TECHNOLOGY-ANALYSIS: Biogas -

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1 TECHNOLOGY-ANALYSIS: Biogas - Overview of Key Technologies, Benchmarking and Potentials (Summary) This report has been prepared within the project»smart Energy Network of Excellence, Nr. 5403«, Interreg IV Program Italy Austria Project co-funded by the European Union, European fund for regional development. Authors: Sirio Rossano Secondo Cividino. Università degli Studi di Udine

2 Biogas Technologies 1. Introduction Biogas technology Biogas from Energy Crop Digestion Crops used in anaerobic digestion Technology for anaerobic digestion of crops Substrate used in biogas plants ( Austria example) Significance and potential of crop digestion Anaerobic digestion of animal manure Good agricultural practice for the application of digested manure Biomethane technology Conclusions: Future significance of biogas from biomass Future significance of biogas in Austria Future significance of biogas in Italy [2]

3 1. Introduction. Biogas is produced during anaerobic digestion of organic substrates, such as manure, sewage sludge, the organic fractions of household and industry waste, and energy crops. It is produced in large scale digesters found preliminary in industrial countries, as well as in small scale digesters found worldwide. Biogas is also produced during anaerobic degradation in landfills and is then referred to as landfill gas. The worldwide biogas production is unknown, but the production of biogas in the European Union was estimated to be around 69 TWh in The biogas production in the European Union has steadily increased over the last years (Fig 1). Fig 1:Biogas production in the European Union between 2002 and 2007 (by IEA Bioenergy s Task 37: Energy from biogas and landfill gas Biogas consists mainly of methane and carbon dioxide and it can be utilized as a renewable energy source in combined heat and power plants, as a vehicle fuel, or as a substitute for natural gas. The methane in the biogas can also be utilized in industrial processes and as a raw material in the industry. Production and utilization of biogas has several environmental advantages such as: It is a renewable energy source; It reduces the release of methane to the atmosphere compared to e.g. traditional manure management or landfills; It can be used as a substitute for fossil fuels; A high quality digestate that can be used as a fertilizer; [3]

4 For some applications, where it is important to have a high energy content in the gas, e.g. as vehicle fuel or for grid injection, the gas needs to be upgraded. The energy content of biogas is in direct proportion to the methane concentration and by removing carbon dioxide in the upgrading process the energy content of the gas is increased. Upgrading of biogas has gained increased attention due to rising oil and natural gas prices and increasing targets for renewable fuel quotes in many countries. New plants are continually being built. The number of upgrading plants was around 100 in 2009 (Fig. 2). Fig. 2 Total number of upgrading plants from 1987 to The process of upgrading biogas generates new possibilities for its use since it can then replace natural gas, which is used extensively in many countries. However, upgrading adds to the costs of biogas production. It is therefore important to have an optimized upgrading process in terms of low energy consumption and high efficiency giving high methane content in the upgraded gas. It is also very important to minimize, or if possible avoid, emissions of methane from the upgrading process, since methane has a greenhouse gas effect 23 times greater than that of carbon dioxide. This means that the methane content in the reject gas, in the water from a water scrubber, or in any other stream leaving the upgrading plant should be minimized. Several techniques for biogas upgrading exist today and they are continually being improved. (Fig. 2) In parallel, new techniques are under development. These new developments, both for new and more traditional techniques, can lower investment costs and operational costs. The developments [4]

