Hydrogen from Renewables Stored in Natural Gas

November 28, 2011 – Vol.16 No.37

HYDROGEN FROM RENEWABLES STORED IN NATURAL GAS.
by Bruce Mulliken, Green Energy News

I’ve been asked more than once,”What good are solar and wind energy if they only provide power part of the day? What about energy storage?”

I usually answer briefly, “Those are issues. They’re being worked on. In green energy, storage is the next big thing. Lots of companies are looking for an answer.”

Here in the U.S. there are any number battery energy storage systems already in place, connected to renewables too. But none of them are large enough to store all the power generated from a solar or wind plant. Batteries store electricity at a high cost. There will have to be a significant battery technology breakthrough, or some cleverness in battery design, for costs to drop dramatically. Low cost is necessary to make really large, grid-scale battery storage systems possible.

However, electricity storage might be much cheaper if electricity is transformed into another form of energy, then turned back into electricity again. For instance, pumped storage where water is pumped with electricity to high elevation ponds and released as needed to flow downhill using kinetic energy to spin hydroelectric generators, is already employed in number of locations around the world. Another electricity-to-another-energy is compressed air energy storage where, as the name suggests, air is compressed in underground caverns, then released as kinetic energy to generate electricity on demand.

A third technology that has been discussed and researched for years is to use renewables to generate hydrogen, store the gas, then use it as fuel for fuel cells or even combustion generators to make electricity.

While big tanks of potentially explosive hydrogen don’t sound very appealing, power and gas company E.ON of Germany is moving forward with an innovative plan: Use wind power to split water into hydrogen and oxygen through electrolysis, then blend that hydrogen into natural gas pipelines. (Solar energy could be used as well to power electrolysis equipment.)

I’ll let E.ON’s words describe the project in a press release:

E.ON examines options for storing wind power in the German gas grid

Power to Gas: innovative contribution to energy turnaround

E.ON is developing a pilot plant in Falkenhagen in the north east of Germany to convert power from wind energy into hydrogen which can then be stored in the country’s gas grid. The company is investing over EUR5 million ($6.7 million) on the pilot plant and further research into this innovative technology.

Using power from renewable energy sources, the plant will produce about 360 cubic meters (almost 13000 cubic feet) of hydrogen per hour from 2013 onwards through electrolysis. The hydrogen will be fed into the Ontras gas pipeline system and be used like normal natural gas. This makes the gas grid a storage system for power from weather-dependent renewables.

E.ON is committed to intensively testing the technology which huge potential. At present, up to 5 percent hydrogen can be added to the natural gas grid without any problems, and in the medium term experts expect up to 15 percent. This means that today’s entire renewable power output could be stored in the German gas grid. Demand for capacity on this scale will however only arise over the next decades, when most of generated power is coming from renewable energies.

"We need new storage capacities so that we can further increase the share of weather-dependent wind power in our generation portfolio in coming years. Using the existing gas infrastructure to store hydrogen is a promising approach in the long run, enabling us to combine our strengths as a power and gas company," said Professor Klaus-Dieter Maubach, member of the E.ON AG Board of Management responsible for Technology & Development.

If Germany increases the share of fluctuating wind and solar energy in power generation in the years ahead, the power available will at times exceed demand and bring the power grid to the limits of its capacity. E.ON is therefore investing in technology to store this excess power. At the moment, the focus is on enlarging the capacity of pumped-storage power stations. For instance, EON intends to extend the pumped-storage power station at Edersee in the federal state of Hesse and - together with its partners - build a new plant on the German-Austrian border.

On the surface, E.ON’s wind-to-hydrogen-to natural gas may not seem all that “green” since fossil based natural gas would likely be combusted to generate electricity or provide heat and hot water for homes, business and industry. However as much as 5 -15 percent of that natural gas would be from a clean renewable source (the wind) displacing 5 - 15 percent, or so, from “natural” fossil sources.

Natural gas, by the way is already a mixture of gases, but is mostly methane. The 15 percent maximum hydrogen blend may the maximum at which natural gas will combust normally without modification to equipment.

There are also ways to “green-up” natural gas: Blend carbon-neutral biogas to the natural gas mix or generate power using fuel cells. Depending on the fuel cell technology employed hydrogen can be extracted from natural gas, or in the case of solid oxide fuel cells natural gas can be fed directly. E.ON is already set to begin testing solid oxide fuel cells in a demonstration program using 105 BlueGEN combined heat and power units ordered from Ceramic Fuel Cells LTD (CFCL) of Australia.

Even coal fired power plant operators could get into the game: Any electricity generated but not sold could be used to make hydrogen. Since unsold electricity is adding emissions to the atmosphere without doing any productive work, producing hydrogen pumped into natural gas lines would put that coal electricity to work reducing the need for other energy sources.

Links:

E.ON
http://www.eon.com

Ceramic Fuel Cells LTD
http://www.cfcl.com.au