Gylling, M.

Heding, N.

Rasmussen, Søren Kjærsgård

Online Research Database In Technology

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New and emerging bioenergy technologiesPublication date:2003Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Gylling, M., Heding, N., & Rasmussen, S. K. (2003). Trends and perspectives in bioenergy supply in Denmark.In H. Larsen, J. Kossmann, & L. Sønderberg Petersen (Eds.), Risø energy report 2. New and emergingbioenergy technologies (pp. 13-17).  (Denmark. Forskningscenter Risoe. Risoe-R; No. 1430(EN)).4Risø Energy Report 2IntroductionEnergy security and environmental protection have beenthe objectives of Danish energy policy over the last fewdecades.Energy security was the main driving force for severalyears after the energy crisis of 1973–4. The idea was tomake Denmark less dependent on foreign energy, espe-cially imported oil, by adopting multiple energy sources,especially natural gas, and developing new “alternative”energy sources.Support programmes and tax incentives were launchedto promote the development of renewable energysources, including bioenergy, wind power and CHP, andof systems to increase energy efficiency and improvesupply security for Denmark’s own oil and gas.In bioenergy, the most important factor was a politicalagreement in 1993 which obliged large power plants toburn 1.2 million t/y of straw and 0.2 million t/y of woodbefore 2000. This was followed by a decision to converta number of district heating plants to biofuels and CHP.In the past few years the political focus has shiftedtowards opening up the natural gas and power marketsas part of Denmark’s transition to a free market withinthe European Union. Support for energy R&D has beenmuch reduced since the end of 2001.Since the 1992 Rio “Earth Summit”, however, growingconcern for the global environment has replaced the oldagenda of supply security with a new mandate to main-tain and enlarge Denmark's role as a pioneer in sustain-able development.As a result, Danish commitment to the Kyoto Protocolhas become a strong driving force for energy and envi-ronmental policy, resulting in various energy plans withspecific targets for greenhouse gas reductions and waysof reaching these targets. In support of this, the DanishParliament has decided that no new coal-fired powerplants will be built. Parliament has also decided thatnuclear fission, which by its nature is CO2-neutral, willnot be used for power production in Denmark.BioenergyDanish energy production based on biomass from agri-culture and forestry, including biogas, made up around45% of the country’s total renewable energy productionin 2001 (Table 2). Straw and firewood are the mostimportant biofuels, followed by industrial wood waste.Wood fuel in Denmark is available as industrial woodwaste (raw or as wood pellets), forest chips, firewood anda very small amount of coppice willow from short-rota-tion forestry. Firewood, and to an increasing extentwood pellets, are mainly used to heat private houses.Most industrial wood waste is used for industrial heating,while wood chips are primarily used in CHP plants.Wood as an energy resource contributes 25.5 PJ (Table 2),equivalent to approximately 0.6 million tones of oil.Table 2 illustrates the distribution among the individualwood fuels, but does not include wood waste in the formof broken or worn-out furniture, paper etc.Trends and perspectives in bioenergy supply in DenmarkMORTEN GYLLING, DANISH RESEARCH INSTITUTE OF FOOD ECONOMICS, NIELS HEDING, DANISH FOREST AND LANDSCAPE RESEARCH INSTITUTEAND SØREN K. RASMUSSEN, RISØ NATIONAL LABORATORYTrends and perspectives in bioenergy supply in Denmark 13Table 2. Bioenergy production from agriculture and forestry (2001) Fuel type Resource contribution (PJ)Non-wood Straw 13.7Urban waste 33.0Biogas 3.0Wood Firewood 12.6Industrial wood waste 7.2Wood chips 3.2  (6.5 in 2002)Wood pellets 2.5  (4 in 2002)Total 75.2  (approximately 80.0 in 2002)Note: 1 PJ is equivalent to the lower calorific value of 23,810 t of oil. Source: Energistatistik 2001; Danish Energy Agency. 4Risø Energy Report 2Since the late 1990s there has been an increasing inter-national trade in wood chips and wood pellets, and Den-mark now imports substantial amounts of these. TotalDanish consumption of wood is approximately 8 milliont/y, of which 6 million t/y is imported and Danish forestssupply the rest. The intention is that most of this woodends up as fuel, either directly or after having been usedfor other purposes first. In the latter case, however,national statistics class the wood simply as “waste”, mak-ing it hard to distinguish from other kinds of waste.Under the 1993 “bioenergy agreement” two new CHPplants started production in 2002, one using 200,000 t/yof wood chips and the other 150,000 t/y of straw.Only a very small part of Denmark’s approximately 30million t/y of animal manure is currently used to pro-duce biogas. A number of relatively large on-farm biogasplants started production in 2002, the last centralisedbiogas plant having been put into production in 1998.Changes in subsidies for green electricity produced onnew plants built after 2002 have put an economic halt tonew biogas plants. However, the recent agreement forsubsidies for electricity from new biogas plants hasopened up for a number of new biogas initiatives.The Danish bioenergy industryThe bioenergy technologies currently most developed inDenmark are those for biogas production (Table 3). Thebasic raw material is animal manure, of which Danishfarms produce 34.1 million t/y (including 27.0 milliont/y of slurry).Green Farm Energy A/S has developed an advanced bio-gas plant that runs on manure, supplemented with otheragricultural waste products containing less water, such asstraw or future energy crops. The plant also removesnitrogen and phosphate from its waste stream, thus solv-ing the problem of how to stop these two nutrients pol-luting watercourses.Another novel concept is to use manure and wheat strawin a combined process that yields bioethanol as well asbiogas (Chapter 6.4).Reference 2 also lists a large number of manufacturersand suppliers of wood-fired boilers.Rapeseed is the only oilseed crop currently grown byDanish farmers. Several mills are now refining cold-pressed rapeseed oil so that it can be used in heating sys-tems.The potential for using rapeseed oil as a source ofbiodiesel has not yet been fully explored in Denmark.Emmelev Mølle is the only producer of rapeseed oilmethyl esters (RME, or biodiesel). Due to lack of nationaltax exemptions for liquid biofuels most of this isexported to Sweden and Germany instead of being usedin Denmark.When biomass such as wood and straw burns, a numberof chemical processes convert the carbonaceous materialinto a mixture of gases which are subsequently com-busted. It is possible to use the energy contained in thebiomass more efficiently by separating the processes ofgasification and combustion. New two-stage gasifier(Table 3) plants use fixed-bed or fluidised-bed reactors toproduce a mixture of carbon monoxide and hydrogen,which can then be burned either alone or combined withgas from other sources. A challenge for gasification tech-nology is to remove the corrosive ash created by the highlevels of chloride and potassium present in plantbiomass or high molecular tars and hydrocarbons fromthe pyrolysis and gasification process. Ashes frombiomass only, are recycled to agriculture and forestry.Denmark’s forest area of approximately 0.5 million hasupplies an increasing amount of firewood and forestchips. In the light of the Government’s plan to doublethis area of forest, Denmark’s total wood fuel resourceswill increase in the years to come. Afforestation takesplace on agricultural land and will therefore result in aTrends and perspectives in bioenergy supply in Denmark14Company Technology typeBioscan A/S BiogasGasCon BiogasGosmer Smeden On-farm biogasDansk Biogas A/S BiogasGreen Farm Energy A/S BiogasLundsby Bioenergi BiogasEmmelev Mølle RME, biodieselCowi with DTU / Vølund GasificationDanish Fluid Bed Technology GasificationHollensen GasificationCarbona / Skanska GasificationTable 3. Bioenergy industry in Denmark. Source: this manuscript. 4Risø Energy Report 2proportional decrease in the straw and energy croppotential.EnvironmentAs a small country, Denmark is heavily influenced byinternational agreements on energy and environmentalissues, and the increasing internationalisation of mar-kets. To avoid being swamped by outside forces, Den-mark must therefore secure the greatest possible influ-ence in international affairs concerning energy and theenvironment. This will help the country achieve its goalsand create the best conditions for its domestic environ-ment and economy.The EU Directive has set as an “indicative goal” that by2010, 29% of Denmark’s electricity should be producedfrom renewable sources, including biomass and bio-waste. Agriculture and forestry provides 47 PJ in 2002and urban waste is predicted to contribute with constantamount of 33 PJ.Forest chips result from first and second thinning, fromharvesting over-mature and partly-dying pine planta-tions, and from tops following clear-cutting. Wood chipshave become even more important as a fuel over the twolast decades, and their significance is underlined by theDanish national obligation to reduce CO2 emissions.The production of biogas from manure will also affectthe environment. In particular, the ability of large on-farm biogas plants to remove nitrogen and phosphatewill reduce the quantities of these nutrients pollutingwatercourses and coastal areas. Instead, farmers will beable to recycle the nitrogen and phosphate for crop pro-duction.What can be done?In previous decades Danish energy policy was marked bystrong public involvement at every stage and a pioneer-ing approach towards global sustainable development.This has been replaced by a new balance between generaleconomic growth and the development of energy tech-nology. The priority in energy policy is now liberalisa-tion, with the aim of meeting Denmark’s internationalenvironmental commitments and at the same timeexpanding the economy.The Kyoto Protocol’s flexible mechanism shall be used asan integrated part of the Danish climate change policy inorder to fulfil the Kyoto commitment. The Danish Gov-ernment has started a process in order to analyse how cli-mate target in Denmark is to be obtained most cost effec-tively. The use of the Mechanism plays a central role inthe planning of the process. The planning is carried outin co-operation between the Ministry of Finance, Envi-ronment, Foreign Affairs, Taxation and the Ministry ofEconomic and Business Affairs (Energy) to assist theenergy industry in implementation of the JI and theCDM tools. The JI projects are expected to be launchedprimarily in the Eastern Europe while CDM projects areto be carried out in the developing countries.Future bioenergy resourcesDanish bioenergy from agriculture and forestry is cur-rently based mainly on waste materials such as straw,waste from the wood industry and forest thinnings.Under the revised bioenergy agreement, by the end of2004 the electricity companies are obliged to use 1.4 mil-lion t/y of biomass, including 930,000 t/y of straw. Agri-culture, forestry and the wood industry can easily supplythese quantities of biomass.Given the present political strategies for energy and theenvironment, it is difficult to foresee any substantialincrease in the demand for solid biofuels from agricul-ture beyond 2004. At present there is no tax exemptionsor subsidies for liquid biofuels and the future nationalTrends and perspectives in bioenergy supply in Denmark 15Table 4. Estimated biomass resources from agriculture for energy purposes, 2015. Based on Gylling et al. 2001.Scenario 2000 2015 2015 2015Unit Current Reference Environmental MarketTotal straw production tonne 6,484,000 5,857,000 4,840,000 6,758,000Available straw for energy purposes tonne 2,663,000 2,445,000 1,414,000 3,494,000PJ 37.4 34.3 19.8 49.0Available area for energy crops ha 186,000 168,800 160,000* 85,000Potential energy production PJ 27.9 25.3 24.0 12.8Total potential straw and energy crops PJ 65.3 59.6 43.8 61.8* 85,000 hectares ESA – set-aside. + 75,000 hectares set-aside4Risø Energy Report 2politics is not yet known. If demand were to increase,however, current biofuel resources would soon be fullyutilised. The logical next step would be to grow dedicatedenergy crops, though under the present Common Agri-cultural Policy (CAP) this would only be economic onset-aside land.A study by the Danish Research Institute of Food Eco-nomics estimates potential production of biomass forenergy in the range 44–62 PJ/y, depending on develop-ments in the framework conditions for Danish agricul-ture (Table 4).The study outlines three different agricultural scenariosup to 2015. The first scenario is a reference case in whichcurrent trends are simply extrapolated. The “environ-mental” scenario proposes a higher degree of environ-mental awareness, while the “market” scenario imaginesa future in which agriculture becomes more competitivein economic terms.The estimate of total biomass available for energy pro-duction is based on the assumption that set-aside land isused to grow a mixture of energy crops; whole cropwheat and triticale, plus willow coppice. The averageannual yield is estimated at 9 t/ha of dry matter. The ref-erence and market scenarios estimate the amount ofenergy available from biomass at 59.6 PJ and 61.8 PJrespectively, though the market scenario includes about40% more straw because grain production is higher. Theenvironmental scenario yields only 43.8 PJ of bioenergy,mainly because grain production is lower.Straw