5 can also lead to other advantages such as lower methane emission which is important from both an economical and environmental perspective. Fig. 3 Biogas plants in Germany (2009) Once produced, biogas may be burnt in traditional boilers to produce heat or be utilized as fuel for generation of electric power or combined heat and power (CHP/cogeneration) by using different types of technology, mature and not, such as internal combustion engines, gas turbines, and finally the innovative fuel cells or micro-turbines. Biogas can be used to produce chemical compounds, as fuel in the automotive sector or be injected into the gas grid, these last two applications arousing ever more interest.its diverse uses depend on its different commodity quality, deriving from the type of chemical refining it undergoes, on various levels, to eliminate contaminants [such as, nitrogen (N2) and oxygen (O2), hydrogen sulphide (H2S), carbon dioxide (CO2) or water (H2O)]. Naturally, these treatments affect production costs and consequently also the final price of the electricity generated. For example, if the purification process is not driven, and so it is simpler and less expensive, the final designated use of the biogas produced is for heat production, using boilers, present on the same site. If the treatment process is middling, the most convenient use is that of generating heat and electricity by means of CHP systems or gas turbines. On the contrary, if all the contaminants are eliminated from biogas, i.e. pure methane (CH4) is obtained, it may be used as fuel for vehicles, to generate electricity and heat with fuel cells, for the production of chemical compounds or simply to be injected into the gas grid, and therefore mixed with natural gas of fossil origin. Apart from the various possible uses, nowadays biogas is mainly used to generate electricity (2/3 of the total amount, half of which obtained using cogeneration plants) and for the production of heat (the remaining 1/3). The annual production growth rate has been rather high in the last decade, that is 24% in 2002, 13% in 2003, 22% in 2004 and 15% in [5]

6 2005. The total value registered in 2005 was approximately GWh, that is, only 0.5% of total consumption of electricity in the EU (2700 TWh), reconfirming the leading position of Great Britain and Germany. (Fig 4) Fig 4 Production of electricity from Biogas Europe ( ) 2. Biogas technology 2.1 Biogas from Energy Crop Digestion The concept of crops for methane production (anaerobic digestion, biogas, methanisation or biomethanation) is not new. Early investigations on the biomethanation potential of different crops and plant materials were carried out in the 1930 s in the USA (Buswell and Hatfield, 1936), in the 1950 s in Germany (Reinhold and Noack, 1956), and in the 1980 s in New zealand (Stewart et al., 1984). Although the digestion of crop material was demonstrated, the process was hardly applied in practice. Crop digestion was not considered to be economically feasible. Crops,, crop byproducts and waste materials were occasionally added to stabilise anaerobic waste digesters. In the 1990 s steadily increasing oil prices and improved legal framework conditions, stimulated crop research and development. In Germany for example, the number of digesters using crops was 100 in At the end of 2010 approximately 6,000 biogas plants were in operation in Germany (Fig. 5) [6]

7 Fig. 5: Increasing number of biogas plants in Germany between 1990 and 2010 (Weiland, 2010) The majority use a mixture of manure and crops; % of all plants (between 5,400 and 5,700 plants) use crops. Several biogas plants employ mono-digestion. The steady increase in crop digesters in Germany can be directly attributed to the favourable supportive national legal framework coupled with the tariffs paid for renewable energy. Staggered feed-in tariffs (which depend on the electrical power capacity of the biogas plants) are guaranteed for the whole depreciation period of the investment. Feed-in tariffs also exist in other countries, for instance in Switzerland, the Netherlands and France. Other European countries apply tax exemptions (e.g. Sweden) or a choice of certificates and feed-in tariffs (e.g. UK) for renewable energy. France, Switzerland or Sweden do not offer subsidies specifically for crop digestion. 2.2 Crops used in anaerobic digestion Numerous plant species and plant residues have been tested for their methane potential. In principal, many varieties of grass, clover, cereals and maize, including whole plants, as well as rape and sunflower proved feasible for methane production. The literature typically refers to methane production in terms of m3.t-1 Volatile Solids (VS). Volatile Solids refer to that portion of solids that are organic or dry and ash free; solids that can either combust or biodegrade. For example, 1 t of Volatile Solid has an energy value of about 19 GJ while 1 mn 3 of methane (CH4) has an energy value of ca. 38 MJ. Thus for conservation of energy the maximum production of methane is 500 m3.t-1 VS (500 mn3 CH4 * 38 MJ/mn 3 = 19,000 MJ = 19 GJ = 1 t VS). This value may increase for example due to the presence of alcohols and acids in silage liquors. Depending on specific process [7]

