Biogas#Applications

As biomethane ( bio natural gas interchangeably ) methane is called, which is non-fossil origin, but has been produced from biogenic materials and is a component of biogas. To produce both natural and technical processes are eligible. Applies biomethane for the production of electricity and heat in cogeneration plants (CHP) or as fuel for vehicles. Prior to use, and distribution of produced biogas to biomethane must be processed and separated from other gas components.

• 4.1 injection into the natural gas grid
• 4.2 Use as a fuel

Formation

Methane can be produced both technically and naturally arise. Biomethane can be produced technically syngas from a biomass gasification. The biomethane produced in this way are referred to in English as synthetic natural gas.

However, is used more frequently present the so-called " Biogas". This results in the decomposition of organic material with exclusion of oxygen. Technical controls are taking place these processes in biogas plants. Largest Group of the biogas produced is methane (CH4) with 50-75 %. Deviated largely caused carbon dioxide (CO2 ), but also other gases such as N2, NH3, H2, H2S, O2, of volatile organic compounds, siloxanes and thiols. For the production of biogas in biogas plants are usually energy crops, manure and occasionally organic residues as substrates for use. But biomethane is also produced naturally as a component of methane in anoxic layers below the surface, bogs, swamps, areas of anaerobic sediments and rice fields, as well as uncontrolled landfills, slurry tanks or by emissions in animal husbandry.

2012 was taken into Zoerbig (Saxony- Anhalt), the first plant in operation, capable of producing biomethane from annually 20,000 tons of straw. The German Biomass Research Centre in Leipzig estimates the potential in Germany on 8-13 million tons, in Eastern Europe to 240 million tonnes, with 8 million tons or 2.5 gigawatts vividly the energy requirement of 4 million natural gas vehicles equivalent.

Preparation

Before being fed into the gas grid, the fermentation generated, saturated with water vapor raw gases be upgraded to natural gas quality. This gas processing mainly includes a substantial removal of water, carbon dioxide and hydrogen sulfide, as well as a conditioning and compaction. Biomethan thus can be used as a substitute for natural gas, in particular an adjustment of the calorific value ( Wobbe Index ) must occur. Depending on the technical and economic conditions different gas treatment processes are applied and combined.

The first steps of preparation and preliminary cleaning (dehumidification and desulfurization ) already take place in the biogas plant. The raw biogas produced contains after these steps, a methane content of an average of 50 to 60 % and a carbon dioxide content of 35% to 45%. The remainder is comprised of nitrogen, oxygen and other gases.

In the downstream purification to biomethane especially the part remaining carbon dioxide and traces of hydrogen sulfide by various physical or chemical methods ( absorption, adsorption or filtration ) is removed from the biogas and highly enriched methane. The resulting biomethane is compressed conditioned ( calorific value adjustment by means of LPG ( liquefied petroleum gas ) such as propane and butane or air) and subsequently be fed into the natural gas grid or to provide as a biofuel.

Furthermore, it must be via a gas quality measurement, the collection of important parameters of the injected gas ( calorific value, Wobbe index, density, etc.) and a determination of the amount of energy transferred ( billing calorific value ). The aim of these requirements to the gas quality is to provide the same quality of gas ( particularly in terms of calorific value ). Providing users and the settlement of the amounts of energy In addition, for safety reasons odorisation of the gas, so that the transparent and odorless gas can be detected by smell.

Possible processing steps are to:

• Desulfurization as hydrogen sulfide would lead to corrosion Grobentschwefelung Biologically with sulfur-oxidizing microorganisms
• Chemically with precipitating agents such as iron oxide, which bind S

• Adsorption bonding of water on silica or alumina
• Condensation by cooling

Feed

With regard to the quality of biogas, there are two standards for feed:

• Exchange gas (equivalent to natural gas quality, problem-free supply for pressure adjustment ) and
• Additional gas ( limited admixed; different composition and amount of energy to ground gas).

