Energy from biomass: the size of the global resource

It identifies and discusses over 120 estimates for the future potential of energy from biomass  that have been published over the last 20 years. The assumptions – both technical and ethical – that lie behind these are examined and their influence on calculations of biomass potential described.
 
Note that the report concerns itself with biomass production in general, not with bioenergy.  In this report biomass potential refers to the amount of energy contained in the biomass. The term bio-energy potential is reserved for secondary energy carriers such as electricity after conversion losses have been taken into account.
 
The report does not seek to determine what an acceptable level of biomass production might be. What it does, rather, is show how estimates regarding different potential levels of biomass production vary depending upon our assumptions as to the following conditions (and the interactions between them):

• The global population
• Per capita food consumption and diet.
• Crop productivity increases
• The impacts of climate change on land, water availability and crop yields
• Water availability
• Decisions around nature conservation
• Rates of soil degradation and nutrient availability

The report argues that although biomass potential estimates have been criticised for not using standardised and consistent methodologies, in fact the range in estimates is driven more by the choice of these alternative assumptions than by methodological differences. It also points out that depending on the extent to which biomass production is implemented, the consequences for  global agriculture, forestry and land use; range from a negligible impact to a radical reconfiguration of current practice. The report also examines the insights the literature provides into the interactions between biomass production, conventional agriculture, land use, and forestry.
 
The report presents this very useful table.  It shows the range of estimates as to biomass’ potential  along the left hand side (low potential, medium potentials, high potential) and then looks at the conditions upon which these estimates are based.  For example, in a situation where diets are high in meat, or where agriculture is relatively low-input, and where there are constraints on the expansion of crop land, the potential for bomass production will be limited.  However, where increases in crop productivity are high,  the rate of population growth is at the lower end of the scale, and diets are relatively low in meat products (or there are high rates of deforestation), then the potential for biomass production is high.  Just as a reminder - the analysis is not based on what is or is not desirable, but rather on the conditions within which certain levels of biomass production are possible.

The report emphasises that seeking to predict future global food and biomass supply remains a highly speculative endeavour. There are uncertainties that cannot be resolved, and trade-offs that will always be contested, such as land-use choices and both positive and negative environmental impacts. It argues, however, that the evidence suggests that there is considerable potential to expand biomass before these more contested elements begin to dominate and that doing so could assist understanding of impacts and implications. Policy-making in an area beset by data gaps, scientific uncertainties and ethical debates is necessarily difficult. Moreover, policies related to diet, agriculture and land use are at least as important as those focused on bioenergy per se.
 
It makes the following policy recommendations

• A short run focus on tangible opportunities could expand biomass deployment while
• Addressing sustainability concerns. At a global level concentrating on how the first 100EJ could be made available sustainably would improve understanding of what is possible and the level of effort involved in going to higher levels of biomass use.
• Address key uncertainties through research and experimentation, for example in relation to suitability of so-called marginal and degraded lands, integration of food and biomass for energy systems, implications of energy crops on water use at regional level, and the environmental implications of land use change and related carbon flows.
• Develop environmental and land use regulation and sustainability standards that set biomass for energy, and agricultural systems, on a sustainable path.

 
ScienceDaily covers the report here.

Reference

Slade R, Saunders R, Gross R and Bauen A (2011). Energy from biomass: the size of the global resource. Imperial College Centre for Energy Policy and Technology and UK Energy Research Centre, London