Biofuels

Biofuels have been championed as environmentally-friendly sources of power that help to tackle climate change. However, the report by the Organisation for Economic Cooperation and Development (OECD) said biofuels may "offer a cure that is worse than the disease they seek to heal".

Introduction

Concentrations of greenhouse gasses (GHGs) in the Earth’s atmosphere have also become a global concern because of their potential to result in long-term climate changes. About 82% of US GHG emissions are from combusting fossil fuels used to generate electricity and operate vehicles, and the other emissions are from methane, (Applied Energy, Volume 71, Issue 1, January 2002,Pages 15-30).On another hand, US agriculture’s contribution to air pollutant as a consumer of energy is small, as agricultural crop, livestock and poultry production accounts for only about 1% of direct energy use. However, the production agriculture accounts for about 7% of annul net GHG emissions (US Department of Agriculture, 2004a). Increase in agricultural productivity and conservation can reduce energy intensity of agricultural production and pollution. Recent studies show that replacing fossil energy with renewable energy, like biofuels, is an important way of reaching the climate policy goals. (Soil and Tillage Research, Volume 61, Issues 1-2, August 2001, Pages77-92).There is a significant opportunity to reduce pollutants and GHG emission by using biofuels. Like biodiesel, biofuels have many desirable environmental properties. They are non-toxic, biodegradable, and biodiesel exhaust emits less toxic air emissions, carbon monoxide and particular matter than petroleum diesel (Graboski and McCormick, 1998). Biofuels also have advantages that the plants grown each year to produce the fuel sequester carbon, which offsets the carbon released during fuel combustion (National Renewable Energy Laboratory, 1998).

Types of biofuels

First generation biofuels

Bioethanol, the most commonly biofuel feedstock, is a fuel generally produced by the action of microorganisms and enzymes through the fermentation of any biological feedstock, which contains appreciable amounts of sugar or materials that can be converted into sugar such as starch or cellulose.

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Second generation biofuels

Case Study—Biofuels in China

Biofuels have become a broad debat in many countries' energy policies since it covers many aspects, such as energy security, food security, climate change mitigation, and international biofuel developmaent. With 20 percent of world's population and 10 percent of its arable land, the center debate of biofuel prodution ins China is the confict between food security and energy crops. In January 2007, China’s State Forestry Administration (SFA) and the oil company PetroChina signed an agreement of developing deversity of potential energy crops,an oil-bearing plant, Jatropha. Jatropha curcas has considered as a high potential biodiesel feedstock in China since it grows on marginal land in Southwest China, and thus aviods the completion with food system. Southwest China, including Guizhou Province, Sichuan Provice, and Yunnan Provice, is the official target area for Jatropha prodution in China. Estimate Current and Planned Jatropha Area in Southwest China by Province

Future studies

The amount of subsidy, the extent of biofuel penetration into the energy market and the rate of technical progress are the key considerations in the future biofuel prospects. In this study, the only form of subsidy considered is in the form of a carbon price which may not be subsidy at all but rather a reflection of the future externality cost of GHG emission into the atmosphere. Namely, if a prospect offset 95% of the carbon created from energy equivalent amount of fossil fuel then at a US$40/MT carbon price this amounts to a US$38/MT implicit subsidy and relative to a wood price in the vicinity of US$25 to US$30/MT, this substantially offsets the purchase price to a biofeedstock user(Agiculure as a Producer and Consumer of Energy, J.Outlaw,2005). Energy market penetration of biofuels is similarly important. Biofuels can penetrate when new plants are built or older plants are retrofit. New power or petroleum refining plants are needed as existing plants are retired or as demand for energy use grows(Potential for Biofuel-based Greenhouse Gas Emission Mitigation:Rationale and Potential,2004). Therefore,progress in biofeedstock yields whether at the farm or in the form of conversion ratios to energy products as energy products will be important to maintain a competitive role.