For the acquisition of biomethane into the natural gas network must correspond to the essential characteristics of the natural gas. Within the limits established by the DVGW worksheet G 260 fuel gas family " methane rich gases " and the L groups contained therein ("low" ) and H ( "high") must comply with the following values ​​biomethane:

In particular, within the H group is only possible as additional gas according upgraded biogas in the substantial carbon dioxide removal with a calorific value of about 10.6 kWh/Nm3. (Without enrichment as propane can be obtained by upgrading biogas no gas to produce higher calorific value than that of pure methane ( 11.06 kWh/Nm3 ). )

Dissemination and economy

Because of the level of investment needed biogas upgrading is valid only on a capacity of about 250 m3 to 500 m3 of biomethane per hour as economically. This corresponds to an electrical system output of 1 MW to 2 MW in direct from biogas in combined heat and power (CHP). In Germany, in April 2010, 32 plants for bio methane production with a total capacity of 21.333Nm3 ( standard cubic meters ) per hour in operation. Should Until the end of 2010 35 more plants connected to the grid, which are under construction or planning, so that the total capacity to 49 063 Nm ³ / h is expected to rise .. For 2011, 72 current systems nationwide are expected with a capacity of 54 093 Nm ³ / h. The stated goal of the federal government is that about 60 billion kWh biomethane produced per year in Germany in 2020. The equivalent capacity of approximately 1200-1800 biomethane plants and thus a new construction of at least 120 plants per year with a total investment in plant equipment 10 - € 12 billion. To provide the energy crops for biogas production, would by 2020 1.2 million hectares of arable land are available. To achieve this goal, the biogas production compared to 2007 would have to increase by 150%, provided that all of biogas is upgraded to biomethane. In power generation in CHP as about 4 % of electricity needs could be met.

Biomethane is - as biogas - especially subsidized under the Renewable Energy Act. A competitiveness against the substitution energy, natural gas is currently neither given nor foreseeable. Assuming the continuation of the classic oil price indexation of natural gas price, the Wirtschaftslichkeitsschwelle biomethane would be beyond ( unprecedented ) 230 USD / barrel of Brent crude oil. However, it is questionable whether the oil price linkage in the future - at least in previous form - still valid. On the domestic German natural gas market are increasingly used wholesale prices by, for example, the quotations at the Leipzig Energy Exchange EEX, which are generally below the oil-indexed prices.

Use

Biomethane is used for energy by either fed into the natural gas network ( biomethane ) or used as biofuel for natural gas vehicles. During the feeding plays an increasing importance is the use of biomethane as a fuel so far only a niche application dar. In Mecklenburg- Vorpommern the natural gas fuel is from 2011 added up to 10 percent bio- gas. In November 2010, Stadtwerke München (SWM ) had already begun to mix at their seven natural gas filling stations in the urban area 50 percent biomethane.

Feeding into the natural gas grid

When the gas is removed from the natural gas network to differentiate between natural gas and biomethane, if theoretically. An equivalent amount of the injected biomethane gas is withdrawn at any point of the network. Much of the energy fed into the natural gas grid biomethane is used in combined heat and power ( CHP) plants to produce electricity and heat production, since the CHP operators obtain increased current payments under the Renewable Energy Act. In addition, provide individual gas utility surcharge for the delivery of natural gas with biomethane share, as an environmentally friendly alternative to pure natural gas.

Use as a fuel

Biomethane can, like natural gas, used as fuel in automotive engines, but so far biogas is utilized rarely in this way. Vehicles that have been converted for the use of pure or bi-fuel natural gas can also be operated with biomethane. Unlike natural gas, biomethane is however virtually CO2 - neutral. With feeding biomethane into the natural gas network also is used also as a fuel gas containing a proportion of biomethane.

Overall, in Germany there are currently around 130 natural gas filling stations, where biofuel is offered 100 percent biomethane. Of which currently supplies 115 from biofuel producers Verbio.

Because of the high electrical efficiencies could be interesting in the future also the utilization of biogas in fuel cells. The high price of the fuel cells, which elaborate gas purification and in practical tests yet short life currently prevent widespread use of this technique.

Legal framework

The biogas feed is governed by numerous regulations, including in Germany, the Energy Act, the Gas Network Charges Ordinance and regulations of the DVGW. By since April 2008 valid Gas Network Access Ordinance ( GasNZV ) access of biomethane has been significantly simplified to the gas network. The regulation also specifies the objectives of the Federal Government for the development of biogas feed: 60 billion kWh of biogas and 2030 100 billion kWh of biogas to be fed into the gas grid by 2020. That would be about one- tenth of the electricity consumed in Germany in 2008, natural gas amount of 930 billion kWh.