Standards for biomethane as vehicle fuel and for injection into the natural gas grid 22 March 2013 Arthur Wellinger European Biogas Association Deliverable 3.6 WG2 The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EACI nor the European Commission are responsible for any use that may be made of the information contained therein.
Table of contents Standards for biomethane as fuel and for injection...1 1. Starting position...3 2. The mandate and working groups of CEN TC408...4 3. Experts groups...5 4. Open points to be discussed...10 Page 2 of 2
Deliverable 3.6 2nd discussion paper as of March 2013-03-04 Development of standards 1. Starting position By end of 2012 in eleven European countries biogas was upgraded to biomethane. In nine countries thereof biomethane was injected into the grid. The longest experience has Sweden and Switzerland which started back in the early 90ies. All of the biomethane countries developed standards for injection (plus some more countries not injecting biomethane yet) however, a lot of differences could be found in fundamental aspects such as parameters and/or concentrations of compounds other than methane, with variations even up to a factor of 100 (i.e. for mandated oxygen levels). In the past years, there have been two EU funded projects aiming to develop common standards for biomethane injection in the natural gas grid. During the FP6 project Biogasmax, a proposal was developed 1 which wanted to find a compromise between stringent formulated parameters created by the national DSOs and parameters that could be achieved at reasonable prices and process energy. Another approach was made by Marcogaz, a technical association of the natural gas industry. They came close to an excellent solution until the different DSOs started to water down the proposal. The final proposal could not find common ground and was abandoned. During the discussion and formulation of the GGG project, an existing CEN groups could take over a mandate from the European Commission directly related to the topic, DG ENER s Mandate M/475. The GGG work programme (WP3/WG2) on biomethane parameters therefore planned a close collaboration with CEN if ever they would start their work but also keep contacts with IEA Bioenergy Task 37 and Biogasmax. Arthur Wellinger, project partner on behalf of EBA and WP3 leader is directly involved with IEA Bioenergy Task 37 work, acting in the agreement as Technical Coordinator and has therefore easy access to their data. The link to the (completed) Biogasmax project is also granted because Arthur Wellinger was directly involved as responsible project partner of the Swiss partner Berne. As such he was co-author of the recommendations for injection parameters. 1 www.biogasmax.eu/ Page 3 of 3
Shortly after the start of the GGG project the EC decided to allocate the above-mentioned mandate to a new CEN technical committee (CEN TC 408) to develop a standard for both, biomethane as a fuel and for injection, and this was the reason why the GGG consortium decided to fully collaborate with this group under formation. This was possible as two project partners, EBA and NGVA Europe had the right to participate in the TC as specialized European Associations. Specific contribution of GGG to the CEN TC408 commission: GreenGasGrids is represented in CEN TC408 through two of the consortium partners, i.e. EBA and NGVA Europe. Both partners represent the voice of the practice. EBA stands for the needs of biogas and upgrading plant operators as well as of the plant providers. EBA is supported within the CEN group by two representative of member associations acting within their country representation: The German Biogas Association (Claudius da Costa Gomez) and Club Biogaz (Christophe Mandereau). NGVA is the voice of the engine manufacturers that are in part also directly involved in CEN (Scania, Volkswagen). 2. The mandate and working groups of CEN TC408 After several discussions between CEN and the Commission, CEN was given the mandate to develop, as a first step: A European Standard for a quality specification for biomethane to be used as a fuel for vehicles; European deliverables such as Technical Specifications or European Norms for quality specification of biomethane to be injected into natural gas pipelines transporting either H-gas or L-gas. The CEN technical experts should consider whether it is possible and desirable for the proper functioning of the market to develop only one European Standard addressing the requirements of both applications. The European Standard on biomethane was to include no unnecessarily restrictive requirements, as long as the proper functioning in the intended applications could be guaranteed. Because the biomethane quality for vehicle fuel is closely related to the quality of natural gas which has not been defined so far the discussion cannot be separated into two CEN TCs. The work of CEN/TC 408 was therefore extended and addressed also the issue of CNG (Compressed Natural Gas) as a fuel, and blends of fossil CNG with biomethane under the TC umbrella. Page 4 of 4
