Marketing Study for Biomass Treatment Technology Technical Appendix 3, NNFCC project 10/003, November 09

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3 Contents 1.0 Introduction Markets for Fractionation Products Sugar Markets Hemicellulose-derived Sugars Pulp Markets Lignin Markets Industrial Use Domestic Markets Viability of the NREL Clean Fractionation Process Modelling on 2000 Data Effect of Improved Solvent Recycling and Recovery Modelling on 2007 Data

4 Figures Figure 1 - World Sugar Prices Figure 2 - World Sugar Prices (3)... 6 Figure 3 - NBSK Pulp Price Europe ( )... 8 Figure 4 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation process given a daily throughput of 2,000 tonnes or 500 tonnes of corn stover per day Figure 5 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation process given a daily throughput of 2,000 tonnes or 500 tonnes of corn stover per day and given improvements to the process parameters. 16 Figure 6 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation, as for Figure 5 but using a base year of Tables Table 1 - Price of Lignin Compared to Other Industrial Energy Sources... 9 Table 2 Price per Tonne, Calorific Value and Price per MWh for Commonly Available Biomass Energy Sources in the UK

5 1.0 Introduction The renewables sector encompasses all renewable fuels, energy and materials. Renewable fuel and energy are high volume sectors, requiring significant scale of production on a national or international level to be economic. The renewable materials sectors are generally smaller and offer more local or regional opportunities, producing crops, products and materials on a smaller scale, often with lower investment needs. This Appendix investigates the prices at which biomass fractionation products could be sold at and the economics of a typical biomass fractionation process. This can be used as a benchmark assessment of the most viable products for fractionation given the inherent costs associated with the process. 4

6 Aug-99 Mar-00 Oct-00 May-01 Dec-01 Jul-02 Feb-03 Sep-03 Apr-04 Nov-04 Jun-05 Jan-06 Aug-06 Mar-07 Oct-07 May-08 Dec-08 Jul-09 Worls Sugar Price ( /t) Marketing Study for Biomass Treatment Technology Technical Appendix 3, NNFCC project 10/003, November Markets for Fractionation Products This section investigates the price which could be charged for fractionation products and how this impacts on the viability of the fractionation process. In all cases, historical price data in currencies other than Sterling has been converted to Sterling based on the exchange rate at that time, using the historical currency exchange calculator at (1). 2.1 Sugar Markets Cellulose and hemicelluloses can be deconstructed through two main routes, namely acid hydrolysis or enzymatic hydrolysis. The resulting sugars can be used to produce a wide range of valuable products. Methods to convert sugars to chemicals include fermentation (such as ethanol, butanol or other platform chemicals), thermal or chemical treatment (such as furfural). Methods for the conversion of glucose are better developed than for other sugars, and as such the section below principally refers to glucose derived from degradation of cellulose and hemicelluloses 1. Sugars can be produced from a number of crops including sugarcane and beet or from lignocellulosic materials. The majority of sugar in world commerce is sucrose 2, currently derived from either sugar cane (~70%) or sugar beet (~30%). Sugar is traded on international markets in the raw or refined state; refined sugar is traded at a premium over raw sugars. Once derivatised to sugars, there is no fundamental advantage of using one biomass type over another aside from certain sustainability concerns. Therefore, sugars derived from sugar cane are equally as useful for chemical building as those from wood or grasses, and thus these sugars (and the products derived therefrom) would need to be competitive with those derived from these feedstocks Figure 1 - World Sugar Prices Source: (2) 1 But note that in the longer term, as discussed in Section 2.2, sugars derived from hemicelluloses may reach world sugar prices depending upon market demand and specific end uses. 2 Sucrose is a disaccharide sugar made up of glucose and fructose. 5

