nitrogen cycle is urgently needed…Here we concentrated on the climate effects due only to required N fertilization in biomass production and we have shown that, depending on N content, the use of several agricultural crops for energy production can readily lead to N2O emissions large enough to cause climate warming instead of cooling by “saved fossil CO2”. What we have discussed is one important step in a life cycle analysis, i.e. the emissions of N2O, which must be considered in addition to the fossil fuel input and co-production of useful chemicals in biofuel production.
We have also shown that the replacement of fossil fuels by biofuels may not bring the intended climate cooling due to the accompanying emissions of N2O. There are also other factors to consider in connection with the introduction of biofuels. We have not yet considered the extent to which the high percentage of N-fertilizer which is not taken up by the plants, and the organic nitrogen in the harvested plant material, may stimulate CO2 uptake from the atmosphere; estimates for this effect are very uncertain. We conclude, however, that the relatively large emission of N2O exacerbates the already huge challenge of getting global warming under control.
Some of the GCC discussion focused upon the need for materials manufacturing as well as fuel. Still most of the commentary focused on biofuel production and GHG emissions by the agriculture sector.
GCC commentator Jim G. asked some incisive, albeit rhetorical, questions:
- Isn’t it true according to the above that, for levels of nitrogen oxides to be greater tomorrow than they are today, we’ll have to either use more nitrogen compounds per acre on existing farmland, or boost the quantity of farmland under cultivation?
- Assuming boosting the quantity of land under cultivation is more likely, biofuels can only be deemed a significant cause of trouble if they take up a significant quantity of that land.
But then there’s the “food versus fuel” argument, standing in contradiction to this, i.e., the claim that there is a limited quantity of arable land, and that more biofuels will result in less food.
So if we had 50% biofuels use on arable land under cultivation, and we decided to stop doing so because it produced nitrogen oxides, would we instead let the land lie fallow again? Probably not. And then our nitrogen problems are the same as they were. So if there is a zero-sum relationship between food and fuels, it seems to be that’s a much more serious problem.
- But if, as pointed out by others, second generation feedstock require no fertilizers, this latter threat diminishes significantly.
Does anyone know if net land under cultivation increases over time as food demand increases? This certainly isn’t true in the USA, but it could be true globally, no?
“So, not to worry. Biofuels will not be derailed, just slowed to sustainable level of growth.”
So, is “sustainability” the new, Big Farm catchphrase, like democracy is for Big Oil?
Pursuant to a previous reference by Green Car Congress to a UN Report, i.e., the livestock sector generates more GHG emissions than the transport sector, GCC commentator Andrey provides a comprehensive summary of concerns about GHG emissions from the agriculture sector:
Agriculture emits much more GHG than combustion of fossil fuels, it is well researched and well downplayed fact. To put numbers into perspective, just released research estimates CO2 emissions from human respiration being 0.6 GT carbon per year, domesticated animals respiration releases 1.5 GTC, plus 1 GTC from decomposition of human and domesticated animals waste; total 3.1 GTC per year. Compare it to 7 GTC emitted by combustion of fossil fuels. Presented numbers do not include huge emissions of methane from domesticated animals farting and belching (regular cow emits close to 600 liters of methane daily), and emissions of GHG associated with growing food for humans and feed for animals.
Politicians do not really give a hood about it. Initial intentions to address GW readily deteriorated into meaningless campaign to tax emissions of CO2 from fossil fuel combustion – no more no less. Examples are plenty:
GHG emissions of New Zealand cattle (farting & belching!) accounts for 60% of total country GHG emissions, and NZ addressed the issue by imposing this week cup™ system on emission of CO2 from fossil fuel combustion;
Diesel engines contribute to warming more than comparable gasoline engines (due to emissions of Black Carbon –diesel soot, which is very potent heating agent), but European politicians prefer to overlook it and promote diesel proliferation to reduce their addiction to Middle East oil.
Russian natural gas supplied to Europe emits more GHG than, say, use of Polish coal (due to no less than 5% of NG venting in Russia NG industry; NG (methane) is 23+ times more potent GHG than CO2), yet Europe increases import of this clean-burning and convenient HC fuel.