8 conditions, a fairly wide range of methane yields, between m3.t-1 VSadded, is reported in the literature from anaerobic digestion of different crops (Table 1). Recent German practical experience showed mean methane yields of 348 m3.t-1 VS for ensiled maize and 380 m3.t-1 VS for whole plant ensiled barley (KTBL, 2009). A comprehensive data bank on crop yields, appropriate climate and growth conditions was elaborated in the recent EU funded CROPGEN project (Cropgen, 2011). Crops may be used for digestion directly after harvest. For year round availability of substrates, crops are frequently stored in silage clamps. Grass, for example, may be ensiled in a clamp or pit or it may be baled. In Irish conditions pit silage has a dry solids (DS) content of approximately 22% while bale silage has a dry solids content of about 30%. In drier climates such as Austria, grass is wilted (partially dried after cutting) prior to collection from the field and the resulting silage can have a dry solids content of up to 40%. The time of harvest varies for differing crops. Grass may be cut between two and five times in a season; the first harvest is as early as May (in the northern hemisphere). Sugar beet is harvested later than most crops, typically between November and January. Staggered harvest improves the possibility for co-digestion of fresh crops and reduces the amount of storage capacity required. The time of harvest can influence bio-degradability, and hence the methane yield. Late harvest (with longer growing period) usually leads to higher lignin content in grasses (Fig. 6), causing slower bio-degradation and lower methane yield. Work in Ireland indicated a yield of 440 m3 CH4. t-1 VSadded for grass silage from an early harvest of perennial rye grass (Thamsiriroj & Murphy, 2011) though average values from the scientific literature are lower, reflecting the fact that later cuts have a higher fibre content. Fig. 6: Phase composition of grass with advancing maturity [8]

9 2.3 Technology for anaerobic digestion of crops Numerous technical solutions are offered by the industry all of which are based on the same basic principle. Four distinct steps can be defined for crop digestion processes (Fig. 7): Harvest, pre-processing and storage of crops The anaerobic process configuration and process control Treatment, storage and use of digestate Treatment, storage and use of biogas Fig. 7 steps defined for crop digestion processes [9]

10 2.4 Substrate used in biogas plants ( Austria example) The convenient climate conditions and well-usable agricultural land enables the cultivation of a variety of renewable raw materials for processing in biogas plants. Based on the high alpine shares, which are primarily used for forestry, the resource potential is distributed very unequal. An extremely high density of biogas plants is mainly located in favourable areas of agriculture, as maize is by far the cheapest raw material for biogas production. The grassland areas have very large untapped potential uses (grass silage / green waste), which are used up due to higher raw material costs so far insufficient. Fig 8 Substrate-production costs in Cent/kWh Gross Energy yield (Source: Loibnegger 2008) For economical reasons, mainly energy crops (maize, grass silage, green waste) are used togetherwith animal excrement (manure) as a substrate. The energy production occurs automatically incompetition with food production, which always leads to public policy discussions Food products are only used in 40 % of the plants, although they have a particularly beneficial for the gas quality and profitability. Fig 9 Substrate used in biogas plants (Source: Tragner et al. 2008) [10]

11 Most plant operators cover their substrate requirements by domestic production, little more than a quarter entirely dependent on acquisitions. By energy crops maize is the principal alternative and is used in two thirds of the plants. Grass silage and green waste are also used. The higher raw material costs make in many cases an increased use unattractive. The use of grassland areas is still increasing in importance in the near future. The general trend of declining livestock production has a high potential in the future, as the preservation of diverse cultural landscape for the tourism industry is of great importance. 2.5 Significance and potential of crop digestion Crop digestion leads to increased activity in the agricultura sector by increasing demand for locally grown biomass. Furthermore, the cultivation of crops promotes investment in the rural economy and the production of disperse sustainable rural employment. Currently, most crops are grown as intensive monocultures. Annual monocultures are often associated with high rates of soil erosion. Some crops, like maize, deplete soil nutrients more rapidly than others, and might require significant levels of agrochemicals (fertilizer, pesticides); this can be minimised through recycling of digestate. High yield crops in Continental Europe may also depend on irrigation. The risks of water depletion and of pollution may occur. Nevertheless, if sustainability criteria are followed, (Cramer et al., 2006) the use of crops will lead to a reduction in GHG emissions through replacement of fossil fuels. No single crop can cover all specific requirements of the various local conditions. Comprehensive investigations for the selection of optimised plantation systems for different habitats have been started in countries such as Germany, The Netherlands and Austria (FNR, 2008). Results so far indicate the influence of soil quality, climate, water availability, crop rotation and last, but not least, the time of harvesting on biomass yield, methane production potential and consequently the overall economic viability. [11]

