Carbon Life Cycle Assessment Evidence Analysis: Review Report - Attributional Studies Extension

Abstract:

The ETI appointed North Energy Associates (NEA) to lead a new Carbon Life Cycle Assessment (LCA) Evidence Analysis project in its Bioenergy Programme. LCAs are used to understand the greenhouse gas emissions associated with bioenergy from across the supply chain, from feedstock production to energy production. Several different methodologies can be used in LCAs and this ETI project assessed the strengths and weaknesses associated with applying these methodologies to bioenergy value chains. It also reviewed sources of data for LCAs and produced a compendium of the best and most reliable data across different UK-relevant bioenergy feedstocks and value chains. This compendium has formed the basis of a series of carbon balance calculations across a range of bioenergy value chains so that emissions from different feedstocks can be compared.

The aims of this project on “Carbon Life Cycle Assessment Evidence Analysis” for the Energy Technologies Institute are to identify and review the existing evidence base, in terms of relevant life cycle assessments (LCAs) which calculate greenhouse gas (GHG) emissions associated with potentially major bioenergy value chains for the United Kingdom; to compile a compendium of the best and most reliable ranges of basic data used in such calculations; to develop suitable workbooks for consistent calculation of GHG emissions associated with these bioenergy value chains; and to produce results which can be compared and used to identify and prioritise key knowledge gaps.

This document is a supplementary report to the outcomes of deliverable ‘D2 – Bioenergy Life Cycle Assessment Review Report” from Work Package 2 of this project which has the main objectives of analysing previous relevant LCA studies by providing a critique of the robustness of the evidence base based on both data and methodologies used; a measure of certainty behind the data reviewed; and details of the confidence the reviewer may have in interpreting the data

• This report has been prepared in response to a specific request from the ETI; the additional full reviews of the 34 studies identified as adopting ALCA methodologiesis solely due to this request and not to any change in the original goal and scope that applies to all other aspects of the project.
• The 34 ALCA studies identified by the initial selection and screening process formed a sub-set of ALCA bioenergy studies likely to cover the scope of the project in terms of:biomass sources, being conventional forests (broadleaf, conifer and pine), plantation pine forests, short rotation forests (conifer and broadleaf),short rotation coppice (willow and poplar), miscanthus and wheat straw; geographical biomass provenance, being Canada, the USA and Europe; and specified conversion technologies.
• Due to the nature of the screening process, coverage of the value chains relevant to this project is less assured for the selected ALCA studies than for the CLCA studies in the main review; no supplementary screening was carried out to identify ALCA studies that would have been excluded from detailed review for a reason other than adoption of ALCA methodology (such as provenance of biomass).
• This report provides the results of each review as well as an assessment of the robustness of the evidence base provided by the studies (mainly in terms of coverage of value chains transparency of calculationsand methodologies adopted) and an examination of the differences and similarities between the studies.
• The mai nfindings from the review process were that, from the 34 reviewed ALCA studies, very few (11) of the potential (190) relevant whole bioenergy value chains were covered by 8 ALCA studies, and only 1 of these studies (a calculation tool with the potential to cover 3 of the specified value chains) had high transparency.
• Taking into account the analysis of the reviewed ALCA studies,which demonstrates the extensive variations in the methodologies adopted and the physical parameters used for results reporting, it is apparent that there are limits to findings on confidence and critical data that can be derived from them for the evidence base for the specified bioenergy value chains in this project.

Publication Year:

2017

Publisher:

ETI

DOI:

https://doi.org/10.5286/UKERC.EDC.000644

Author(s):

Rix, J.H.R., Evans, A.F.K., Elsayed, M., Hunter, A.J., Turley, D., Goldsworthy, M. and McNamee, P.