Therefore, the new scope of CEN/TC 408 encompasses now both biomethane and natural gas as fuels and biomethane for injection into natural gas grids. The founding meeting of the CEN TC 408 took place on September 16, 2011 at Afnor in Paris. Erik Büthker from Holland was elected president while Charles Pierre Bazin de Caix from France was nominated secretary. Since then the group met eight times in total with the goal to formulate a draft proposal by fall 2013. In total 10 meetings are planned with additional focus group meetings, phone conferences and webinars. Responsible organisms of 17 Countries participate in CEN TC408: Austria (ASI), Belgium (NBN), Bulgaria (BDS), Czech Republic (UNMZ), Denmark (DS), Finland (SFS), France (AFNOR), Germany (DIN), Greece (ELOT), Italy (UNI), Latvia (LVS), Norway (SN), Slovenia (SIST), Slovakia (SUTN), Spain (AENOR), Sweden (SIS) and the United Kingdom (BSI). In addition there was an established liaison with seven EU organisations: Afecor, EBA, Farecogaz, GIE, Marcogaz, ENTSOG and NGVA Europe. Formal liaisons with other technical committees were established: CEN/TC 19 on Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin, CEN/TC 234 WG 11 on Gas infrastructure/ Gas quality and ISO/PC 252 on Natural gas fuelling stations for vehicles. A number of stakeholders participated occasionally during the meetings: Car manufacturers; grid operators; biomethane producers; fuel producers; natural gas suppliers and manufacturers of gas fuelling stations. The start was a little difficult for several reasons, the major being that the mandate was not as clearly formulated as should have been, especially concerning the job sharing or rather the definition of the responsibilities between TC 234/WG 11 - M 400 and TC 408 M 475. 3. Experts groups In order to allow an efficient work three internal expert groups were created within the framework of the TC 408: EG1: bio-content determination EG2: NG/biomethane as a fuel EG3: grid injection specification EG4: test methods Page 5 of 5
3.1 Expert Group 1 A topic which gave reason to long discussions was the expectation of the Commission as part of the mandate that a method should be developed or reported allowing the determination of biomethane at any place in the natural gas grid. It was expected that a C14 method would be applied. An expert group (EG1) was founded to explore the possibilities. After the first meeting, the expert group was in full agreement that such a method would not be feasible at reasonable costs. In an expert discussion paper it was highlighted that for full demonstration of biomethane various measurement points along a given grid would have to be installed to follow the biomethane flow continuously. Such equipment would cost in the order of 1.5 m Euro. Other methods to guarantee the mass (energy) balance between the injected and the removed biomethane like certificates (guarantees of origin) are proven, cost effective and even more precise. After several meetings with Kyriakos Maniatis from DG Energy it was decided to describe a method (as complicated and expensive as it is) for the potential case that it would have to be determined for legal or contractual reasons close to the point of injection. But at the same time an easy applicable control method should be introduced. 3.2 Expert Groups 2 and 3 It was soon realized that it would probably not be possible to define an equal standard for vehicle fuel and for grid injection. Therefore two subgroups have been founded. The vehicle fuel group (EG2) is mainly composed of car manufacturers and led by our project partner Jaime Alamo from NGVA Europe. The other expert group (EG3) on grid injection includes primarily the representatives of the national standardisation bodies, TSOs, gas utilities and the associations. The group is led by Jacques Dubost from GDF Suez. There is some interaction with EG2 in that the quality requirements of the vehicle fuel should not be higher as for natural gas because in next future the large amount of fuel will still be delivered by NG and not by biomethane. In essence, TC408 is dealing with three major cases: 1) Gas upgrading and grid injection with subsequent use in housing, industry or as a fuel; 2) Upgrading without injection and use it as a fuel either as a stand-alone fuel or as a blend e.g. with LNG; 3) Local production and local utilisation with very specific requirements (Fig.1) The challenge of the injection group is to find a common ground between all the different national parameters. All parameters to be proposed should therefore be based on sound measurements by standardized sampling and testing methods. A first list of parameters was proposed for the further discussion. An outline of the full table is given in Table 1. Page 6 of 6
Fig. 1 Different cases of fuel specifications by TC408 Page 7 of 7
Table 1: Major parameters for grid injection (Source EG3) In December 2011, EG2 came up with a first proposal for biofuel quality parameters that served for further discussions (Table 2). Page 8 of 8
Table 2. First proposal for parameters defining biomethane quality (Source EG2) The discussion on the lower heating value (LHV) has been narrowed down to 44MJ/kg corresponding to 95% methane. This is a little bit lower than the value in the German regulation DIN 51624 of 46 MJ/kg (Fig. 2). Page 9 of 9
Fig.2 LHV Relation for a binary mixture of CH 4 and CO 2 (Source: E.ON Ruhrgas) 4. Open points to be discussed A number of points are still open for discussion either because reliable data are still to be compiled or because the relevant data are not available yet and must be part of future research projects: - Sulphur - Siloxanes - Trace components that may (or can) have an effect on health - Exposure models for these trace components - Oxygen - Hydrogen - Methane number (parameter linked to the risk of knocking in engines, cf. octane number for liquid fuels) In the case of insecurity preliminary figures will be used in the standard that will subsequently be adapted. There is still dispute if these values will arbitrarily be set at a low value and weakened afterwards if possible or if they should be set at the upper limit of known band width and subsequently be reduced if necessary. Page 10 of 10
4.1 Hydrogen Sulphide ECE R110 sets a limit (for safety operation of Natural Gas Vehicles) of 23 mg/m 3 and the German DIN 51624 sets 7 mg/kg. The requirements for the limit of the H 2 S concentration are quite different depending on which client the participant is representing: Volkswagen requests a sulphur limit of max.10 ppm in CNG. Their argument is that petrol and diesel fuel already are at a limit of 10 ppm sulphur. The limit is dictated by the under-floor catalysts which cannot recover from high sulphur contents at low temperatures. Bosch promotes a North American study which proposes some 3,5-7 mg/kg limit due to the H 2 S combustion products sticking ICE valves. ACEA also asks for a limitation at 10ppm in fuel where as TC234/WG11 could accept 20mg/m 3 in the grid. The Netherlands have experience with a H2S content of natural gas delivered to the domestic market of close to zero and always lower than 5 mg/m3 whereas in Italy that H 2 S in their network code is a value below 6.6 mg/m3 (m3 at 1.01325 bar and 288 K). The biomethane producers promote a value not lower than 10ppm. The current discussions in TC 408 tend towards 5 to 10ppm. 4.2 Siloxanes Siloxanes might create serious problems in engine pistons (Fig.3) and especially in micro-turbines. When siloxanes are oxidized, silicium oxide is formed that covers surfaces leading to abrasion or even blocking of engines. Siloxanes are mainly a problem in biogas coming from landfills and sewage sludge digestion. Main sources are sanitary products (maquillage, tooth paste, shaving foams, etc.), foam from fire extinguishers, lubricants, etc. The German delegation reported, through its Bosch representative, of tests studying the impact on lambda sensors claiming the need for a total silicon content below 0,06 mg/kg. The main reported problem is linked to the effects of silicon glass layer covering the active electrodes of lambda sensors and creating malfunction in the signal to be transmitted, plus a potential deterioration of the catalytic active platinum-based electrodes Standard procedures in Austria and Switzerland are active carbon filters to remove the siloxanes. If low values have to be achieved, cooling down to -25 C is necessary. Page 11 of 11
Fig. 3 Silicium Oxyde (SiO 2 ) formation on engine pistons and piston blocks Several documents have been made available by different experts. Limits are depending on the application but the most strict ones for gas turbines and ICEs (ranging from 0,05 mg/nm3) up 2mg/Nm 3 for gas engines. There is still no agreed sampling and test method available yet. DNV KEMA has presented a project proposal to the EC for engine testing and GERG is willing to work in the sampling and test methods. 4.3 Water dew point Water content/water dew point: as both parameters are important and are also correlated (ISO 18453) CEN TC408 decided to limit only one of them, and preferably the dew point (Fig.4). Fig. 4 Water dew point in function of water content and pressure The proposal under discussion is to create a variable limit depending on the different climate zones: Page 12 of 12
