The UK Renewable Energy Strategy commits to an increased and sustainable supply and use of biomass for heat, power and transport. The aim is to boost the bioenergy sector by bringing more woods back into management; incentivising energy crops and researching new ones as well as making better use of biomass waste.
Why is Anaerobic Digestion (AD) such a big bioenergy opportunity?
Anaerobic Digestion is considered to be one of the more significant conversion technologies capable of deriving energy from a variety of bio-waste materials and creating a demand for the supply of AD plant, equipment and facilities varying from farm based installations to municipal scale installations. AD is a mature technology outside the UK, and Germany has been utilising AD for energy production purposes for 20 years, currently operating 400 Municipal scale installations and 3,000 farm scale installations. In the UK, AD is an established technology in the waste water treatment sector, but presently there are no more than 60-70 AD biomass installations of varying scale with possibly more in the planning process.
The UK potential for biomass AD is evident from the availability of the estimated 12 million tonnes per year of organic municipal solid waste biomass feedstock with a calorific value of 65% of natural gas with an energy potential of 4.6TWh per year. If the gas was used to fuel gas engines for electricity production at 40% conversion efficiency, there is a potential market for a large number of 1MW sized plants based on the bio-waste element from municipal solid waste. AD installations can be configured to meet bespoke needs from small scale to industrial scale with technologies, mechanical systems and built environments integrated to process the type and scale of biomass feedstock available and to achieve the desired energy outputs. Table 1 indicates the range of market opportunities available in terms of the number of installations and the potential CAPEX value spend to deploy these installations.
Note: No quotes above are maximum – i.e. in the case of energy Crops it is either 500,000 25kW systems or 125,000 100kW systems or a combination of the scales indicated.
Key market opportunities
Sources:
Agricultural ‘Energy crops’: the UK government estimate that 1 million hectares of land is currently unsuitable for food crops and could be used to grow crops for bio-energy. Eight million tonnes could produce 27TWh of energy.
Waste Wood: The UK produces 5.4 million tonnes of waste per year consisting of wood chip/pellets and short rotation coppice. The estimated combined total energy output from waste wood would be 27TWh.
Biowaste: The UK Waste and Emissions Trading Act 2003 are keen to divert waste organic materials from landfill disposal. The UK government are confident that 33% of the 36.12M tonnes of Municipal Solid Waste generated in the UK each year is organic and suitable as a biomass feedstock.
Process:
Anaerobic digestion: Equipment and facilities vary from farm based installations to municipal scale installations. Germany has been utilising AD to extract energy from bio-waste for 20 years and has 3,000 farm scale installations. At present the UK has no more than 50 AD biomass installations. The UK potential for biomass AD is evident from the 12 million tonnes of organic municipal waste with a calorific value of 65% of gas and an energy potential of 4.6TWh pa. The integrated AD process is illustrated in figure 1. AD installations can be configured to meet needs from small scale to industrial scale to achieve the desired energy outputs. Bio-energy is derived by converting organic materials (biomass) into heat, energy or fuel using conversion technologies like Anaerobic Digestion or gasification to extract usable gas; combustion stoves and boilers to provide heat; chemical processes such as Transesterification to produce liquid fuels; or processes such as Pyrolysis to produce liquid fuels, solid fuels and gas.
Figure 1: Integrated process of AD and materials and machinery involved.
Supply chain opportunities
The supply chain is diverse with opportunities outlined in table 2:
The scale of bio-energy related business opportunities ranges from domestic applications such as wood fired boilers to multi-million pound waste-to-energy. Figure 2 highlights the key opportunities available in AD. Figure 3 illustrates the services, equipment and supplies necessary for AD (click on images for a bigger picture).
Figure 2: Review of the five key supply chains.
Figure 3: Review of the equipment, services and supplies required in Bio-energy processes.
AD – Is it sustainable?
The key economic, social and environmental factors that make AD a sustainable process are highlighted in table 3.
Drivers and incentives
AD is eligible for Feed-in-Tariffs (FITs) which are designed to encourage small scale low carbon generation by non-professionals. FITs support new AD schemes up to a maximum of 5MW with tariff rates varying with scale. Table 4 provides information on the current tariff which will be fixed for 20 years. The generation tariff is dependent on the scale of the technology but payment is for every kWh generated and metered by the generator. The export tariff is a guaranteed amount that generators are eligible for. For more information on the terms and conditions of the FIT scheme see www.fitariffs.co.uk.
Table 4: The generation and export tariff in 2010 for AD (Export tariff is currently 3p/kWh)
Renewable Heat Incentives will be available from 2011 which is a scheme that involves payment for renewable heat according to generation (kWh).