12 No single technology or renewable energy source could provide all of the world s future energy supply. Anaerobic digestion is under-utilised today in comparison to technologies for producing liquid biofuels, such as ethanol or biodiesel. At issue is the change in energy vector from liquid to gas. Anaerobic digestion is a versatile technology that requires relatively low levels of parasitic energy demand and can use a wide range of crops including lignocellulosic material such as grass. The energy balance of biogas crop systems is shown to be superior to first generation biofuel technologies, for example for ethanol production. Anaerobic digestion is a technology which can contribute substantially to the production of renewable electricity, renewable heat and renewable transport fuel. Anaerobic digestion allows for sustainable energy supply, rural employment, and security of energy supply. The biogas industry benefits greatly from policy and feed-in tariffs, as demonstrated by the German experience. The existing natural gas grid can provide the means for distribution of biomethane to both individual homes and businesses in many developed countries. The authors conclude that the following are of importance to a successful crop digestion industry: 1. Tariffs for anaerobic digestion of crops Good feed-in tariffs or other means of financial support are currently essential to achieve a viable financially sustainable biogas industry. The German system offers tariffs for biogas based on a number of criteria, including a bonus if crops are used as a feedstock for biogas production. The high investor security provided by the German feed-in-tariff has been a success, resulting in rapid deployment of renewables, the entrance of many new actors to the market and a subsequent reduction in costs. 2. Alignment of renewable energy and agricultural policy Family farm incomes have dropped significantly in recent years. Crops can afford a supplemental income for farmers while ensuring the production of sustainable biofuel and the maintenance of an aesthetically attractive countryside. A renewable energy tariff scheme coupled with an agricultural grant scheme provides an incentive to farmers to produce feedstock for biogas facilities and at the same time maintaining development of the rural economy. 3. Use of biomethane in transport Transport fuel may allow a good financial return on biogas and biomethane especially if feed-in tariffs are low. However, a biomethane infrastructure, such as injection points and gas compression stations, has high capital costs especially if a market for gaseous fuel is not in place. It is highly recommended to provide support to [12]

13 initiate a gaseous fuel infrastructure. Connecting biomethane with a captive fleet such as a bus service minimises investments for distribution of the gaseous fuel. 4. Targets for biomethane production For example, the National Biomass Action Plan for Germany has set targets for biomethane supply as a percentage of gas demand of 6% by 2020 and 10% by 2030.Denmark (which had a primary energy demand in 2009 of ca. 850PJ) has set a target of producing 20PJ of biogas by These targets are of great benefit to the biogas industry. Fehler! Verweisquelle konnte nicht gefunden werden. 2.6 Anaerobic digestion of animal manure Anaerobic digestion of animal manure has the general goal of convert organic residues into two categories of valuable products: on one hand biogas, a renewable fuel further used to produce green electricity, heat or as vehicle fuel and on the other hand the digested substrate, commonly named digestate, and used as fertilizer in agriculture. Fig. 10: the process of a typical biogas plant (manure) Digestate can as well be further refined into concentrated fertilizers, fiber products and clean water, all suitable for recycling. Co-digestion of animal manure with various biomass substrates [13]

14 increases the biogas yield and offers a number of advantages for the management of manure and organic wastes (Nielsen et al., 2002) and for mitigation of green house gas (GHG) emissions Figura 11 exemple o process diagramm of the biogas plan (manure) Anaerobic co-digestion of manure and digestible organic wastes from food industry is very important for the corporate economy of the biogas plants and for the socio-economic reasons (Braun and Wellinger, 2003). Biogas from co-digestion of animal manure and suitable organic wastes is also a very attractive solution from a socio-economic point of view, when biogas externalities, including environmental, human and animal health benefits are quantified and integrated in the overall economic benefits. Tab 1 Characteristics of manure production and methane production potential from different animal species. (Source: ASABE Standard D384.2 Manure production characteristics; NCSU EBAE ) [14]