7 02-03 to 07 to to to to to to to to to to to 18 Price (US $/t) Marketing Study for Biomass Treatment Technology Technical Appendix 3, NNFCC project 10/003, November 09 Sugar (as sucrose), as for other commodity prices, shows volatility over time as a result of differential supply and demand, and annual variations in global production. Indeed the world (raw) sugar price in the past 10 years has varied from around 73 /tonne to 239 /tonne as shown in Figure 1. In general, sugar prices for 2017/2018 are estimated to be around $375 / tonne ( 225 / tonne 3 ) for refined sugar, and to around $300 / tonne ( 180 / tonne 4 ) for raw sugars as shown in Figure 2 below. Given the inherent volatility of the sugar markets, the certainty of these prices being achieved is unclear Raw USD/t Refined USD/t Figure 2 - World Sugar Prices (3) Little sugar is traded on free markets. Sugar prices have historically been significantly influenced by the impact of trade agreements and trade subsidies. Thus, the US internal market price for sugar (traded under the No 14 market) has historically traded at a 2-3 x premium over the world sugar price (traded under the No 11 market). Similarly, the EU CAP (see Technical Appendix 1 for further details) has historically resulted in the over production of sugar from sugar beet in the EU. In the case of both the EU and USA, higher prices for domestic sugar were achieved by effectively reducing the import of sugar from poorer countries. The EU sugar regime ( ) is designed to reduce sugar support prices, reduce EU sugar production and exports, reduce import quotas and limit re-export in sugars. EU sugar support prices are to be cut by 36% over 4 years alongside a voluntary restructuring scheme which is aimed at reducing production by around 6 million tonnes in the same period (4). However, it is important to note that the EU sugar regime is limited to food uses for sugars. In general, in order to increase profits, manufacturers will choose to develop their industry in the region which has the lowest cultivation and raw material processing costs. In this regard, sugar cane has the lowest cost fermentable sugars and Brazil has the most developed infrastructure for the cultivation and processing of sugar cane as a result of its historical associations with the bioethanol industry. The 3 Based on current exchange rate between $ and (August 2009) 4 ibid 6

8 Brazilian sugar industry, especially with the focus on removing trade barriers in EU markets, provides the benchmark by which all other sugars for industrial purposes will be compared. 2.2 Hemicellulose-derived Sugars With the exception of glucose, hemicellulose derived sugars are currently traded as speciality chemicals, for niche applications. As the biorefinery concept takes off, it is likely that there will be an increasing bulk market trade in sugars derived from hemicelluloses. As they are not traded on bulk chemical markets, we have had to derive a value for the sugars derived from hemicelluloses based on their value for fermentation relative to world sugar markets (as fermentation is one of the most likely end use markets given the research in this area at least in the short term). The efficient fermentation of xylose and arabinose to ethanol, without the formation of xylitol and arabinitol has been a goal of researchers aiming to maximise the yield of ethanol from lignocellulosic materials. Reported efficiencies of the conversion of hemicelluloses sugars to ethanol are around 37% (5). This compares to the conversion efficiency of glucose to ethanol of around 46% (5) and the theoretical yield of ethanol of 51% (6). The efficiency of converting hemicelluloses to ethanol is therefore 79% that of glucose sugars and we could assume that their value to an ethanol producer will be proportionate. The average world sugar price for 2000 was 122; so using this methodology, this suggests that hemicelluloses would be around 96 /tonne. In comparison, the 2000 scenario by Jechura (7), hemicelluloses were costed at 5.6 cents per lb, equivalent to /tonne. Based on an average world sugar price of 109/ tonne in 2007, this suggests that hemicelluloses would be worth around 86 / tonne in While it is unlikely at present that sugars derived from hemicelluloses will be sold at world sugar prices, this remains a longer term opportunity if there is sufficient margin available between the cost of processing and isolation and the world sugar price. Industrial biotechnology is a fast moving field and the commercialisation of microbes for sugars derived from hemicelluloses (including C6 sugars and C5 sugars) is rapidly approaching, especially for fuel ethanol. Technologies developed for the biofuels sector will be leveraged to the chemical industry (8). 2.3 Pulp Markets Biomass fractionation is reported to give high purity cellulose, which, especially with the addition of a bleaching step, is similar to high purity cellulose derived from pulping markets known as dissolving pulp (9). Thus, assuming the correct quality can be achieved, it could be sold for a similar price. Many pulp products are commodities which can show considerable price volatility with time according to supply and demand. Figure 3 below shows the variation in price of Northern Bleached Softwood Kraft (NBSK) pulp in Europe between 2001 and As a highly specialised product not traded on bulk markets, prices for dissolving pulp are less readily available, although they are known to be traded at a premium over NBSK (usually between 100 to 300) as a result of the increased costs involved in making a higher purity product. 7

