At Ecobuild 2014 Viessmann will be presenting its power-to-gas solution for addressing the peaks in power generation from weather-dependant renewable energy sources.
Viessmann, one of the world’s leading sustainable heating systems manufacturers, believes its model for storing excess power in the gas grid can pave the way for the UK’s successful transition from conventional to renewable fuels.
“Power-to-gas is a flexible and highly efficient method for converting excess renewable electricity and converting it into methane,” says Christian Engelke, Viessmann’s technical director.
“Excess electricity from wind farms or PV installation can be used to produce hydrogen. The Viessmann methanisation process creates 100 per cent methane which can then be transported and stored into the existing gas grid.
“We believe the methanisation of excess power will make it possible for such power-to-gas plants to contribute to at least five per cent of the UK’s gas requirement. This is also the plan in Germany where the goal is to provide 60 billion kWh of biomethane gas by 2020. This will release the burden of inconsistent supply on the electricity grid and conventional power stations.”
At present, surplus energy generated by the UK’s offshore wind farms cannot be stored or transported elsewhere, forcing the government to sometimes take the highly controversial step of paying wind farm operators to shut down.
Unless greater investment is made in technologies which address the way we heat our homes, most often using gas, says Viessmann, it is hard to see how the UK will be able to meet its emissions reduction goal of 80 per cent by 2050.
By contrast, the German natural gas grid has immense storage capacities. There the production of synthetic methane through power-to-gas technology is presenting real opportunities that Viessmann is already helping to develop.
The company’s pioneering research and development work in this field is being conducted by Viessmann Group company, MicrobEnergy. It has designed pilot installations at Viessmann’s headquarters in Allendorf, Germany, and at a municipal sewage plant that have demonstrated the practicality and efficiency of storing excess power in the gas grid.
Viessmann will be exhibiting information on the process at Ecobuild 2014, explaining the inherent suitability of its power to gas model to the UK due to the country’s heavy reliance on its own gas grid.
“Weather-dependent renewable energy sources, such as wind and the sun, inevitably lead to peaks in power generation and inconsistent supply,” adds Engelke. “As the proportion of renewables in the energy mix grows bigger, however, innovative storage technologies will become increasingly important.”
Power-to-gas involves converting excess power into hydrogen by means of electrolysis. This is followed by what is known as the methanisation stage, during which highly specialised microorganisms convert hydrogen and carbon directly into pure methane.
The microorganisms function at ambient pressure and temperature, and there are no special requirements regarding the purity of the source gases . The required CO2 can be sourced from industrial processes, biogas plants or even the surrounding air.
The synthetic methane obtained in this way can either be held in a gas storage facility and converted into electricity with a CHP unit as required, or can be injected directly into the natural gas grid.
Engelke continues: “The development of a green and sustainable gas is one of Viessmann’s key goals. If countries like the UK are to produce as much 80 per cent of their electricity from green, low-carbon renewable sources, then wind and solar clearly have to become the dominant components of the energy mix.
“In an energy market dominated by big central fossil-fuelled power plants, production can be planned and responsive. With increased dependence on renewables, production is subject to weather conditions and only able to meet energy demand at a local level and for short periods.
“A power-to-gas and storage solution means power generated by renewables can be stored and later released according to demand at a national level. Creating a link between the electricity grid and natural gas grids is therefore an important condition for the successful transition from conventional to renewable fuels.”