FP6 - 502824
CROPGEN - Renewable energy from crops and agrowastes

Contacts
Website: www.cropgen.soton.ac.uk/
Summary Information

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Biological Conversion : Biotechnology : Crops for Liquid Biofuels and Biogas : Liquid Biofuels and Biogas : Sustainable Development and Renewable Energy

Contract No:	SES6-CT-2004-502824
Source:	Project Presentation

Source:	Project Presentation - pdf

Project Presentation

Objectives

The overall objective is to produce from biomass a sustainable fuel source that can be integrated into the existing energy infrastructure in the medium term, and in the longer term wilt also provide a safe and economical means of supplying the needs of a developing hydrogen fuel economy. The concept is based on the use of anaerobic digestion (AD) as a means of producing methane from biomass, including energy crops and agricultural residues. The technology of biochemical methane generation is well established; the breakthrough to a cost-effective and competitive energy supply will come from engineering and technical improvements to increase conversion efficiencies, and from reductions in the cost of biomass by the introduction of integrated systems making use of novel and multi-use crops and agro-wastes. The research will determine how the technology can best be applied to provide a versatile, low-cost, carbon-neutral biofuel in an environmentally sound and sustainable agricultural framework.

The main aims are to

To identify novel process designs that will help overcome known problems of bio-digester stability when dealing with high cellulose content bio-energy feedstocks.
To develop methods for retention of feedstock solids and to advance the design of robust technology allowing phase separation and uncoupling in AD.
To quantify the usage and potential savings in the use of different mixing systems and reactor configurations.
To look at processing control strategies using decision support systems, neural networks and fuzzy logic to maximise biogas production
To compare methods for characterisation of plant materials for their bio-energy potential.
To describe the batch growth kinetics of methanogenic activity and to relate them to the primary composition of plant material.
To determine rates of degradation and ultimate methane yield of selected plant materials.
To determine accurate energy balances for selected crop species by calorimetric methods.
To predict biogas energy production per hectare of arable land under different conditions.
To classify and rank crop species that can be grown for bio-energy production.
To select optimum storage practices and to evaluate the potential of pre-treatments for maximising bio-energy production from crops.
To assess advantages and limitations of co-digestion of energy crops with animal slurries.
To assess the characteristics of digested residue and their potential benefit in the agro-ecosystem.
To quantify benefits from energy crops with a dual or multiple function, eg. increasing soil fertility by nitrogen fixation, producing high protein seed products hr animal feed or providing a nutrient-balanced soil conditioner from energy-depleted resides.
To maximise net overall energy surpluses from digestion and to assess the potential for optimising energy provision in an integrated livestock/arable environment.

To evaluate possible market, educational and legislative barriers to crop-based bio-energy use both nationally and EU wide and analyse methods to overcome the barriers.

Specific targets

Parameter	Target
Digester volatile solids loading rates for pilot-scale plant per unit of reactor capacity	10 kg VS m^-3
Digester volatile solids loading rates in innovative lab-scale two-phase systems, per unit of reactor capacity	20 kg VS m^-3
Biochemical methane potential of crops identified in research as suitable for energy production	0.35m³ kg¹
Net crop energy yield after inputs into cultivation and harvesting	48%
Life cycle cost for conversion of biomass energy into methane	35 euro per MJ
Full life cycle cost of energy production in the form ofelectricity	0.035 euro per kWh
Full life cycle cost of energy production in the form of biofuel	0.036 euro per kWh

Key issues

Annual growth plant tissue with its high water content is inherently unsuitable for combustion or other thermal treatments: the ideal route for such materials is through biochemical conversion. The concept of an energy-only farm, where annual crops are grown solely for biomethanisation, is still speculative and depends on two key factors: the development of digesters with higher conversion efficiencies than current conventional reactors: and the optimisation of other costs and benefits. These problems could be solved in the medium term. The concept of energy self-sufficient farming units can be realised in the short term by introduction of integrated systems making effective use of bio-residues in energy production. This, coupled with selection of crop species with multipurpose use as soil improvers and fodder crops, could yield a positive energy balance allowing export of energy off the farm.

Technical approach

The work will identify crops and agro-wastes best fined to energy production in an integrated farming environment, consider energy losses in production and processing, and use these to set net energy production targets. The role of storage and pre-treatments will be considered. Co-digestion will be evaluated for improving energy yields. Some agricultural residues will be investigated as potential high-yield substrates. Innovative bioreactor designs and operating modes will be tested. A database of bio-kinetics for use in design and operation will be established. True lift-cycle costs for biogas production will be determined in large-scale trials for verification of laboratory data and predictive models The work will consider the need for continuity of energy supply in a farm environment. Issues of sustainability, environmental impact and socio-economic factors will also he addressed.

Expected achievements/impact

The results will add to EU databases on bio-energy crops; give engineers the necessary tools to develop the technology: and provide the farming community with evidence of profitable energy production without subsidy and within the Eli's target cost for renewable energy. The work will contribute to security and diversification of energy supply, reduction in greenhouse gas emissions, soil amelioration and reduced water pollution. It will also create opportunities for increased employment in agriculture and reinforced competitiveness in technology export