9 J'01 M S J'02 M S J'03 M S J'04 M S J`05 M S J`06 M S J`07 M S J`08 M S J`09 M Pulp Price ( /t) Marketing Study for Biomass Treatment Technology Technical Appendix 3, NNFCC project 10/003, November Figure 3 - NBSK Pulp Price Europe ( ) In common with many other commodities, dissolving pulp has undergone significant fluctuations in price in the past year. Paperloop Inc (10) reported that there was an increase in dissolving pulp from $800 ( ) tonne in January 2007 to $1,100 ( ) to $1,300 ( ) per tonne in September 2007, an increase of 62.5%. RSI reported that dissolving pulp prices decreased more than 30% in Asian markets in early 2009 year due to weakening demand for rayon staple fibre and suggested that prices may face further downward pressure because of a wave of new viscose pulp capacity now starting up in South Africa, Brazil and Canada (11). 8

10 2.4 Lignin Markets Lignin isolated from a fractionation process could be used for the production of chemicals or combusted, either on site or sold to external markets. There is no commodity market in lignin thus it is difficult to elucidate a price at which it could be traded. Given that the most near market application of lignin is in combustion, where it could be used to generate electricity and/or heat or for distribution, we can use the price of lignin for energy as a benchmark, albeit low value use. The moisture content of lignin recovered from the NREL Clean Fractionation process was reported to be 7.4% by weight (7), but in the following calculations, we have used a conservative estimate of 10% moisture content in the recovered lignin Industrial Use The use of any biomass for energy generation in the UK is incentivised under the ROC scheme (discussed in Technical Appendix 1). The introduction of the Renewable Heat Incentive (due to be introduced in April 2011) to reward the utilisation of heat derived from renewable sources could further increase the attractiveness of burning biomass (and therefore also lignin) although at the time of writing this report, the proposed level of reward under the RHI is unknown. Lignin could be either used at the fractionation facility in order to power the process (and gain ROC rewards) or sold to external energy markets (both industrial and small scale commercial and domestic). Table 1 below examines the cost competitiveness of lignin as an energy source compared to coal, oil and natural gas, common energy sources for industrial applications. Table 1 - Price of Lignin Compared to Other Industrial Energy Sources Price per tonne Pence per kwh /MWh /GJ Price (per tonne) at which lignin could be charged at on an equivalent GJ basis Coal Low High Oil Low High Natural Gas Low High To be cost competitive with coal, oil and natural gas as a fuel source for large industrial processes, the cost of lignin would need to vary from 22.5 to 63 per tonne for coal, 30 to 167 per tonne for oil and 39 to 101 per tonne for natural gas. Lignin has the potential to be used as an energy source in these markets, especially if ROCs make it even more attractive to use biomass. 9

11 2.4.2 Domestic Markets Table 2 below shows selected domestic energy sources in terms of price, calorific value and the price per MWh of energy supplied. Table 2 Price per Tonne, Calorific Value and Price per MWh for Commonly Available Biomass Energy Sources in the UK. Fuel Price per tonne ( ) Calorific Value (GJ/t) per MWh /GJ Price (per tonne) at which lignin could be charged at on an equivalent GJ basis Wood Chip (30% moisture content) Wood Pellets ( % moisture content) 5 Natural Gas Heating Oil LPG (bulk) As a biomass source, lignin would be potentially fed into the same markets as wood chips and wood pellets owing to the similar infrastructure requirements needed for utilisation of these fuels. To be competitive with wood chips on an energy basis, lignin could be sold at 146 per tonne, and to be competitive with wood pellets on an equivalent energy basis, lignin could be sold at 267 per tonne. Whilst lignin isolated from kraft pulp mills may be high in sulphur and thus limited to industrial applications where sulphur capture capability could be added, lignin derived from fractionation and pre-treatments is sulphur free and could be used in domestic markets. Based on this, lignin derived from fractionation could have applications as a high quality, high energy biomass source for domestic markets. However, given that the majority of biomass boilers in the UK have been designed for wood materials, pellets would need testing in existing domestic biomass boilers to ensure that there were no detrimental effects from lignin combustion. Given the increasing emphasis on quality standards for biomass fuels, especially at the domestic scale, the potential for lignin based pellets to conform to these standards would need investigation. There are around 1.5 million households in the UK which utilise oil for heating purposes, primarily in areas off the gas grid, with particular clusters in rural areas, especially in the South West of England, Wales and Northern Ireland (12). The annual market for oil for domestic heating was around 3 billion litres (or 3,000 m 3 6 ) in 2007 (12). Given an energy density of t /m 3 this gives an equivalent tonnage of 2, Assuming a lower heating value of 42.5 GJ/t, this would equate to an energy use of 104,167.5 GJ each year 8. Lignin has a lower heating value of Biomass Energy Centre 6 As there are 1,000 litres in every cubic metre billion litres. 7 Kerosene (used as heating oil in the UK) has a lower heating value of 42.5 GJ/t and a specific density of kg/m 3. 8 A similar figure can be reached if we assume that there are 1,244 litres of kerosene in a tonne. This gives an annual tonnage of 2, tonnes per year. 10