Zone A: 0 0 C at 200 bar Zone B: -10 0 C at 200 bar Zone C: -20 0 C at 200 bar Zone D: -30 0 C at 200 bar The duty of the national regulators is to specify to which zone they belong 4.4 Methane number Methane Number is the measure of resistance of fuel gases to engine knock (detonation) and is assigned to a test fuel based upon operation in a knock testing unit at the same standard knock intensity. Pure methane is assigned as the knock resistant reference fuel with a methane number of 100. Pure hydrogen is used as the knock sensitive reference fuel with a methane number of 0. Gas Infrastructure Europe (GIE) is an association representing the sole interest of the infrastructure industry in the natural gas business such as Transmission System Operators. They are against the introduction of a methane number mainly for two reasons: 1. A Methane Number of 80 as recommended by Euromot (the European Association of Internal Combustion Engine Manufacturers) would endanger the Security of natural gas supply to the European market, limiting acceptable gas sources (e.g. from LNG). 2. Including the Methane Number in the European Standard requires an agreed and reliable method of determination and should incur minimum costs. The methane number ( M N ) is not a thermodynamic property of gas, so no Equation of State (EOS) can be used to calculate it. Moreover, there are different calculation methods available and the results are different depending on the method applied as listed below: - Linear Correlation method - Hydrogen/Carbon (H/C) ratio method - AVL method - AVL Inc. developed a method to calculate the methane number, based on experimental measures of different gas mixtures (up to C 4, H 2, CO 2 and H 2S ). Property software is available to purchase which uses proprietary algorithms to determine the Methane Number, but does not take into account all components. - E.ON- gas calculation - Calculations of various engine manufacturer methods Euromot asked for a Methane Number between 80 and 100 which would exclude the majority of available LNG from coming to Europe (Fig.5). The argument of Euromot is that a methane number below 80 would reduce the efficiency of modern gas engines (Fig.6). Page 13 of 13
Fig.6 Methane Number versus Wobbe index of imported LNG Fig. 6 Example of efficiency of gas engines (CHP) with different methane numbers A Methane Number of 80 would endanger the Security of natural gas supply to the European market, limiting acceptable gas sources. For example, Denmark has been supplied with natural gas with a methane number around 70 (AVL method) from the Danish part of the Page 14 of 14
North Sea for more than 20 years. The span of variation is typically from 65 to 75, all of which would require further processing or curtailment if the gas standard required a Methane Number above 80. Gassco has also expressed its concerns about the inclusion of the Methane Number since it may affect Norwegian gas exportations. As mentioned before, the inclusion of a Methane Number in the European Standard requires an agreed and reliable method of determination and should incur minimum costs. There is no commonly agreed Methane Number calculation method today: - The only methods to calculate Methane Number included in an international standard do not correctly predict the trend of the Methane Number when hydrogen is injected. - Current methods do not take into account the presence of hydrocarbons heavier than butane. - Some methods to calculate Methane Number (e.g. AVL) require the purchase or development of property software in order to be used effectively. ACEA and car industry is opting for a methane number of 70 (AVL method). This corresponds also to the engine test fuel. 4.5 Oxygen There is a large variety among the different countries in the allowed oxygen content from 0.1% up to 3% (Table 3) whereby the 0.1 correspond already to a 10 to 100 fold increase in France, the UK respectively in Spain. For the general NG grid specification, CEN/TC 234 is proposing to make it variable depending on aspects such as proximity to underground storages, though the limits are still to be discussed. For biomethane injection into the grid some preliminary values ranging between 0,1 and 2% have been proposed. Page 15 of 15
Table 3: Oxygen limits in the different countries Page 16 of 16