BIO-<strong>SNG</strong> FEASIBILITY STUDY – ESTABLISHMENT OF A REGIONAL PROJECTWith the ever rising need to secure future energy diversity and reduce greenhouse gas emissions it couldbe a considerable advantage if use could be made of the gas infrastructure and the expertise of theefficient industry that has developed around it by the use of synthetic natural gas (<strong>SNG</strong>), including <strong>SNG</strong>derived from renewable resources such as biomass – “<strong>Bio</strong>-<strong>SNG</strong>”.4.2 „PURE‟ BIOMASS RESOURCESIn coming to a view on the potential merit of <strong>Bio</strong>-<strong>SNG</strong> it is necessary to consider the magnitude ofbiomass resources in order to establish the scale of the benefits that might be realised in practice. Notethat this report does not address the potential of biogas derived from the digestion of organic matter inlandfills and anaerobic digesters but concentrates upon the thermochemical production of methane frombiomass types that are generally not digestible, i.e. woody biomass. Woody biomass can be classifiedaccording to its provenance; for example energy crops, agricultural and arboricultural residues, industrialco-products, and waste materials such as recovered wood.A certain amount of work has been accomplished to date on the quantities and prices of biomass fuelsthat could be obtained both from indigenous sources and on international markets 17 , and is collated inTable 4-1Fuel type Indigenous Import GlobalEnergy crops 60 -550 PJ/a
BIO-<strong>SNG</strong> FEASIBILITY STUDY – ESTABLISHMENT OF A REGIONAL PROJECTfor the solid biofuels remains a considerable challenge – each depending upon the other with investmentdecisions requiring certainty for both supplier and user.Estimates vary for indigenous production capacity for energy crops ranging from 60 PJ to 550PJ perannum depending upon the extent to which subsidies may be paid to growers to compensate for the lagbetween planting and harvest and sales 18 . It is interesting to note the implicit assumption that subsidiesfor energy crops are required to get the supply chain established rather than to compensate for theintrinsically higher cost base associated with energy crops pending the date when rising fuel prices couldbe expected to reach and overtake these. An investor in a plant using solid biofuel crops ought thereforeto satisfy itself that the cost of producing energy crops is not disadvantageously indexed to the prevailingcost of energy, or else gain satisfaction that support mechanisms would be sustained for a sufficientperiod of production and operation to assure commercial viability for both producer and user.WoodchipIn the UK, half of the commercial forestry is operated by the forestry commission, with the balance underprivate management. Approximately 9 million green tonnes are extracted per annum for timberproduction. Green timber is 50-55% moisture as harvested, although with seasoning can be reduced to30% naturally over time, without additional heat. This material can be utilised as woodchip, although itsuse is in direct competition with sawlog. Small roundwood is less valuable than sawlog, so woodchip canbe sourced from this material. Other than saw-wood, there is a variety of lower grade timber availablefrom forestry and the urban environment. In managing forestry, brash (removal of ancillary stems),thinning (trees which are too small for extraction) and poor quality final crops, can be extracted. Many ofthese are left on site, however, as the market for biomass fuels expands, these are a lower cost source oftimber. The arboricultural arisings in England, Scotland and Wales by Forest district, estimated to bec.670,000 19 oven dried tonnes per annum (12PJ pa). Similarly, in the urban environment and on road andrail-sides tree management gives rise to arboricultural arisings. These are usually chipped, and oftenlandfilled, but are increasingly being viewed as another energy biomass source.Internationally woody biomass has the potential to be sourced from highly forested countries such asCanada and Russia, with often distressed products being identified (such as beetle killed spruce). In theUK over 250PJ of international woody biomass resources have been slated for use in electricity projects.Whilst these resources are substantial, these commodities require extraction, haulage, shipping,unloading and delivery into plant, noting that the energy density of biomass is low relative to fossil fuels.As international jurisdictions develop renewable energy policies and seek to secure resources for theirenergy needs, international competition for these fuels will become more intense.18 DECC - <strong>Bio</strong>mass supply curves for the UK – E4Tech - March 200919Woodfuel Resource in Britain FES B/W3/00787/REP/2 DTI/Pub RN 03/1436 (2003)23
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