Select Committee on Science and Technology Minutes of Evidence


Annex 1

Memorandum from the Biotechnology & Biological Sciences Research Council

  BBSRC's interests in developing sources of renewable energy are focused upon the exploitation of biological systems. Essentially, this currently means fundamental plant science research geared towards understanding the biology of biomass crops and their development for the efficient generation of electricity. Current examples of biomass crops under study are poplar trees, coppiced willow trees and elephant grass (Miscanthus).

  The following comments have been elicited from BBSRC's research community and are therefore focused on biomass energy crops. It is apparent that, at present, no bioenergy system can compete with fossil fuels in any market at any scale. With further research, however, this situation will change for the better.

1.  What are the cost-effective technologies available now for the generation of renewable energy, and those that are likely to become available in the next 10 years or so?

  The commercial exploitation of biomass for electricity generation is likely to become feasible within the next 10 years or so. Biomass fuels and residues can be converted to energy via thermal, biological and physical processes. Thermal processing currently attracts the most interest, of which gasification receives the most RD&D support as it offers higher efficiencies compared to combustion and fast pyrolysis is still at a relatively early stage of development. Both of these thermochemical conversion processes offer high conversion efficiencies, potentially competitive costs and considerable flexibility in scale of operation and range of products. Combustion, biological conversion processes (fermentation and digestion) and mechanical processing (eg vegetable oils) are well established and are commercially offered with performance guarantees.

  There are a few genetic markers already available in poplar and willow trees which identify traits that make a good biomass crop, though none as yet in the energy grasses. More of these markers will be identified as a better understanding is gained on what makes a good biomass crop, though the UK research effort is fairly modest at present. At Rothamsted Research (RRes), there are a number of interesting candidate traits which can be worked on very quickly with the necessary research support. The National Willow collection has been successfully transferred to RRes and there is a complete DNA fingerprint of all clones to ensure each is unique. This provides the basis for fundamental studies which will impact on biomass crop breeding and selection over the next 10 years. The genetic transformation of poplar is now established, though only limited work in this respect has been completed on willow. The challenges facing biotechnology in terms of biomass crops relate to improving the productivity and final energy density of the crop harvest, together with facilitating harvesting, processing, combustion and fermentation. There are a number of viable scientific options currently being tested, although many of them involve GM technologies. As with any crop, there are thermodynamic limits to yield set by total annual light interception and conversion. These limits can already be incorporated into economic models and used to estimate how significant breeding and management advances could be in the overall cycle of production. It is very important that these analyses are carried out as part of any strategy which seeks to generate viable biomass-based energy production systems.

  Further research is required on biomass crop pest and disease resistance, and also on economic management. The complete bioenergy system needs to be considered from biomass in the field or forest through to an energy product delivered to the consumer, rather than as discrete elements for research. Insufficient attention is currently paid to the interfaces between biomass production and its conversion.

2.  What is the number of sites potentially available for such technologies, and the obstacles to taking these up in terms of (a) planning and other consents, (b) manufacturing and installation capacity, and (c) providing the supporting infrastructure, such as access roads and extensions to the electricity network?

  Given the breadth of biomass crops under development—Miscanthus, Phalaris, poplar and willow, to name a few—and their differing growth requirements and harvesting times, there are few grassland or arable sites which could not support biomass energy crops. Work remains to be done on agronomy and farming system impact across all locations in the UK. For example, there may be some conflict with other non-agricultural or food uses of water in places such as East Anglia. The equipment for harvesting biomass crops is mostly available (though imported) and farmers would feel comfortable using it. The existing agricultural infrastructure for arable farming could be adapted fairly easily for biomass crops.

  Changes in farming subsidies under the Common Agricultural Policy would go a long way to persuading farmers to take up the cultivation of biomass energy crops. The necessary farm land would therefore become available. In a densely populated country like the UK with scarce land resources, it is important that the amount of useful energy delivered per hectare is optimised.

  Planning permission for power stations is problematic because of stack emissions and the environmental nuisance caused by traffic, though emissions from the combustion of biomass energy crops have been shown to be minimal. Local power stations with minimal transport distances remain crucial to the successful commercial exploitation of biomass crops in electricity generation. All the current biomass products have dry-matter heat contents of around 50 per cent of that of coal, therefore stations will require large storage facilities.

  Technical barriers to electricity production from biomass crops remain, but are generally soluble in the medium term. Non-technical barriers (logistical problems) are poorly appreciated and often more significant than expected.

  It is important to appreciate that biomass is a diffuse resource, arising over very large areas and thus requiring large land areas with substantial logistical problems in collection and transport as well as high costs. Typically a sustainable crop of 10 dry t/ha/y of woody biomass can be produced in Northern Europe rising to perhaps 15 or maybe 20 dry t/ha/y for energy crops in Southern Europe. Thus an area of 1 sq km or 100 ha will produce 1,000 dry t/y enough for a power output 150 kWe at low conversion efficiencies or 300 kWe at high conversion efficiencies. It is therefore difficult to visualise power generation plants much bigger than around 30-40 MWe anywhere in Europe and even these will require a planted area of around 100 sq km. A further complication with almost all forms of biomass is their seasonality—forestry and coppiced crops can only be harvested during the winter months and energy crops and agricultural residues are even more seasonal, typically only being produced for a few months a year. Extensive storage provision thus has to be made. One solution to this problem is a multi-fuel system and increasing efforts are underway to develop such processes that can accept a number of different fuels either mixed or separately. The current view is that even these plant sizes are limited in number with a more typical plant size of 5-15 MWe likely to dominate the market in the short term. However, in locations with extensive forest products industrial operations it is technically feasible and economically attractive to have large scale bioenergy Combined Heat and Power (CHP) plants where the process residues are utilised as fuel for the energy requirements of the local industry. For example the Alhomens boiler in Finland (commissioned in 2001) has a design capacity of 500 MWth and is designed to operate up to 100 per cent biomass or mixtures of biomass and peat. Biomass and agricultural wastes are very similar in their arisings, with most European industries individually producing comparable quantities of material, although overall regional and national totals may be substantial.

3.  What are the logistics of providing stand-by capacity for times when intermittent sources are not available?

  For biomass crops, this relies on being able to co-fire a range of energy crop species which can be harvested at different times throughout the year. Co-firing of willow/poplar and grasses has been developed. The drying of wood (and especially grasses) for medium to long-term storage is a problem given power consumption, though it is possible and just economic.

4.  What are the intermediate milestones that should be set on the way to achieving the White Paper's aims?

  A realistic milestone for the contribution of biomass energy crops to the total renewables target would be 15 per cent by 2020. To achieve this would require some additional research investment and incentives to farmers above the

45 per hectare (on set-aside) currently being discussed at the European Commission. It is important that targets should be set to reflect the potential contribution of biomass crops to energy production in different portions of the country. These should emphasise local production and utilisation, and should be complemented by targets for larger, more centralised electricity generation from biomass crops.



 
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