12 GJ/t therefore, if all of the UK market for domestic heating oil was replaced by lignin, this could provide a market for 4,101 tonnes of lignin pellets each year. There is also the possibility of using lignin as a partial or full substitute for wood pellets. It was estimated that in 2008, approximately 539,000 oven dry tonnes of wood pellets was supplied in the UK. Wood pellets have an energy density of GJ/tonne (13), and are typically available at 6-10% moisture content (14), so on a dry weight basis, the energy content is around 18.8 GJ/tonne 9. This equates to an energy use of 10,133,200 GJ each year. Given that lignin has a lower heating value of 24.5 GJ/t, if lignin was to substitute for all of the estimated wood pellet market in 2008, this would provide a market for 413,600 tonnes of lignin pellets each year. 9 Based on the assumption that wood pellets contain 10% moisture content and that the energy content is 17 GJ/ odt. This would be a worst case scenario. 11

13 3.0 Viability of the NREL Clean Fractionation Process. In general, economic data regarding different fractionation technologies is not readily available. A detailed economic modelling of the NREL Clean Fractionation process was carried out in 2004 (7), and although it is based upon costs and engineering parameters for the year 2000, it provides an indication of the effects of throughput and the relative different minimum selling prices which were required at the time. The NREL analysis primarily looked at the viability of the process with regard to processing of corn stover to ethanol in a plant with 2,000 tonnes per day throughput (equivalent to 657,000 tonnes per year assuming an uptime of 90%). Corn stover was assumed to have a price of $ 30 per dry tonne (equivalent to / dry tonne in 2000). This is substantially cheaper than what would be used in the UK; for example, the average wheat straw price in 2000 was / tonne (15) (at 15% moisture) equivalent to 34.3/ odt. Two scenarios were investigated, namely; 1. Using Clean Fractionation to treat a portion of the biomass feed to produce a high value cellulose and/or lignin. This scenario assumes that 25% of the material in the plant is diverted towards clean fractionation; the remaining 75% is pre-treated. 2. Using Clean Fractionation to treat all of the biomass feed, so that the products obtained would be lignin, hemicelluloses and cellulose. For both of these extremes, it is assumed that all of the hemicelluloses sugars are diverted to the main bioethanol process for conversion to ethanol, and any cellulose not sold as a high value product is returned to the main bioethanol for conversion to ethanol. Any lignin not sold as a high value co-product, is returned to the bioethanol process to provide heat and power to the plant. 3.1 Modelling on 2000 Data Figure 4 below show the influence of throughput on the minimum cellulose and lignin selling price which must be obtained to make the process economic. All hemicelluloses are assumed to be sold for a flat rate of 5.6 cents per lb (equivalent to /t in ) and are assumed to be used in ethanol production. The analysis found that one, or both of the lignin or cellulose components needed to be sold for high value markets for the Clean Fractionation process to be economic. In general, as throughput increases, the minimum selling price at which the lignin and cellulose components would need to be sold for decreases significantly. 10 Based on an exchange rate of 1 US $ = , the average exchange rate for all of

14 Figure 4 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation process given a daily throughput of 2,000 tonnes or 500 tonnes of corn stover per day Source: Jechura (7). The original units of $ per lb have been converted to /tonne. Using the model in Figure 4, we can investigate the effects of different scales of production on the minimum selling price for both lignin and cellulose. In these scenarios, we use figures for both world sugars and Northern Bleached Softwood Kraft (NBSK) pulp for 2000, to facilitate comparisons with the modelling assumptions in Figure 4 above. In 2000, the average world sugar price (free market) was 8.08 US cents per lb (or per tonne 11 ) (16). The price for NBSK pulp for the first week of January 2001 (so roughly indicative of prices for the end of 2000), were $708 per tonne, equivalent to per tonne 12. NBSK is used as a benchmark pulp price, however, dissolving pulp (which would be the quality of material arising from the Clean Fractionation process) is known to consistently trade at a premium over NBSK. The price differential between the minimum selling price on the graph and the assumed market selling price is referred to in the scenarios below as the margin, which is either profit or needs to take into account processing costs to other products as described below. 11 Based on an exchange rate of 1 US $ = , the average exchange rate for all of Based on an exchange rate of 1 US $ = , the average exchange rate for the first week of January

