From a representative sample of LCA studies on biofuels, less than one third presented results for acidification and eutrophication, and only a few for toxicity potential (either human toxicity or eco-toxicity, or both), summer smog, ozone depletion or abiotic resource depletion potential, and none on biodiversity. Increased eutrophication is a key characteristic of biofuels from energy crops when compared with fossil fuels. The life-cycle-wide emissions of nutrients depend critically on the application and losses of fertilizers during the agricultural production of biofuel feedstocks.

There is an obvious link between environmental impacts estimated by life-cycle impact assessments and water quality problems described at the regional scale. For instance, in the Mississippi drainage basin, increased corn acreage and fertilizer application rates, due to growing biofuel production, have been shown to increase nitrogen and phosphorus losses to streams, rivers, lakes and coastal waters, particularly in the Northern Gulf of Mexico and Atlantic coastal waters downstream of expanding production areas, leading to serious hypoxia problems.

These observations indicate that besides GHG emissions, other impacts of biofuels, such as eutrophication, are indeed relevant and already contribute to significantly worsened environmental quality in certain regions. Changing agricultural practices with the relevant feedstock crop may mitigate some of the pressure, but will most probably not be sufficient to improve regional environmental conditions, such as water quality. This also indicates a limitation of the product life-cycle assessment approach, which does not account for the spatial pattern of environmental impacts resulting from the combined effects of increased biomass production.

—“Assessing Biofuels”

Lifecycle GHG. The report finds that some first generation biofuels such as ethanol from sugar cane can have positive impacts in terms of greenhouse gas emissions. As currently practiced in a country such as Brazil, it can lead to emissions reductions of between 70% and well over 100% when substituted for gasoline.

However, the way in which biofuels are produced matters in determining whether they are leading to more or less greenhouse gas emissions. Life-cycle assessments (LCA) of biofuels show a wide range of net greenhouse gas savings compared to fossil fuels. While this mainly depends on the feedstock and conversion technology, other factors including methodological assumptions also have an impact.

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.

Production and use of biodiesel from palm oil on deforested peatlands in the tropics can lead to significant increases in greenhouse gas emissions—up to 2,000% or more when compared with fossil fuels. This is mainly as a result of carbon releases from the soils and land. However, a positive contribution to greenhouse gas emissions can arise if the palm oil or soya beans are instead grown on abandoned or degraded land.

Lifecycle impact of biofuels compared to fossil fuels for different environmental pressures. Source: “Assessing Biofuels”. Click to enlarge.

Increased emissions of GHG may result in particular when production takes place on converted natural land and the associated mobilization of carbon stocks is accounted for, the report finds. 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).

Methodological constraints. The wide variation in LCA results reflects the plurality of technologies studied, and is also to a considerable extent due to varying assumptions and methodological constraints, the report notes, such as uncertainty about nitrous oxide (N₂O) fluxes. Another constraint is the way land conversion related impacts are attributed. As one example, when oil palm plantations are established on converted natural forests and the associated emissions are depreciated over 100 years, GHG savings may result per hectare and year. Additional emissions will result if a depreciation period of 30 years is applied.

Improvement of the product chain oriented life-cycle approach seems necessary, and is ongoing, but basic deficiencies may only be overcome through the use of complementary analytical approaches which capture the overall impacts of biofuels in the spatial context.

—“Assessing Biofuels”

Suggestions. The report, Towards Sustainable Production and Use of Resources: Assessing Biofuels is based on a detailed review of published research up to mid-2009 as well as the input of independent experts world-wide. The report is designed to assist governments and industry in making sustainable choices in an area that over the past few years has become deeply divided while triggering sharply polarized views.

Biofuels are neither a panacea nor a pariah but like all technologies they represent both opportunities and challenges. Therefore a more sophisticated debate is urgently needed which is what this first report by the Panel is intended to provide. On one level, it is a debate about which energy crops to grow and where and also about the way different countries and biofuel companies promote and manage the production and conversion of plant materials for energy purposes-some clearly are climate friendly while others are highly questionable.

—Achim Steiner, UN Under-Secretary General and Executive Director of the UN Environment Programme

The focus of the report is on first generation biofuels; potential benefits and impacts of second and third generation biofuels (advanced biofuels) are partially included, and might be subject to a specific report at a later stage, according to the authors.

The report outlines a number of approaches for more for a more efficient and sustainable production and use of biomass.

The include increasing yields and optimizing agricultural production; restoring formerly degraded land; using biomass for power and heat rather than for liquid fuel; use of waste and production residues; cascading use of biomass (i.e., use biomass to produce a material and the recover the energy content of the resulting waste); and mineral-based solar energy systems.

The report also outlines key research needs in the areas of:

• Further exploring potentials and implications of biomass use
• Making better use of biomass
• Improving global land use
• Comparing and developing potentially more resource efficient alternatives.
• Improving methodologies ands safeguards.

Resources

• Towards Sustainable Production and Use of Resources: Assessing Biofuels