Same with US corn ethanol. It barely has positive EROI, and considering that distillation is almost universally is fueled by coal, and taking into account N2O and soil organic decomposition CO2 emissions during corn growing, corn ethanol is substantial net contributor to GW.
It just happened that corn ethanol is extremely beneficial from other points of view: good PR, reduction of oil import, best invented way to subsidize rural America, good leverage to keep corn prices from periodic collapses, improved food security (25% of corn harvest used to produce corn ethanol in US could be easily switched to food&feed in case of emergency).
My estimations are that corn ethanol in US will reach about 10% of current US gasoline consumption by volume, substituting up to 5% of crude oil demand. Further increase will be slow, but steady: increased corn yields, optimized to fuel production corn hybrids, GM yeasts, cellulosic ethanol, etc. This number will be much higher for Brasil, and much lower for Europe.
Reference
P. J. Crutzen, A. R. Mosier, K. A. Smith, and W. Winiwarter. “N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels.
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It is important to study the issue of biofuels with greater care, says expert consultants to APEC. Caution is urged relative to the current rush toward major decisions on biofuel policies. There is greater need for “solid research and unbiased information about their potential benefits, impact, and risks.” Gee, Mike, mo’ study, eh?
Key conclusions from the Expert Consultation on Biofuels are as follows:
The Bioenergy Revolution is fast approaching. Biofuels will play a major role in the global economy of the future. Many countries are exploring different strategies and policies on alternative energy sources, and the Asia-Pacific region, in particular, is expected to play a significant role in the development and promotion of biofuels.
Poverty is still widespread in Asia. It is not clear to what extent poor farmers will benefit from the Bioenergy Revolution. What is clear is that the introduction and/or expansion of biofuel crops will cause major land-use changes, and that many feedstocks (although originally targeted at marginal lands) will compete with food crops in productive eco-regions. The challenge is to ensure a balance between food and biofuel production.
Policymakers need to protect the poor from rising commodity prices likely to be triggered by the diversion of crop produce or area expansion of biofuel crops. Therefore, there is an urgent need to strengthen policy research in order to avoid decisions that may lead to competition between food and bioenergy, and identify a complementary approach that benefits both sectors.
International organizations and the international agricultural research centers (IARCs) must accelerate their biofuel-related research in order to generate much-needed international public goods (IPGs) that will benefit resource-poor farmers. They also need to enhance regional coordination of R&D efforts on bioenergy in the Asia-Pacific region, encourage regional information sharing, and facilitate research networking and capacity building of NARES.
Public-sector research needs to ensure that technology advances made in the private sector ultimately benefit the poor in the developing world. This is particularly important for many second-generation biofuel technologies, which, for want of proper policies and IPR regime, may not be accessible to poor farmers in Asia. Public-private partnerships, being the key factor, will have to be established and promoted.
It is critical that scientists examine and share unbiased information on the life cycle performance and economics of bioenergy technologies, and their impact on food security and poverty. The social and environmental impacts of these technologies will also have to be assessed. This requires a standardized typology of food-feed-fiber-energy–producing agricultural systems as well as standardized methodologies for their integrated assessment.
Asian countries should consider the use of crop residues, especially rice and wheat straw, which are largely being burned in most countries. This is a priority area for R&D, particularly with regard to thermal conversion technologies for different scales and the level of residue retention, which may be needed for sustainable land use under different cropping systems.
Potential biofuel-producing countries in Asia should conduct their own national assessments critically and devise appropriate strategies to meet long-term bioenergy goals. APAARI and other regional/global organizations should devise strategies for the Bioenergy Revolution, and sensitize policymakers so that Asia-Pacific countries can reap the expected benefits.
The donor community should fund new R&D efforts on bioenergy, since the long-run benefits will lead to both poverty alleviation and protection of the environment – thus meeting two of the major Millennium Development Goals.
Ed Roast tells us:
Simon Donner provides a thoughtful critique of the paper and why he and most other scientists studying GHG impact accept the lower value the rate of 1-2% used in previous models. Put simply, Donner contends that no actual physical evidence exist for the 3-5% rate.
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[...] is that farmers want to grow more corn. The consequences could include more fertilizer runoff and nitrous oxide released into the atmosphere, in addition to a greater demand for petroleum, both as fuel and petrochemicals used in [...]