Just add hydrogen to remove CO2 from biogas
24-03-2016
Biogas from biomass gasification or fermentation contains considerable amounts of CO2. When using this to produce SNG, this needs to be removed, leading to a considerable energy penalty. But there is an alternative by adding hydrogen from electrolysis using renewable electricity. Then the CO2 and hydrogen react to produce methane, adding to the SNG production. An effect well known from thermodynamics but confirmed with experiments, with the prospect of a large impact.
Adding hydrogen can approximately double the SNG output of an SNG plant
VoltaChem co-initiator ECN has been investigating this option together with TUDelft and Hanze University Groningen in the EdGAR program and follow-up is aimed in the VoltaChem program. The existing technologies allow for the production of SNG that matches the specification for injection in existing infrastructure. The concept can thus be used to ‘store’ large amounts of renewable electricity in the natural gas grid. The impact for a typical biomass gasifier is significant. Adding hydrogen can approximately double the SNG output of an SNG plant. It was also shown that the quality of the SNG doesn’t fluctuate significantly when switching between CO2 removal and hydrogen addition, an important aspect for natural gas grid integration.
Use low-price electricity when production from renewable sources is high
The concept allows for making use of low-price electricity when production from renewable sources is high. To assess this effect, the fluctuation of the electricity price over the year has to be taken into account, which can be done using price duration curves. When combining these curves with the results from system modeling, the impact of the future electricity price variations, and operation strategies on process economics can be assessed. Detailed results of this study have been published in recent conferences and international journals.
Next steps
The next step is to design a cost effective, energy efficient and flexible power to renewable SNG conversion chain and to investigate different value chains that makes use of the biomass platform to introduce renewable SNG into the gas grid at large scale. The developed business cases will serve as a basis for a demonstration project and R&D program on novel electrolysers and integrated renewable SNG plant with an electrolyser.
Shared Innovation Program VoltaChem: call for participation
This research has been financed by a grant of the Energy Delta Gas Research (EDGaR) program. EDGaR is co-financed by the Northern Netherlands Provinces, the European Fund for Regional Development, the Ministry of Economic Affairs and the Province of Groningen. Building on the foundations laid down in the previous multi-partner research effort, the future development is intended to lead to a demonstration of the Power to Renewable SNG concept on-site with a commercial process. We invite interested parties from the industry, electricity sector and equipment/technology suppliers to discuss further opportunities for cooperation.
For more information please contact Yvonne van Delft, Innovation Manager VoltaChem.
Source: ECN
Share this page:
