Towards sustainable production and use of biofuels: Assessing Biofuels
The UNEP report "Assessing Biofuels" provides an overview of the key problems and perspectives toward sustainable production and use of biofuels. It is based on an extensive literature study, taking into account recent major reviews, and considering a wide range of different views from eminent experts worldwide. The focus is on so-called first generation biofuels while considering further lines of development. This focus is due to state-of-the-art and data availability until the end of 2008. Potential benefits and impacts of second and third generation biofuels – preferably referred to as 'advanced biofuels' – are partially included, and might be subject to a specific report at a later stage. The UNEP report "Assessing Biofuels" focusses on the global situation, recognising regional differences. In the overall context of enhancing resource productivity, options for more efficient and sustainable production and use of biomass are examined. In particular, "modern biomass use" for energetic purposes, such as biomass used for (co-)generation of heat and power and liquid biofuels for transport, are addressed and related to the use of biomass for food and material purposes. Whereas improving the efficiency of biomass production plays a certain role towards enhancing sustainability, progress will ultimately depend on a more efficient use of biotic (and abiotic) resources (incl. for instance, an increased fuel economy of car fleets), although a full consideration of all relevant strategies towards this end (e.g. changing diets high in animal based foods and reducing food losses) is beyond the scope of the UNEP report "Assessing Biofuels".
Important trends and drivers Current and projected use and potentials of biofuels
In developing countries, over 500 million households still use traditional biomass for cooking and heating. But already 25 million households cook and light their homes with biogas and a growing number of small industries, including agricultural processing, obtain process heat and motive power from small-scale biogas digesters. Biomass contributed about 1% to the total global electric power capacity of 4,300 GW in 2006. It is to a growing extent employed for combined heating and power (CHP), with recent increases in European countries and developing countries like Brazil. Many countries have set policy targets for renewable energy, but only a few specify the role of biomass. World ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52 billion litres, while biodiesel expanded eleven-fold from less than 1 billion to almost 11 billion litres. Altogether biofuels provided 1.8% of the world’s transport fuel. Recent estimates indicate a continued high growth. From 2007 to 2008, the share of ethanol in global gasoline type fuel use was estimated to increase from 3.78% to 5.46%, and the share of biodiesel in global diesel type fuel use from 0.93% to 1.5%. The main producing countries for transport biofuels are the USA, Brazil, and the EU. Production in the United States consists mostly of ethanol from corn, in Brazil of ethanol from sugar cane, and in the European Union mostly of biodiesel from rapeseed. Other countries producing fuel ethanol include Australia, Canada, China, Colombia, the Dominican Republic, France, Germany, India, Jamaica, Malawi, Poland, South Africa, Spain, Sweden, Thailand, and Zambia. Rapid expansion of biodiesel production occurred in Southeast Asia (Malaysia, Indonesia, Singapore and China), Latin America (Argentina and Brazil), and Southeast Europe (Romania and Serbia). Investment into biofuels production capacity probably exceeded $4 billion worldwide in 2007 and seems to be growing rapidly. Industry with government support also invests heavily in the development of advanced biofuels. International trade in ethanol and biodiesel has been small so far (about 3 billion litres per year over 2006/07), but is expected to grow rapidly in countries like Brazil, which reached a record-high of about 5 billion litres of ethanol fuel export in 2008. Policies have essentially triggered the development of biofuel demand by targets and blending quotas. Mandates for blending biofuels into vehicle fuels had been enacted in at least 36 states/provinces and 17 countries at the national level by 2006. Most mandates require blending 10–15% ethanol with gasoline or blending 2–5% biodiesel with diesel fuel. In addition, recent targets define higher levels of envisaged biofuel use in various countries. Regarding the global long-term bioenergy potential, estimates depend critically on assumptions, particularly on the availability of agricultural land for non-food production. Whereas more optimistic assumptions lead to a theoretical potential of 200-400 EJ/a or even higher, the most pessimistic scenario relies only on the use of organic waste and residues, providing a minimum of 40 EJ/a. More realistic assessments considering environmental constraints estimate a sustainable potential of 40 – 85 EJ/a by 2050. For comparison, current fossil energy use totals 388 EJ. In the short to medium term, projections expect biomass and waste to contribute 56 EJ/a in 2015 and 68 EJ/a in 2030. Global use of bioethanol and biodiesel will nearly double from 2005-2007 to 2017. Most of this increase will probably be due to biofuel use in the USA, the EU, Brazil and China. But other countries could also develop towards significant biofuel consumption, such as Indonesia, Australia,
Canada, Thailand and the Philippines.
Development of agricultural yields
Future development of global agricultural yields will determine the degree to which demand for food and non-food biomass can be supplied from existing cultivated land. Commodity prices are very likely to be significantly influenced by future yield developments. Although the overall development seems rather uncertain, various influences (such as water supply, climate change, environmental restrictions, the evolution of agricultural markets) make it rather unlikely that the growth rates of past decades will continue globally. A declining tendency in the yearly percentage of yield increases of major crops has been observed over the past decades. A higher potential for yield improvements is commonly seen for developing countries, and often especially for Africa. However, the FAO assumes future yield increases for cereals in developing countries which are closer to lower global average rates of recent years, i.e. around 1% per year. Plausible estimates from international institutions for global yields in the next decade are 1-1.1% p.a. for cereals, 1.3% p.a. for wheat and coarse grains, 1.3% p.a. for roots and tubers and 1.7% p.a. for oilseeds and vegetable oils. These rates of increase are significantly below average rates of the past four decades. Recent findings show that climate change has already reduced average crop yields. Future development may widen the gap between developed and developing countries, by decreasing production capacity in particular in semi-arid regions and increasing capacity in temperate zones. A higher frequency of extreme weather events will further increase uncertainty.
Development of food demand
In the past, agricultural yields grew faster than the world population. More food could be produced on existing cropland. In the future, the trends might become less favourable, as average crop yields may compensate for population growth but not for an increasing demand of animal based food. Between 2000 and 2030 the global population is expected to grow by 36% (medium projection of UN/FAO). This would be about the same rate that average crop yields are expected to increase. At the same time, however, food demand is changing towards a higher share of animal based diets, particularly in developing countries. The FAO expects the meat consumption of the world population to increase by ca. 22% per capita from 2000 to 2030, the milk & dairy consumption by 11% and that of vegetable oils by 45%. Commodities with lower land requirements like cereals, roots and tubers, and pulses will increase at lower rates per capita. As yield increases will probably not compensate for the growing and changing food demand, cropland will have to be expanded only to feed the world population. So far no explicit projection of global land use change induced by changing food demand seems to be available. From the Gallagher report 1, an estimated additional requirement of 144 to 334 Mha of global cropland for food in 2020 can be derived. Any further requirements, for instance for fuel crops, will be added on top of this.
Life-cycle-wide environmental impacts of biofuels The green house gas balances of biofuels
Life-cycle-assessments (LCA) of biofuels show a wide range of net greenhouse gas savings compared to fossil fuels. This mainly depends on the feedstock and conversion technology, but also on other factors, including methodological assumptions. For ethanol, the highest GHG savings are recorded for sugar cane (70% to more than 100%), whereas corn can save up to 60% but may also cause 5% more GHG emissions. The highest variations are observed for biodiesel from palm oil and soya. High savings of the former depend on high yields, those of the latter on credits of by-products. Negative GHG savings, i.e. increased emissions, may result in particular when production takes place on converted natural land and the associated mobilisation of carbon stocks is accounted for. High GHG savings are recorded from biogas derived from manure and ethanol derived from agricultural and forest residues, as well as for biodiesel from wood (BtL, based on experimental plants).