15 There are two major points to be borne in mind when looking at the figures which follow: 1) The margin between minimum cellulose selling price and sugars needs to account for both the capex and opex costs of cellulose breakdown to sugars, thus the margin is an overestimate of what would occur in reality 2) The margin between the minimum selling price and NBSK will underestimate what the margin is for selling the cellulose product to a dissolving pulp market as dissolving pulp trades at a premium over NBSK. Scenario tonnes per day throughput Figure 4 shows that when lignin brings nil return, the minimum cellulose selling price is around 210 per tonne, whilst when lignin prices increase to around 150 per tonne, the minimum cellulose selling price decreases to around 120 per tonne. Given that the breakdown of cellulose to provide sugars incurs both capital and operating costs, and assuming that the sugars are sold at /tonne, the margin varies from a loss of /tonne to a loss of 2 /tonne depending on the selling price of the lignin. The revenue which could be obtained by selling the cellulose for high value markets such as dissolving pulp markets clearly exceeds the minimum cellulose selling price required under all situations. Assuming that the pulp is sold for per tonne 14, at a minimum cellulose selling price of 210 /tonne, the margin is at least /tonne, while at a price of 150 /tonne, the margin is at least /tonne. Scenario 2 2,000 tonnes per day throughput Clearly, with increased throughput, the minimum selling prices for both lignin and cellulose decreases markedly. If cellulose can be sold for 190/ tonne, lignin can be sold for nil, whilst when lignin prices increase to 150/ tonne the minimum selling price for cellulose can approach 5 / tonne. Given sugar prices of /tonne, margins of between a loss of /tonne and positive margin of 185 /tonne are available for the capex and opex associated with cellulose breakdown to sugars. The revenue which could be obtained by selling the cellulose for high value markets such as dissolving pulp is extremely favourable at higher throughputs. At a minimum cellulose price of 190 /tonne, the margin is at least , at a minimum cellulose price of 5 /tonne, the margin is at least Average world sugar price for Average NBSK pulp price for 1 st week in January

16 In summary, the margins for selling the cellulose derived from Clean Fractionation as a high quality cellulose product such as dissolving pulp is always greater than selling the cellulose to make sugars, given that the cellulose derived from Clean Fractionation is a finished high value product, whilst if sold for sugars, there is margin needed for capex and opex requirements associated with this transformation. It is clearly preferable therefore, to utilise the cellulose derived from Clean Fractionation processes in higher value markets wherever possible. This is especially true with smaller scale plants. 3.2 Effect of Improved Solvent Recycling and Recovery One of the principal concerns highlighted by Jechura (7) was that the market economics were unfavourable for the Clean Fractionation process as originally modelled if ethanol was the principal end use market. Ethanol is a low priced commodity, so low prices for the cellulose component were required, this, in turn suggests that lignin prices would need to be sold at a price which would be more appropriate for a speciality chemical feedstock. Jechura (7) modelled a scenario in which there was significantly more efficient recovery of the MIBK solvent combined with the assumption that ethanol could be recycled as part of an integrated bioethanol production process, effectively reducing the cost of the solvent ethanol to zero. Figure 5 below shows the projected effects of significantly improved solvent recycling and recovery on the required minimum cellulose and lignin selling prices in the Clean Fractionation process. Clearly, there is considerable scope for the economics of the process to be improved with further research and development. For both the 500 tonne per day and 2,000 tonne per day scenarios, the minimum lignin and cellulose prices are lower than for the 2,000 tonne per day situation modelled in Figure 4. 15

