Adding gas from biomass to the gas grid - SGC

The laws and rules that provide the framework for the gas industry can be categorised into rulescontrolling:• Gas trade• Gas quality to end-user• Gas quality/quantity measurement• Gas requirement from safety aspects6.2.1 Gas tradeThe main legal document that provides the framework for the gas trade within the European Union,is the directive 98/30/EG [lit.33] from the European Commission that was approved by the EuropeanParliament on the 22 nd of June 1998. This directive is now being implemented in the nationallegislation in the member countries and should be integrated in the legislation by the year 2000. Thedirective is based on the general principle within the EU, i.e. there shall be no obstacles within theEU prohibiting a free movement of goods, persons, services or capital. The directive states that:• "The technical framework for operation of gas systems must be clear and provide operationcompatibility."• "Distribution companies must in no case discriminate users of the system, especially not infavour of own customers or suppliers to the system."• "Every distribution company shall provide any other distribution company with sufficientinformation in order to ascertain a safe and efficient operation of the interconnected systems."• "Access to the grid…shall be approved in accordance with national legislation. The legislationshall be fair and open. The following may be considered: a) The need to reject access wherediscrepancies between technical specifications in a reasonable way not may be overcome."The general intention of the directive 98/30/EG is to provide an open market that does notdiscriminate any supplier of gas. An interesting detail in the directive is a lack of definition of naturalgas. The directive not even states that natural gas should be a gas containing mainly methane. Thishas been added in some of the national legislation but natural gas is here normally only defined as"a gas containing mainly methane" which in most cases is also a definition that covers gas fromanaerobic digestion. The definition of natural gas is according to ISO [lit.34] “complex mixture ofhydrocarbons, primarily methane, but generally also including ethane, propane and higherhydrocarbons in much smaller amounts and some non-combustible gases, such as nitrogen andcarbon dioxide”. Note 4 in the standard states: "Natural gas consists predominantly of methane(mole fraction greater than 0,7 12 ) and has a superior calorific value normally within the range 30MJ/m 3 to 45 MJ/m 3 ". Syngas, for example obtained by thermal gasification of biomass, is therebyexcluded.12A mole fraction 0.7 equals closely a volume percentage of 70page: 61