15 Tab 2 Summary characteristics of digester technologies. (Source: EPA AgStar Handbook) For the socio-economic point of view, admixture of organic waste to animal manure digestion brings about important benefits concerning increased production of biogas and energy sales, savings related to organic waste treatment, improved fertiliser value of digestate and reduction of GHG emissions from manure and organic wastes (Nielsen et al., 2002, Olesen et al., 2005 and Hjorth et al., 2008). There are many types of biogas plants in Europe, categorised according to the type of digested substrates, according to the technology applied or according to their size. The biogas plants digesting manure are categorised as agricultural biogas plants, and they usually codigest manure and other suitable organic residues, many of them of agricultural origin as well. A common classification of the agricultural biogas plants is: the large scale, joint co-digestion plants and the farm scale plants. There is not a sharp delimitation between these two categories as elements of technology from one category are also common to the other. The EU-countries where the agricultural biogas plants are most developed are Germany, Denmark, Austria and Sweden and to a certain level the Netherlands, France, Spain, Italy, United Kingdom and Belgium. The technology is under current development in countries like Portugal, Greece and Ireland as well as in many of the new, Eastern European, member states, where a large biomass potential is identified. [15]

16 2.7 Good agricultural practice for the application of digested manure In order to achieve the environmental and economic benefits from the application of digested manure as fertilizer, some basic principles of good agricultural practice must be fulfilled (Holm- Nielsen et al., 1997): Always have a well established crusting surface in the storage tank with digested manure, to avoid ammonia volatilisation during storage. For the same reason, the digested manure must be pumped in at the bottom of the storage tank, to avoid stirring. The stored digested manure should be stirred just before it is applied to the crops, to ensure that sediments including the phosphorous are mixed into the entire volume. The storage tank for digested manure must be placed in sheltered from wind and other climate evaporation conditions. The digested manure must be incorporated in the soil immediately after application, or even better applied by injection in the top soil. Dragging or trailing hoses must be used when digested manure is applied in growing crops. The optimum weather conditions for application of digested manure as fertiliser includes: high humidity, low temperature and no wind. It is a possible to add acid to the digested manure when it is applied. This decreases the ph value and thereby the liability of ammonia to volatilise. The strategy concerning further and broader development of biogas production and for overcoming barriers could include: (Al Seadi, 2004, Holm-Nielsen and Al Seadi, 2004 and Holm-Nielsen and Oleskowicz-Popiel, 2007): Programmes to stimulate recycling of organic resources/organic wastes, especially of wet organic wastes. Support programmes for manure processing, with high energy recovery and safe measures of bio-security. Harmonization of animal manure storage and handling requirements. Focus on industrialized animal production, such as large scale pig production and similar business animal farms, with no or little land area for the recycle of nutrients through crop production. [16]

17 An overall strategy of mandatory harmony between animal production and farmland area suitable for manure application. Demands for maximum limits of nitrogen and phosphor loading rate on farmland. Improvement of the present technologies and reduced costs. R&D on small scale systems, going from economy of scale to economy of numbers. Improved post-treatment and separation technologies, aiming to overcome transport constraints. Finding and implementing new post-treatment technologies. Concentration on finding solutions to eliminate or avoid the bad odor in the vicinity of biogas plants. Programmes for active implementation and dissemination of biogas technologies and knowledge transfer to other countries around the world. An overall policy to stimulate green electricity production from renewable sources and to encourage use of renewables in combined heat and power systems. Stimulation of wider use of district heating networks, district cooling or heat recovery to processing industries, converting heat to cooling, especially in the warm climate areas, subtropics and tropics. 2.8 Biomethane technology Biomethane is a naturally occurring gas which is produced by the so-called anaerobic digestion of organic matter such as dead animal and plant material, manure, sewage, organic waste, etc. Chemically, it is identical to natural gas which is stored deep in the ground and is also produced from dead animal and plant material. However, there are several important differences between biomethane and fossil fuel derived methane despite the fact that both are produced from organic matter. Natural gas is classified as fossil fuel, whereas biomethane is defined as a green source of energy. Like its name suggests, fossil fuel derived methane is produced from thousands or millions of years old fossil remains of organic matter that lies buried deep in the ground. Production of fossil fuel derived methane, however, depends exclusively on its natural reserves which vary greatly from one country to another and are not available in limitless amounts. Biomethane, on the other hand, is produced from fresh organic matter which makes it a renewable source of energy that can be produced worldwide. Methane is about 20 times more potent greenhouse gas [17]

