How can Life Cycle Assessment inform bioenergy choices?

Published: 19 July 2018


Analysis by the Energy Technologies Institute (ETI) and others indicates that increasing the sustainable production of biomass resources and the use of bioenergy for energy generation can play an important part in meeting the UK’s 2050 greenhouse gas (GHG) emissions reduction target.

However, the type, quantity and geographical source of additional biomass feedstock, and how this feedstock is used, will have an impact on the extent to which bioenergy delivers GHG emissions savings at a global level.

Delivered by Energy Systems Catapult, this Perspective report follows completion of an ETI project, Carbon Life Cycle Assessment Evidence Analysis, and introduces the way Life Cycle Assessments (LCA) have been used to quantify the impacts of producing bioenergy, along with highlighting some of the key things to consider when defining the scope of a bioenergy LCA or interpreting the results of bioenergy LCA studies.

Key points

  • LCA is a well-established technique for quantifying the greenhouse gas (GHG) emissions (or other environmental impacts) associated with a product or system. However, its outputs can only be properly interpreted if its scope, methodological approach, assumptions and data have been clearly defined and communicated. This is necessary to establish whether LCAs are comparable, and to identify the source of any differences in results
  • LCAs which report the emissions directly associated with existing bioenergy systems, such as those from transport and pelleting, are an important part of sustainability compliance, but they do not provide an insight into the whole system impacts of increasing bioenergy production. This requires a different LCA approach, taking into account the indirect impacts a change in bioenergy production could have, for example, on forest carbon stocks. Therefore logically, implementing bioenergy sustainability criteria which deliver GHG reductions at a whole system level, requires more than monitoring of direct emissions. Additional measures are needed to encourage good land and forest management practices and prohibit high-risk practices, not only in relation to bioenergy feedstocks but all bio-based products.
  • Given that the global challenge is to restrain total emissions of greenhouse gases over time to less than a fixed total, the aim of biomass production and bioenergy use should be to help deliver a global system (including energy and land use) that produces the lowest emissions overall. When other factors are taken into consideration, this way of producing biomass and bioenergy may not be the optimum system but it should be the reference case against which other options are compared to find the best use of land and resources.
  • Where uncertainty, because of empirical knowledge gaps or lack of understanding of the bioenergy system, results in a wide range of possible results from an LCA, this is a prompt for developing further evidence. Progress has been made in reducing these knowledge gaps but priority areas for further research include mapping the impact of producing bioenergy feedstocks on wider farming or forest systems in geographical areas where this is not well understood. There are also empirical data gaps, particularly relating to the emissions resulting from biomass storage, where further research could improve best practice guidelines.
  • Where there is a tension between different ecosystem services, it is important for sustainability criteria to consider the value of GHG savings from bioenergy together with the value of the additional ecosystems services forests and other land types can provide, such as biodiversity, regulation of air, soil and water quality, and cultural value. Given the potential to increase or reduce these at the same time as increasing biomass production, a regional strategy for forest and land management is necessary to ensure that ecosystems services are at least maintained, if not increased, on average, across the region under consideration.