17 . Figure 5 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation process given a daily throughput of 2,000 tonnes or 500 tonnes of corn stover per day and given improvements to the process parameters. Source: Jechura (7). The original units of $ per lb have been converted to /tonne. 3.3 Modelling on 2007 Data The analysis above is broadly representative of prices in This is not necessarily the case for 2009 or indeed 2020, as prices for commodities can vary significantly with time as shown in Figure 1 and Figure 3. The Scenarios below are the same as quoted above, but are based on average figures for pulp and sugar prices for 2007, 109 /tonne for sugar and 396 /tonne for pulp. We have used the average price for 2007 as it is before the pricing increases of 2008, and the subsequent crash in prices, and thus more accurately represent long term trends in pricing. 16

18 Figure 6 - NREL model of minimum selling price for cellulose and lignin derived from the Clean Fractionation, as for Figure 5 but using a base year of 2007 Labels on the axis are based on those in Figure 4, but have been modified to represent 2007 figures, using the average RPI per year between 2000 and Scenario tonnes per day throughput Figure 4 shows that when lignin brings almost nil return, the minimum cellulose selling price is around 260 per tonne, whilst when lignin prices increase to around 190 per tonne, the minimum cellulose selling price decreases to around 150 per tonne. Given that the breakdown of cellulose to provide sugars incurs both capital and operating costs, and assuming that the sugars are sold at 109 /tonne, the margin varies from a loss of 151 /tonne to a loss of 41 /tonne depending on the selling price of the lignin. Assuming a price of 396 /tonne for NSBK pulp, at a minimum cellulose selling price of 275 /tonne, the margin is at least 121 /tonne, while at a price of 40 / tonne, the margin is at least 356 / tonne. Scenario 2 2,000 tonnes per day throughput Clearly, with increased throughput, the minimum selling prices for both lignin and cellulose decreases markedly. If cellulose can be sold for 115 / tonne, lignin can be sold for almost nil, whilst when lignin prices increase to 190 / tonne the minimum selling price for cellulose can approach 10 / tonne. 17

19 Given sugar prices of 109 /tonne, margins of between 6 /tonne and 99 /tonne are available for the capex and opex associated with cellulose breakdown to sugars. Given a NBSK price of 396 / tonne, at a minimum cellulose price of 115 /tonne, the margin is at least 281 / tonne, at a minimum cellulose price of 10 /tonne, the margin is at least 386 /tonne. 18

20 Works Cited 1. oanda.com. FXHistory : historical currency exchange rates. oanda.com. [Online] Index Mundi. Sugar Monthly Price. Index Mundi. [Online] [Cited: 17 August 2009.] 3. OECD-FAO. OECD-FAO Agricultural Outlook FAO. [Online] [Cited: 27 July 2009.] 4. Defra. Sugar - European Union Regime. Defra Farming. [Online] 11 January [Cited: 27 July 2009.] 5. Personal Communication to A. Higson, Assessment of Ethanol Production Options for Corn Products. Gulati, M, et al. 1996, Bioresource Technology, pp Jechura, J. Analysis for Go/No-Go Decision Whether Clean Fractionation (CF) is a Viable Near-Term Pretreatment Option for the OBP Sugars Platform Within the Biorefinery. Golden, Colorado : NREL, Skibar, W, et al. Assessment of Current Activity in the Production of Platform Chemicals from Renewable Sources and Horizon Scan ro Forecast Potential Future Developments in Science and Technology in Biocatalysis. Chester : Industrial Biotechnology Innovation and Growth Team (IB-IGT), IB IGT T&MWG 09/ Black, S. Clean Fractionation Questions. 20 July Paperloop Inc. AV Group Ramps Up in Dissolving Market. Pulp and Paper. [Online] September [Cited: 15 July 2009.] RISI. Spot viscose dissolving pulp prices drop more than 30% in Asia. RISI. [Online] 4 August [Cited: 4 August 2009.] UKPIA. Briefing: Heating Oil Supply. UKPIA. [Online] December [Cited: 4 August 2009.] eating%20oil%20winter%2007-8%20final%20rev.pdf. 13. Biomass Energy Centre. Typical Calorific Value of Fuels. Biomass Energy Centre. [Online] no date. [Cited: 7 August 2009.] ma=portal. 14. National Energy Foundation. About Wood Pellets. The Log Pile Website. [Online] [Cited: 7 August 2009.] 15. Prices of Selected Feeding Stuffs in Great Britain - Statistics. Defra. [Online] [Cited: 12 August 2009.] International Sugar Organisation. Sugar Year Book. London : International Sugar Organisation, ISBN

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