and energy crops (whole crop grain, willow andMiscantus) are to a large extent interchangeable in largemulti-fuel burners (Gylling 2001), but differences in stor-age characteristics need to be taken into account whensetting up the biofuel production chain in order to securean economic efficient all year supply.Fuel pellets seem to be an expanding market. Wood pel-lets currently account for almost the entire market, but arecent Danish study (Nikolaisen 2002) found that fuelpellets made from mixed biomass sources can providethe same quality as wood pellets, as long as the rightingredients and additives are used.Most firewood comes from thinning and clear-cutting ofhardwood stands, in the form of smaller trees, tops andbranches. Official statistics show that Danish forestryproduces approximately 450,000 m3/y (solid volume) offirewood, but this does not take into account firewoodtaken from gardens and parks.There have been three assessments of forest fuelresources in Denmark. Table 5 shows predictions for fuel-wood resources (forest chips plus forest firewood) takenfrom the most recent of these assessments (Nord-Larsen& Heding, 2003), which extrapolates from the currentnational forest inventory using models for forest growthand yield. The figures cover three ten-year periods(2000–2009, 2010–2019 and 2020–2029), each underthree scenarios in which utilisation of forest resourcesbecomes progressively more intense.The three scenarios are:1. Whole-tree chips from early thinning and from finalfelling of over-mature pine.2. In addition to Scenario 1, forest chips from branchesand tops harvested during final felling.3. In addition to Scenario 2, forest chips from tops andbranches harvested during later thinning.Under all three scenarios, potential production of forestchips exceeds the current figure by a factor of 1.5–2.ResearchResearch on wood fuels has changed direction over theyears. In the 1980s the focus was on harvesting tech-niques and long-term storage. In the 1990s emphasischanged to the physical characterisation of wood chips,their storage properties, and how to optimise silvicul-tural regimes to produce more chipping material.Current research topics include reducing the harmfuleffects of mould and understanding the nutrient bal-ances associated with intensive chip harvesting fromTrends and perspectives in bioenergy supply in Denmark16Table 5. Danish fuel-wood resources for three scenarios over the next 30 years. Source: Nord-Larsen & Heding, 2003.Time periodScenario Fuel-wood production 2000–2009 2010–2019 2020–20291 Volume (million m3 solid volume/y) 0.9–1.3 0.9–1.3 0.9–1.3Energy (PJ/y) 8–11 8–11 8–112 Volume (million m3 solid volume/y) 1.1–1.5 1.1–1.5 1.2–1.6Energy (PJ/y) 9–12 9–12 9–133 Volume (million m3 solid volume/y) 1.3–1.7 1.3–1.7 1.4–1.8Energy (PJ/y) 11–14 9–14 9–154Risø Energy Report 2whole trees. More use of forest fuels means more woodash, and another research topic is how ash can bereturned to the forest floor – a disposal route that is hin-dered by current regulations. Yet another research area ishow to improve the performance of the wood fuel sup-ply chain, which at the moment is very tight.Future R&D should also aim to create new plant strainswith high energy contents and other characteristics tomake them suitable as biofuels. New chemical and bio-logical transformations, as well as improvements toexisting separation and concentration processes, areneeded for the production of bioethanol, biodiesel andhydrogen and other biofuels.Danish farmers will continue to grow rapeseed if for noother reason than its advantages in crop rotation, so asignificant and predictable amount of rapeseed oil can beexpected. To make it ideal for biodiesel (RME) produc-tion, however, rapeseed needs to be developed so that itsoil is more resistant to high temperatures and oxidation.Other technical advances would allow rapeseed to beused to create biolubricants as well.To meet these goals a multitude of instruments are usedby Danish R&D connecting public and private sector.The funding is provided by the public, national as well asEU and for some specialized issues by DOE. Privateinvestors show increasing interest in this field to developlocal industry which address European agrofuels chal-lenges, because the Danish market is limited in size.Trends and perspectives in bioenergy supply in Denmark 17

Trends and perspectives in bioenergy supply in Denmark

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Trends and perspectives in bioenergy supply in Denmark

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