Advanced biofuel feedstocks – an assessment of sustainability
28 waste feedstocks – a comprehensive overview of what is sustainable, affordable, reliable, available – is this the most comprehensive survey ever?
In the UK, a comprehensive 28-feedstock assessment, commissioned by the UK Department for Transport from E4Tech, presents evidence on feedstock supply potentials and prices, the maturity and costs of different biofuel production options, direct GHG emissions of different chains, plus competing markets and indirect substitution effects for each feedstock. It also looks at recent policy developments and the effectiveness of multiple counting.
The study then proposes and applies a framework to facilitate the transparent assessment of feedstock sustainability and risks on a common basis, and determine which merit additional policy support.
Feedstocks include:
Bio-fraction of municipal solid waste
Bio-fraction of commercial & industrial waste
Straw
Animal manure
Sewage sludge
Palm oil mill effluent
Empty palm fruit bunches
Tall oil pitch
Crude Glycerine
Bagasse
Grape marcs
Wine Lees
Nut shells
Husks
Cobs
Bark, branches and leaves
Sawmill co-products
Black and brown liquor
Used Cooking Oil
Animal fats (Categories I and II)
Non-food cellulosic material
Short rotation coppice
Short rotation forestry
Small round-wood
Micro-algae
Macro-algae
Renewable non-bio liquids & gases
Waste carbon gases
Biofuel uptake within Europe has stalled in recent years due to the policy uncertainty surrounding Indirect Land Use Change (ILUC). Proposed changes to the Renewable Energy Directive (RED) have gone through rounds of Commission, Parliament and Council amendments since October 2012 – with ILUC factors, caps on food-based biofuels, multiple counting and sub-targets for advanced biofuels all under intense debate.
The 28 or so feedstocks within the Annex IX lists are proposed to count double (or quadruple) towards national renewable transport targets, and/or count towards a 2020 sub-target for biofuels from novel conversion technologies using these resources. This feedstock list started with the RED and the Commission’s communication on practical implementation, taking onboard criteria and classifications of wastes and resides drawn up by the Renewable Fuels Regulators Club in 2010. In their 2012 proposals, the Commission added feedstocks they considered to be low ILUC risk, but since then several other feedstocks have been added, removed or reinserted, but with no transparent rationale or underlying analysis. The process and criteria by which future feedstocks will be added to the list are also still unclear.
Sustainability of Annex IX feedstocks
In this study, we have collected information regarding the basic characteristics, supply potentials, technology compatibility, economics and sustainability for each of the 28 feedstocks within the Annex IX lists. The analysis is based on the best evidence publicly available that could be gathered within the short duration of the study, and we have highlighted where the available evidence is most uncertain and the additional information needs. For a more detailed picture, or a regional focus, market analyses for individual feedstocks will be required. Our synthesized findings are as follows:
1. Availability: Feedstock supply data for today and 2020 was collected (in million tonnes/yr and PJ/yr of biofuel equivalent) for the UK, EU and globally. MSW and C&I wastes, straw, manures, forestry and renewable electricity typically have the largest supply potentials. Other feedstocks have more modest potentials, whereas wine residues, tall oil pitch, crude glycerine resources are the most limited. Energy crops, short rotation forestry and algae will also be in short supply by 2020, but have longer-term potential.
2. Technology: There are numerous conversion technologies capable of transforming the Annex IX feedstocks into biofuel. Many routes are still at pilot scale, whilst those in demonstration, and hence potentially able to contribute meaningful biofuel volumes by 2020 include lignocellulosic ethanol and butanol, pyrolysis oil upgrading, gasification routes to alcohols, bio-Synthetic Natural Gas, Fischer-Tropsch diesel & jet, plus renewable electrolysis. Some technologies are commercially available, but are only compatible with a few of the Annex IX feedstocks, such as biomethane from anaerobic digestion (e.g. for MSW, C&I wastes), FAME biodiesel and Hydrotreated Vegetable Oil (e.g. for UCO, animal fats and micro-algae).
3. Economics: Wastes with a gate fee have a negative price, and those energy dense feedstocks (like tall oil pitch, crude glycerine, UCO and animal fats) have the highest positive prices – along with algae and renewable electricity. Delivered biofuel production costs have also been calculated in the study for 30 selected supply chains.