18 than carbon dioxide if released into the atmosphere. Furthermore, its use for power generation produces heat and emits carbon dioxide and some other gases but despite that biomethane has a number of environmental benefits which make it a green source of energy. Organic matter from which biomethane is produced would release the gas into the atmosphere if simply left to decompose naturally, while other gases that are produced during the decomposition process such as nitrous dioxide for instance further contribute to the greenhouse effect. Biomethane production eliminates the release of a great deal of methane and other harmful gases into the atmosphere. This is due to the fact that its production eliminates exposure of the decomposing organic matter to the air which prevents methane and other gases from escaping into the atmosphere. In addition, biomethane reduces the need for fossil fuels by which it further reduces the emissions of greenhouse gases into the air. By reducing the need for firewood, helps preserve the forests which in turn helps lower concentration of carbon dioxide in the atmosphere as the trees absorb carbon dioxide while releasing pure oxygen. The use of organic matter for biomethane production also improves hygienic conditions and quality of life in the rural areas, and reduces the risk of water pollution. Since biomethane is chemically identical to natural gas, it can be used for the same applications as natural gas. It can be used for electricity generation, water heating, space heating, cooking as well as to fuel vehicles. Biomethane offers great potential as an alternative source of energy, especially to fossil fuels. Despite the fact that its usability is known for quite some time, production of biomethane started only in the recent years as a result of the rising prices of natural gas and high electricity prices other fossil fuels as well as the threat of global climate change. [18]

19 3. Conclusions: Future significance of biogas from biomass Future significance of biogas from biomass In the early 20th Century many daily necessities such as energy, food, fodder, fertiliser and fibres were derived from agricultural biomass. As the 20th Century progressed, the traditional role of agriculture in energy supply diminished. Petrol and diesel driven vehicles replaced horses. However, with the progressive depletion of fossil fuels and the requirement for sustainable renewable energy, biomass is again an important raw material. Biomass may be converted to energy through microbial or thermal routes. Microbial conversion, as exemplified by biogas production has several advantages. While thermal energy generation (in particular combustion) destroys the structure of the organic substrate, with a final residue of inorganic ash, bioconversion permits retention of valuable organic structures and the remaining by-products can be advantageously recycled as fertiliser or soil conditioner. Closed nutrient cycles will become increasingly important especially when considering sustainability as assessed through monitoring greenhouse gas savings of bioenergy systems as compared to the displaced fossil fuel on a whole life cycle basis. Finding the optimal system in terms of crop yield, gross and net energy production per hectare, greenhouse gas reductions and sustainability is still a major challenge for the bioenergy sector. Land available for crop production is limited. The surface of the earth is mostly covered by oceans ( km2). Of the remaining area of km2, 55.7 % are covered by forests, 16.1 % (or km2) is deemed pastureland and only about 9.4 % (or km2) is arable land. The world s growing population requires growing quantities of food. This puts pressure on finite agricultural land resources which are required to produce feed for humans and animals, for biomass for industrial use, for alcoholic beverage production, and increasingly for energy production. Advantageously, biogas systems are very flexible. Biogas can also be produced from plants which are not used directly for human consumption; examples include grass. Soils which are marginal and unsuitable for food production can be used for the cultivation of crops. There is a considerable potential of biogas production from anaerobic digestion of animal manure and slurries in Europe, as well as in many other parts of the world. Anaerobic digestion of animal manure offers several environmental, agricultural and socioeconomic benefits throughout improved fertilizer quality of manure, considerable reduction of odors and inactivation of pathogens and last but not least production of biogas production, as clean, renewable fuel, for multiple utilizations. The last decade brought about huge steps forward, in terms of maturation of biogas technologies and economic sustainability for both small and large [19]

