National Transport Library Research Database

Minskade metanemissioner och ökad biogasutvinning på Gryaabs avloppsreningsverk (Reduced methane emissions and improved biogas utilisation at Gryaab's WWTP)

  • Gryaab AB, Svenskt företag eller organisation, 556137-2177
Sponsors, duration, budget: Energimyndigheten, Gryaab AB ; 2010-03-01 -- 2012-06-30 ; 3500000 kronorRegistration number:
  • Energimyndigheten 2010000220
Subject(s): Abstract: På Ryaverkets avloppsreningsverk i Göteborg samlas rötresten efter rötningen upp i en rötslamsilo med en uppehållstid på ca 1,5 dygn innan den avvattnas. I rötslamsilon fortsätter biogasproduktionen, om än i betydligt mindre omfattning än i rötkamrarna. Eftersom silon idag är helt öppen avgår metangas till atmosfären. Projektet syftar till att bygga om rötslamsilon till en efterrötkammare med tak för att eliminera metanförlusterna och öka utvinningen av biogas. Tillbyggnaden innebär en stor klimatvinst och utgör ett bra exempel för andra reningsverk.Abstract: The biogas production from municipal waste water sludge at Ryaverket WWTP, Gothenburg, is 9.2 million Sm3/year, which corresponds to an energy production of 57 GWh. Ryaverket WWTP is operated by Gryaab AB, which sells the biogas to Göteborg Energi. The biogas is upgraded to biomethane and used as vehicle fuel to replace fossil fuels. The digestate from the biogas process at the WWTP is stored for 1,5 days in an open storage tank after the anaerobic digestion. The biological gasification process continues during this time, and biomethane is lost to the atmosphere. This emission does not only lead to a loss in biomethane production; since methane is a strong greenhouse gas, this methane emission is highly unwanted. This project aims at eliminating the methane emission and enable utilisation of the biogas which is produced in the tank by covering the residue storage tank with a gas-tight roof. The ordinary construction of residue storage tanks at WWTPs in Sweden is an uncovered tank, although covering of these tanks would give important environmental advantages with relatively small effort. The biomethane production in the storage tank is expected to be 1,3 GWh, which is enough to replace 146 000 L of gasoline. The leakage of methane from the storage tank is estimated to be 1950 tons of CO2 equivalents/year. If the biomethane produced in the storage tank is utilised as vehicle fuel instead, the reduced emissions due to replacement of fossil fuels are estimated to 350 tons of CO2/year, giving a total CO2 reduction of 2 300 tons yearly . An improved utilisation of resources by covering the residue storage tank will improve the competitiveness of biomethane as a vehicle fuel and is in agreement with a development towards higher standards regarding methane emissions. Measures against methane emissions and improved utilisation of residues from biogas production are prioritized in this program. Göteborgs Energi is the project owner and the legal body which hereby is applying for economical contribution.
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