一項新的研究表明，生物燃料的生產(chǎn)可能會增加溫室氣體的排放,。該研究的第一作者,、諾貝爾獎獲得者Paul Crutzen和來自歐美的同事認為,，生產(chǎn)生物燃料作物所需的氮肥可能導致比人們此前所認為的更大數(shù)量的一氧化二氮排放到大氣中。
根據(jù)這項研究,，微生物把化肥中的3%到5%的氮轉化成了一氧化二氮,，而不是政府間氣候變化委員會所估計的1%。
一氧化二氮是一種主要的溫室氣體,，在100年的尺度上,，它影響全球變暖的潛力是二氧化碳的296倍。
油菜籽產(chǎn)生的一氧化二氮導致的全球變暖,，其數(shù)值是由于節(jié)省相應的化石燃料二氧化碳排放導致的“變冷”效應的1到1.7倍,。對于玉米，這個數(shù)字是0.9到1.5,，這表明或許應該繼續(xù)使用石油而不是生產(chǎn)和燃燒生物燃料,。
甘蔗是唯一一種表現(xiàn)出可以讓溫室氣體排放凈減少的作物，因為它需要的化肥少于其他生物燃料作物,。
巴西是世界上最大的甘蔗生產(chǎn)國,，它已經(jīng)在乙醇制造和生物燃料使用上進行了大量投資。根據(jù)巴西地理與統(tǒng)計研究所的數(shù)據(jù),，在2006-2007年,，巴西的甘蔗產(chǎn)量已經(jīng)達到了4.25億噸。
巴西農(nóng)業(yè)氣象與氣候研究中心的農(nóng)業(yè)工程師兼研究員Jurandir Zullo Jr說Crutzen等人的研究意義重大,，但是在計算生物燃料的溫室氣體排放的時候,，還需要考慮其他許多因素，包括從化學因素,、社會因素到經(jīng)濟因素,。
他還說如果這些結論得到了證實，那么它將會進一步鼓勵巴西的甘蔗生產(chǎn),。然而,，甘蔗種植面積的擴張可能進一步鼓勵森林砍伐，而森林的減少也會造成全球變暖,。
該研究發(fā)表在了《大氣化學和物理學》雜志上,。
原始出處：
Atmos. Chem. Phys. Discuss., 7, 11191–11205, 2007
N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels
P. J. Crutzen1,2,3, A. R. Mosier4, K. A. Smith5, and W. Winiwarter3,6
1Max Planck Institute for Chemistry, Department of Atmospheric Chemistry, Mainz, Germany
2Scripps Institution of Oceanography, University of California, La Jolla, USA
3International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
4Mount Pleasant, SC, USA
5School of Geosciences, University of Edinburgh, Edinburgh, UK
6Austrian Research Centers – ARC, Vienna, Austria
Received: 28 June 2007 – Accepted: 19 July 2007 – Published: 1 August 2007
Correspondence to: P. J. Crutzen ([email protected])
Abstract
The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, using known global atmospheric removal rates and concentration 5 growth of N2O as a proxy for overall emissions. The relationship, in both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production and deforestation, is consistent, showing an overall conversion factor of 3–5%. This factor is covered only in part by the 1% of “direct” emissions from agricultural crop lands estimated by IPCC 10 (2006), or the “indirect” emissions cited therein. This means that the extra N2O entering the atmosphere as a result of using N to produce crops for biofuels will also be correspondingly greater than that estimated just on the basis of IPCC (2006). When the extra N2O emission from biofuel production is calculated in “CO2-equivalent” global warming terms, and compared with the quasi-cooling effect of “saving” emissions of 15 fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species have more favourable climate impacts. This analysis only considers the conversion of biomass to 20 biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle assessment.
Pdf 全文鏈接：
http://www.atmos-chem-phys-discuss.net/7/11191/2007/acpd-7-11191-2007.pdf
