With EU targets demanding that by 2020 a significant amount of transport fuel should come from renewable sources, the focus is increasingly turning to second generation biofuels. Graham Rice and Adam Baddely look at how a new facility in England, set to produce bioethanol from household waste, compares to other processes.
In the past and during the days of 100% oil dependency, the idea that one day cars could be powered from fuel derived from society's waste would have seemed far-fetched. But this very idea is now becoming a reality.
Europe's first 'advanced or second generation (2G)' biofuel production plant, capable of converting household waste into bioethanol and renewable power, received planning consent in March 2010.
The development, designed to be built at Seal Sands in the North East of the UK, represents a major step for European biofuels production as it would enable further plants to be rolled out across the EU27 by 2020.
Such plants could provide enough sustainably produced bioethanol to contribute around 1% of the 10% renewable energy target in petrol by 2020.
Despite these benefits, however, the current EU and UK waste regulations restrict the use of biodegradable waste for advanced or lignocellulosic biofuel production, by favouring composting or anaerobic digestion, and the financial support to encourage such investment in Europe lags behind the USA and China.
Operated by bio-energy company, INEOS Bio, the process combines advanced bioethanol production, involving gasification, fermentation and distillation, with renewable power generation.
The bioethanol can be used as a renewable transport fuel, as is envisaged for the Seal Sands biorefinery, or as a chemical intermediate for the production of a variety of plastics and chemical materials.
The thermo-chemical gasification step provides feedstock flexibility, converting all types of biomass, including waste, into carbon monoxide and hydrogen gases.
The bio-chemical fermentation step is a highly selective and high yield synthesis of ethanol from these gases at low temperature and pressure.
Feedstock
A partial life-cycle assessment (LCA) of the process has been carried out by UK-based environmental consultancy, Eunomia Research and Consulting. The study compares the life cycle greenhouse gas emissions from the process with those from a range of alternative technologies when treating different waste feedstocks.
These include residual municipal solid waste (MSW), 'biowaste' (a mix of separately collected food and garden waste), garden waste alone and shredded wood waste. The analysis also considers two methods for the pre-treatment of MSW prior to its use as a feedstock for the INEOS Bio process - mechanical heat treatment (MHT) and mechanical biological treatment (MBT). The analysis was undertaken using two different methodologies:
1. Evaluation of the life-cycle GHG emissions reductions of biofuel produced from several key waste feedstocks using the INEOS Bio process under the Renewable Energy Directive (RED) methodology
2. Evaluation of the INEOS Bio process against alternative technologies for the treatment of different types of waste (the 'waste system' approach).
The analysis shows that all the bio-fuel systems result in emissions reductions that are in excess of 60% - the likely future minimum sustainability target for bio-fuel production stipulated in the RED. Results suggest that, when the fuel is produced from a purely organic waste feedstock (biowaste), the production and use of one litre of bio-fuel produced by the INEOS Bio process would result in an emissions saving of 3kg CO2 equivalent in comparison to the use of the same amount of fossil petrol. If residual MSW is collected, pre-treated to extract a biomass-rich fraction and used for biofuel production, the emissions savings would be slightly lower, at 2kg CO2 equivalent per litre of bio-fuel.
When using biowaste, garden and wood waste feedstocks, the emissions credit associated with electricity production is sufficient to offset all of the fossil emissions from the INEOS Bio production process and pre-treatment, delivering >100% GHG emission savings.
When treating MSW with the INEOS Bio process, offset emissions from recycling are included, along with offsets associated with the energy generation. This is such that avoided emissions are sufficient to offset all of the direct emissions from the process, giving an overall negative GHG balance. When treating biowaste, the INEOS Bio process outperforms both AD options as these convert relatively less carbon into transport fuel or electricity.
Sensitivity analysis was undertaken to consider the impact upon the results of improvements in recycling rates; improvements in the fuel pre-treatment process for the MSW feedstock; variation in the carbon intensity of electricity generation; and alternative treatment routes for the mixed plastic stream produced by the MSW pre-treatment processes. Variation of these elements did not have a significant impact on the results of the analysis.
In the UK, AD and composting are regarded by local authorities as preferential to the production of bio-fuels from waste for the purpose of meeting recycling targets and associated National Indicators (NIs). While there is provision in the revised Waste Framework Directive (WFD) through Article 4(2) to deviate from the Waste Hierarchy in order to deliver the best overall environmental outcome, there is no workable mechanism in place to enable this to happen in practice.
Defra is currently deliberating over this issue towards implementation of the EC revised WFD. Defra's most recent consultation document, however, indicates that this position is unlikely to change in the short-term.
Eunomia's study shows that, from a greenhouse gas emissions perspective, in the case of the INEOS Bio process, Defra's position on this issue cannot be justified. The central finding of the analysis is that under both of the assessment methodologies considered, technology configurations incorporating the INEOS Bio process result in far lower emissions of CO2 equivalent than all other alternatives.
The emerging renewable energy sector is vital to the economic recovery of the EU27 and to its energy independence. Bloomberg New Energy Finance reports that in the past five years, the US government has been very proactive in its support of the next-generation biofuels industry. Developers have responded positively to this government initiative, which has resulted in twice as many projects being on the drawing board as in the EU.
Similar to the wave of support to the oil industry following the 1960s North Sea discoveries, the government must now wake up and offer meaningful incentives for biofuels companies such as INEOS to support increasing production of this new 'green gold'.
Copyright © 2010: PennWell Corporation