20 scale biogas plants. One of the driving forces for integrating biogas production into the national energy systems will continue to be the opportunities offered by biogas from anaerobic codigestion of animal manure and suitable organic wastes, which solves some major environmental and veterinary problems of the animal production and organic waste management sectors. Rewording manure processing for biogas production and for the environmental benefits provided by this would ensure the future development of the manure based biogas systems. 3.1 Future significance of biogas in Austria Around the year 2000, circa 120 biogas plants existed in Austria with an electrical installed performance of around 1.5 MW. The number of accepted biogas plants was increasing until 2009 up to 344 and an installed capacity of MW. At the moment 1 % of the annual consumption of electricity is covered by the biogas plants. The produced energy of 650 GWh covers the electricity consumption of around households. Nowadays the electrical average power of the plants is 300 kw. In comparison to the year 2003 where the electrical average power was at around 170 kw it is shown that there is a trend to build up larger biogas plants. In the meantime the effectiveness of plants has been increased sufficient up to 40 %, which is almost the performance of a caloric generating plant. In the future small plants should be promoted, which will have an efficient rejected heat system and the usage of local resources. The plants are mainly concentrated in three federal states. 2/3 of the plants are in agricultural andcattle regions of Lower Austria, Styria and Upper Austria, because liquid manure and maize is predominantly used in the plants. For the further expansion of the biogas sector, new energy policy pulses are needed. Biogas has the potential to become a future key technology, since the energy services provided are very versatile power, heating, cooling, fuel, natural gas substitute. Decentralized energy supply for future regional development is an indispensable contribution. On the one hand it reduces the energy import dependence and the other; it increases the local economy by creating new jobs. Currently 1,500 people work in the Austrian biogas industry [20]

21 3.2 Future significance of biogas in Italy In the Italian biogas plants it is used mainly as substrates animal slurry and manure (cows and pigs, potential estimated 130 billion t/y), agroindustrial residues and energy crops (mainly maize silage, also sorghum). Of them about 50% operate in co-digestion of manure with energy crops and residue of agriindustrial residues (inter alia tomatoes, potatoes, onions and other vegetables residuals). Normally a 1 MW el. output needs a crops surface (maize silage) to be fed in co-digestion with manure. Normally in the flat area (alongside Po rivers) the harvesting productivity (whole plant) with irrigation supply facilities can reach t/ha/y maize and a second harvesting during the same year (e.g. Triticale) can be further more harvested about t/ha/y. GSE (Dec. 2008) in Italy reports a production of about 1.6 TWh electricity (+10,5% compared to Dec 2007) from biogas of which 85% comes from landfill (1.355 GWh) and from agricultural 14% (ca. 230 GWh). The whole biogas sector represents about 0.47% of the national total consumption which in Italy The potential of biogas in Italy has been estimated in about 20 TWh/y which a power capacity installed of MWel or in term of biogas produced is about 6.5 billion Nmc (CRPA.it). In Italy is consumed annually about billion Nmc of fossil methane (Russia, Libya, Algeria and near east) (trend increasing) and the methane national production is about in 8 billion NMc (trend decreasing). At the moment (January 2012) there is no biomethane plant (upgrading biogas) in Italy based on agricultural and agri-industries residues Concerning the development of plant number, in December 2008, including the landfills biogas plants (141 plants with a total power of 210 MWe), there were around 360 operating plants with a total capacity of 345 MWe. In Sept there were 401 plants qualified by GSE (see below) and the power installed has reached 345 MWe. There are around biogas plants which have a power of 1 MWe (Sept. 2009). In Rome there is a private company (AMA) managing waste which is processed and subsequently landfilled. It produces a considerable amount of biogas used mostly for their own electric power plant and partly to provide biomethane for AMA waste collection vehicles (collecting HD). (Biogasmax.co.uk). [21]

22 As conclusions can be reported that biogas sector needs in Italy can be like following summarized: a clearer and concrete procedure (above all administrative) to plan, start and running a biogas plant; possible use of digestate for agronomic purposes also when is co-digested animal manure and agricultural residues; increase efficiency of plants and introduce a kind of bonus to use the generated heat incentive on biomethane as fuels A consistent part of animals are located in small-medium recoveries ( heads each) and it would be important to introduce or force through incentives farmers to collaborate in some way (consortium) to build up and run common biogas plants. [22]