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Comparative Lifecycle Assessment of Anaerobic Digestion - AC0410

The project proposed here will deliver an LCA tool for use by DEFRA and other stakeholders to assess the environmental consequences of various anaerobic digestion (AD) and bioenergy options, from a comprehensive life cycle perspective that includes all upstream and land use change consequences. The tool will quantify environmental effects including climate change (GHG emissions), acidification (acidifying gas emissions), eutrophication (diffuse losses of N and P to water), and abiotic resource depletion (fossil energy and fertilizer consumption).
The project will involve the construction and assessment of scenarios for farm scale AD biogas production, bioethanol production from grass, wheat, maize and sugar beet, and biodiesel production from oil seed rape (Table 2 in section 2.3a), and compare these with two baseline reference farm systems: a large dairy unit in southwest England and a mixed arable farm in east England. In addition to LCA assessment for the aforementioned impact categories, pertinent ecosystem service impacts will be identified and reported for the main scenarios using a traffic light system. Economic assessment will also be performed, to the farm gate using the Farm-Adapt model (Bangor University), and post farm gate based on a lifecycle costing approach (literature values, industry consultation, expert judgement). Economic assessment will inform the development of realistic scenarios, and will be combined with lifecycle GHG abatement results to provide robust lifecycle GHG abatement costs.
Development of the LCA tool will involve the extraction and integration of outputs from relevant existing LCA models for conventional agricultural systems and bioenergy chains, and the extension of those models to fully cover the impact categories referred to. These models principally include the Bangor Livestock and Arable carbon footprint models and the European Joint Research Center’s life cycle inventory model for biofuels. Project partners proposed in this tender will bring expertise in environmental and economic assessment across the range of land uses and technology options involved. Partners from the German Johann Heinrich von Thünen Institut (vTI) will contribute expertise in LCA of bioenergy and AD systems and ecosystem service assessment, and will ensure that Germany’s extensive experience with farm scale AD is reflected in scenario and LCA parameterisation. Bangor University’s newly appointed Professor of Sustainable Land Use, David Chadwick, will also contribute to the development of pertinent scenario development, and complement Bangor University’s expertise in LCA.
The LCA tool and final report will express environmental effects per hectare of land, per kg food exported from the farm gate, and per MJ energy generated, and as a net change relative to baseline scenarios. Baseline scenarios will include relevant statistical averages where necessary for bioenergy comparisons (electricity generating mix, food waste disposal and animal manure pathways), and will be manipulable by LCA tool users to estimate changes relative to different baseline situations. The LCA tool will synthesise and combine key outputs from the contributory LCA models, in the form of modules and a user-interface displaying scenario combination options and results, but will not contain all calculations and functionality of those models.
The general aims of this proposed project are: (i) to provide robust lifecycle quantification of GHG reductions and other environmental effects (eutrophication, acidification, abiotic resource depletion) for a range of economically viable farm AD scenarios for a dairy and mixed arable farm, using comprehensive LCA; (ii) to provide a robust comparison of these environmental effects with those attributable to alternative bioenergy options, including biodiesel and bioethanol transport fuels, and miscanthus pellet heating or electricity generation; (iii) to quantify the farm and lifecycle economics of AD and alternative options in order to produce robust lifecycle GHG abatement costs. The intention is to provide a comprehensive assessment of AD and bioenergy options through application of a rigorous LCA approach that considers indirect effects including land use change. Economic optimization modeling and knowledge of German experience with AD will be applied to ensure that AD scenarios are realistic and parameterisation of the AD LCA is accurate.

A detailed work plan is provided in Table 1, Figure 1 and Figure 2 in section 2.3, below. Specific objectives (and delivery month within project timeframe) are:
1. To parameterise and expand existing carbon footprint models to generate baseline scenario LCA outputs for a large dairy farm in southwest England and a mixed arable farm in East England (Bangor University, month 2 delivery).
2. To identify likely scenarios of land use combinations on farms, and to compare farm economics across the different livestock and cropping scenarios (Bangor University, month 5 final delivery).
3. To parameterise and run existing LCA bioenergy models to generate scenarios LCA outputs for alternative bioenergy outputs, including indirect land use change (month 4 delivery). This will be led by vTI partners in Germany, but will include Bangor University to generate land use scenarios, including indirect effects.
4. To generate a specific AD LCA module, parameterised according to best available data from experience in the UK and Germany (month 4 delivery). This will be led by Bangor University, but will draw on German experience with AD via partners from vTI.
5. To compare ex-farm gate economics across the different bioenergy scenarios, and calculate lifecycle GHG mitigation costs (Bangor University, month 6 delivery).
6. To report on ecosystem service impacts across the various scenarios. This will be led by the vTI partner, but will involve consultation with Bangor University to ensure that the most relevant ecosystem service impacts and previous studies are considered (month 5 delivery).
7. To integrate LCA modules into a versatile LCA tool for assessing the main environmental effects of bioenergy GHG abatement options, and report on project results (Bangor University, month 6 delivery).

The above objectives are translated into discreet work packages in section 2.3b. Continuous feedback will be required between some of these work packages, and some work packages will rely on the completion of other work packages. These feedbacks are displayed in Fig. 1 in section 2.3a. Apart from the obvious dependence of the final model and reporting (WP 7) on the completion of all other work packages, notable dependencies are:
• Farm economics modeling (WP2) depends on feedback from baseline farm system definition (WP1) and will involve feedback with PGC scenario development (WP 3) and AD scenario development (WP4)
• Assessment of ex-farm gate bioenergy economics and mitigation cost (WP5) depends on feedback from all the preceding work packages
• Ecosystem service impact assessment (WP6) will rely on deliverables from baseline scenario definition (WP1) and dedicated bioenergy modeling (WP3)
• Farm system LCA model integration in WP7 will account for feedback from the AD module to the farm system module developed in WP1 and the PGC module developed in WP 3 by modeling the LCA effect of fertilizer substitution with digestate will depend on the quantity of imported AD feedstock.

Project Documents
• FRP - Final Report : AC0410 Final Report 05.12.2013   (3327k)
• ANX - Annex : AC0410 Annex 1 LCAD Methods   (658k)
• ANX - Annex : AC0410 Annex 2 AD & Biofuel module   (822k)
• ANX - Annex : AC0410 Annex 3 ES Assessment   (891k)
• ANX - Annex : AC0410 Annex 4 - LCAD user Guide   (327k)
• ANX - Annex : AC0410 Annex 5 Case Studies   (1217k)
• ANX - Annex : LCAD TOOL   (2047k)
Time-Scale and Cost
From: 2013

To: 2013

Cost: £69,637
Contractor / Funded Organisations
Bangor University
Climate Change              
Environmental Impacts              
Primary production