4. Competition: Competing uses vary widely, as do the likely substitute resources and price impacts if the Annex IX feedstock was to be diverted to biofuels. Generally, feedstocks that are disposed of (e.g. MSW, C&I wastes, UCO, waste carbon gases) or left uncollected (e.g.
straw, cobs, forest residues, small round-wood) can be collected sustainably up to certain limits. Manure and sludge spread to land can be treated via anaerobic digestion first before returning the digestate to land. Diverting a feedstock out of heat & power or industrial uses will have an impact through the carbon intensity of the replacement resource (i.e. high risks if replaced with fossil fuels vs. low risks if sustainable biomass used instead). Diverting straw and wood from animal bedding will likely rely on additional sustainable supplies of straw and wood to be found, whereas animal feed if diverted will need more roughage or carbohydrate crops produced from land (a potential ILUC risk). Some industries have minimal feedstock flexibility, such as the spirits industry (grape marcs and wine lees), paper & panel board (forestry) and high-value chemicals (e.g. glycerine). For those feedstocks specifically grown for biofuels, current competing uses are relatively unimportant, but the land they are grown on is important – in particular, energy crops grown on agricultural land could cause ILUC, if mitigation measures are not implemented. In general, those feedstocks with minimal expansion potential and high competition levels are likely to suffer price increases if diverted to biofuels.
GHG savings: Most Annex IX biofuel routes are able to achieve GHG savings above 80%. Routes using MSW, C&I waste, bagasse, wine lees, algae and waste carbon gases are more likely to fall into the 60-80% bracket, due to cultivation emissions, chemical or energy inputs, and transport distances. GHG emissions have been combined with the relative economics to give an indicative cost of GHG saving (in Åí/tCO2e) versus a fossil comparator.
Rationale for considering feedstocks for additional policy support
Based on the gathered information, the study developed a framework to determine feedstocks for which additional regulatory support could be justified (note that this does not specify the support mechanism). The following hierarchy of questions are illustrated as a flow diagram that can be followed to determine if a feedstock meets all the criteria to be eligible for support:
1. What is it classified as: a waste or processing residue (non-land using), or alternatively, an agricultural/forestry residue, co-product or product (land using)?
2. If land using, what type of land does it come from? Has the use of high biodiversity, high carbon stock or peat land been avoided? (meeting current RED is a minimum requirement)
3. What are the key competing uses, and potential substitute resources? Would diversion to biofuels result in a high risk of unacceptable carbon, cost, environmental or social impacts – such as the knock-on use of more fossil fuels or land? (These risks can be volume and location dependent). Alternatively, for new non-food crops, is there a risk of competition with food via ILUC?
4. Are the lifecycle GHG emissions savings of producing biofuel from the feedstock high enough (versus a suitable fossil comparator) to be supported? At least 60% will be required under the RED, but a higher threshold could be chosen by policymakers.
5. Would use of the feedstock for biofuels be economically viable without support, and hence likely to be deployed? Or would deployment only occur with support, due to the lack of commercial readiness of the conversion technology, infrastructure investments required or other reasons?
Applying these criteria across the whole of the Annex IX list leads to the following conclusions.
1. Several feedstocks have a significant uncollected resource that could be diverted from current disposal, produced without indirect impacts, or sustainably extracted with limited competition. MSW, C&I wastes, manures, forest residues, small round-wood, algae and renewable electrolysis are likely to need further support to be economically viable or help commercialize conversion technologies. UCO may not require additional support, depending on infrastructure investments to access domestic supplies.
2. Some feedstocks face higher levels of competition, and hence only a smaller unused fraction of the total supply is likely to be at low risk of causing indirect impacts. This includes straw, cobs, sewage sludge, bagasse, empty palm fruit bunches and waste carbon gases. For other feedstocks, such as animal fats, nut shells, husks, sawdust & cutter shavings, tall oil pitch, brown & black liquor, support should only be provided if the industries involved can show replacement of the missing energy demands with low carbon, sustainable alternatives – otherwise there is a risk of increased fossil fuel use offsetting any GHG savings.
3. Energy crops and short rotation forestry have longer-term potential (post 2020), but will require strict enforcement of ILUC mitigation measures to ensure the land grown on avoids food competition as well as being low risk (e.g. protecting carbon stocks).
4. A few feedstocks should probably not be supported for biofuel production, as they have multiple competing uses with high risks of detrimental indirect impacts – these include crude glycerine, grape marcs and wine lees. Until more information is available for Bacteria, the risks of its inclusion likely outweigh the benefits, as it could cover a broad range of processes (and feedstocks).
There is significant potential for biofuel production using low ILUC risk feedstocks, as many of the feedstocks in the Annex IX lists meet the criteria listed above – or could do so where only uncollected fractions are considered or when fossil fuel substitution can be avoided. However, most of the novel technologies that convert these feedstocks to biofuels still need to be commercialized, and only a few of the routes are currently economically competitive (compared to fossil transport fuels or conventional food-based biofuels) – despite the attractive GHG savings on offer.
Category: Top Stories
