Virtual Biogas - Biogas-Upgrading and Grid-Injection

Status

ongoing

Summary

Biogas, which is produced during anaerobe digestion by micro-organisms, owns huge potential as sustainable energy supply for industry, households and even automotive purposes in the near future. The composition of this gas mixture can essentially be described as:

• Methane (CH4) 50 - 75%
• Carbon dioxide (CO2) 25 - 48%
• Hydrogen (H2) up to. 2%
• Traces of Hydrogen sulfide (H2S) and ammonia (NH3).

Biogas, when produced is saturated with water. Biogas can be used for several purposes: direct energetic usage (combustion), combined heat and power generation (gas engines, gas turbines), compression and usage as fuel, and the usage as a natural gas substitute after upgrading and compression.

For the usage as a natural gas substitute it is important to develop a cheap, efficient and robust technology to remove carbon dioxide, humidity and traces of ammonia and hydrogen sulphide for the specific requirements in rural areas.

Current technologies have certain disadvantages: using water absorption, for instance, it is difficult to reach the required methane concentration according to the Austrian gas quality directive G31 for the direct usage as a natural gas substitute. Investment costs are usually high and the specific energy consumption as well as the consumption of other resources (e.g. cooling water or fresh water for water scrubbers) are rather high.

It was the main goal of this project to realise a modern and efficient method for methane enrichment from biogas based on membrane separation technology (gaspermeation). The projected plant would be Austria's first industrial-scale upgrading plant with grid injection using this technology. Based on results and experiences of preceding research projects, a biogas upgrading plant with a capacity of 100 m³N/h (corresponding to 180 m³N/h raw biogas) has been designed, erected and commissioned mid 2007. The quality of the product gas is measured online and the compliance to the Austrian norms ÖVGW G31 and G33 is permanently monitored (upper heating value, carbon dioxide, oxygen, hydrogen sulfide, moisture, relative density). As a result, an annual amount of 800.000 m³N biomethane, representing a fully-fledged natural gas substitute, is injected to the public natural gas grid. During the winter months this gas is odorised and transported to the local gas grid. During the summer months a part of the gas is injected to the higher-rank regional gas grid (without odorisation) using a downstream compressor because of the limited gas consumption in the local grid. Using the public natural gas grid this biomethane is also transported ‘virtually' to public CNG-fuelling stations and used for automotive purposes.

The main advantages of the applied technique are the reduced methane-slip in the Offgas, lower operational and investment costs, and the very advantageous process dynamics. Due to the two-staged plant layout the methane content of the Offgas, which basically consists of carbon dioxide, can be reduced to a minimum. Moreover, this gas is transported back to the combined cycle gas engines of the biogas plant, mixed with the raw biogas stream and converted to heat and electrical power at the current plant site in Bruck/Leitha. As a result, the upgrading process owns zero methane emissions. Due to the higher carbon dioxide content at the intake side of the gas engine the anti-knock properties of the engine are improved. Another crucial advantage of the applied technique is the very compact and space-saving assembly. The whole upgrading plant with the named capacity including compression, fine-desulphurisation, measurement and control engineering and cooling water conditioning has been erected within a commercial 30-feet-container supplying enough space for possible plant enlargement.

The plant layout comprises plant operation without operating personnel and is fully automated. The simple and continuous character of the process allows a very stable controlled operation resulting in constant product gas qualities even under changing boundary conditions (quality and quantity of raw biogas). First analyses on electrical power consumption reveal high competitiveness and economical plant operation compared to existing processes for biogas-upgrading like absorption or adsorption.

During full operation of the plant all essential operational parameters are recorded and analysed. Based on this data the upgrading plant will permanently be optimised regarding performance and electrical power consumption. Presentations, scientific lectures and field-trips are organised to introduce the technology to the interested audience now and in the near future.

Project management

Ass.Prof. DI Dr. Michael HARASEK

Technische Universität Wien
Institut für Verfahrenstechnik Umwelttechnik und Technische Biowissenschaften

Project or cooperation partner

• Biogas Bruck/Leitha GmbH
  DI Gerhard DANZINGER
  Szallasweg 1
  2460 Bruck/Leitha
  Telefon: +43/664/260 34 03
  Fax: +43/2162/68100 DW 29
  E-Mail: biogas@energiepark.at
• AXIOM Angewandte Prozesstechnik GmbH
  Ing. Mag. Johannes SZIVACZ
  Unterwaltersdorferstraße 100 / 2
  2443 Deutsch Brodersdorf
  Telefon: +43/2254/76282
  Fax: +43/2254/74675
  E-Mail: office@axiom.at
• EVN AG
  DI Georg REITTER
  EVN Platz
  2344 Maria Enzersdorf
  Telefon: +43/2236/200-0
  Fax: +43/2236/200-2030
  E-Mail: georg.reitter@evn.at
• Technische Universität Wien
  Institut für Verfahrenstechnik, Umwelttechnik und Technische Biowissenschaften
  FG Fluiddynamische Simulation und Thermische Verfahrenstechnik
  Ass.Prof. DI Dr. Michael HARASEK
  Getreidemarkt 9/166
  1060 Wien
  Telefon: +43/1/58801-15925
  Fax: +43/1/58801-15999
  E-Mail: michael.harasek@tuwien.ac.at
• Energiepark Bruck/Leitha
  DI Michael HANNESSCHLÄGER
  Fischamender Straße 12
  2460 Bruck an der Leitha
  Telefon: +43/2162/68 100
  Fax: +43/2162/68 100-29
  Web: www.energiepark.at
  E-Mail: m.hannesschlaeger@energiepark.at
• OMV AG
• EVN AG
• Wienenergie Gasnetz GmbH