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Storing surplus green energy as natural gas

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May 6, 2010

Existing infrastructure could be used to store surplus renewable electricity as synthetic ...

Existing infrastructure could be used to store surplus renewable electricity as synthetic natural gas (Image: Fletcher6 via Wikipedia Commons)

Throughout the world, electricity generation is based more and more on environmentally friendly wind and solar energy. The problem with such energy sources is their unreliability. Depending on the weather or time of day (or more specifically, night) the amount of electricity generated may be deficient or surplus to current requirements. Storing surplus energy in batteries for later use is one solution, but now researchers are developing a way to store surplus renewable electricity as natural gas.

Until now, electricity has been generated from gas. But a German-Austrian cooperation says it has found a way to go the other way. Their process involves transforming surplus electricity as climate-neutral methane, and storing it in existing gas storage facilities and the natural gas network.

The process was developed by the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), in cooperation with the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) and combines the technology of hydrogen-electrolysis with methanization. A demonstration system already operating successfully in Stuttgart separates water with surplus renewable energy using electrolysis to produce hydrogen and oxygen. A chemical reaction of hydrogen and carbon dioxide generates methane – which is nothing other than synthetically produced natural gas.

The researchers say that the rapid expansion of renewable energies results in the need for new storage technologies and they believe their process should be of special interest to energy utilities and power companies. The new technology aims at facilitating the integration of high shares of fluctuating power generation from renewable energies into the energy system. One goal is to structure the delivery of power from wind parks on a scheduled and regular basis.

"So far, we converted gas into electricity. Now we also think in the opposite direction, and convert electricity into ’real natural’ gas," explains Dr. Michael Sterner of Fraunhofer IWES, who is investigating engineering aspects and energy system analysis of the process. "Surplus wind and solar energy can be stored in this manner. During times of high wind speeds, wind turbines generate more power than is currently needed. This surplus energy is being more frequently reflected at the power exchange market through negative electricity prices." In such cases, the new technology could soon keep green electricity in stock as natural gas or renewable methane.

"Within the development of this technology, ZSW has been guided by two core issues," said Dr. Michael Specht of ZSW. "Which storage systems offer sufficient capacity for fluctuating renewable energies that depend on the wind and weather? And which storage systems can be integrated into the existing infrastructure the easiest?" The storage reservoir of the natural gas network extending through Germany is vast, equaling more than 200 terawatt hours – enough to satisfy consumption for several months. In comparison the power network has only a capacity of 0.04 terawatt hours by itself. The new process would allow natural gas substitute to be stored like conventional natural gas in the supply network, pipelines and storage systems, in order to drive natural gas cars or fire natural gas heating systems.

While the efficiency of converting power to gas isn’t perfect, equaling more than 60 percent, the team says it is definitely better than a total loss that may result if, for instance, wind power has to be curtailed.

In order to push the new energy conversion technology forward, the two German research institutes have joined together with the company Solar Fuel Technology of Salzburg. Starting in 2012, they intend to launch a system with a capacity of approximately 10 megawatts.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
11 Comments

Oil born war would be totaly over, soon.

Let us save the world then from water war.

Think please in involving communities in Energy Administration instead of favouring complex networked concerns, you know what that means.

Thank you all in the name of peace.

Facebook User
6th May, 2010 @ 07:57 am PDT

pure hybrid energy generation ??

is there a specific term for combining renewable energies ??

what a great innovation !!!

e bike-thekpv.com
6th May, 2010 @ 09:38 am PDT

Okay, now this is my order...I would like a hybrid that uses a natural gas engine, I would like to charge it using electrical energy that is generated by renewable sources, and then I would like to fill it right in my very own garage with natural gas generated by renewable sources, and I would like fries with that!

Paul Anthony
6th May, 2010 @ 10:01 am PDT

The amazing part of this article is that they plan to take hydrogen and oxygen and make a dirty fuel. All internal combustion engines, HVAC systems and cooking appliances can use hydrogen without the CO2. This is like turning Gold into lead. Solid hydrogen storage is safe and patented so no need to use dirty fuel storage vessels. We already pay a kings ransom for energy from the dumb grid. The reason cell phones and IPOD's catch fire is that they're hydrogen sponges. As the single most abundant element in the universe we already have all our energy needs available to us... it's in the air think fuel from air. With the right equipment we could go to McDonald's hook up our cars and be refueled in less than 8 minutes now that's a happy meal

John Graven
6th May, 2010 @ 10:55 am PDT

Methane is climate neutral at 20x the greenhouse power of CO2??????! If stored, OK, but there will be disasters like the current spill of oil in the Gulf of Mexico. If it is to be stored as a combustible gas why not as hydrogen?? Such storage would likely be short term and any leakage relatively benign.

MadMaxx
6th May, 2010 @ 11:20 am PDT

It seems apparent that a renewable energy farm supplying electricity for electrolysis would enable a hydrogen transportation fleet and methane to counter-produce electricity in a natural gas generating facility. However, how much carbon dioxide are we talking about, and where is that being utilized (flared off ?).

If it were possible to inject the carbon dioxide off-gas into a greenhouse where plants would up-convert it to oxygen, then this all makes sense. I've yet to see an energy process that uses carbon dioxide as a fuel source. Anyone...? Thoughts...?

JD Howell
6th May, 2010 @ 11:38 am PDT

The ignorance astounds. Why methane? Um, because you can store it cheaply and already have an existing infrastructure to utilize it? You can happily store useful amounts of it at room temperature in a car fuel tank for a long time.

Hydrogen, unless you're planning on launching a rocket or have figured out your very own Mr. Fusion, is a positively horrible energy storage medium. It has a low energy density. It loves to leak. It generally requires cryogenic or extremely high pressure storage to have any sort of practical footprint. Hydride storage? Yeah, no. Fuel from air? Um, that's kinda where this methane (or it's source atoms) comes from...

Plasma Junkie
6th May, 2010 @ 05:34 pm PDT

A sad joke!! Eff is very bad. Making H2 is at best 60% eff then methanization is maybe 70% eff then converting it back to electricity is 30-50% eff so the whole process is at best 20% eff. I'm sorry but that is not worth it.

Vs a battery which is 90% eff in most cases in and near 100% eff out.

But the notion that you need storage is not true as the grid already is made to handle it as demand is far more variable that wind or solar and the grid handles that easily. Even batteries only cost $10kwhr.yr easily paid for by charging at night and selling during peak power times. That this is a problem is propaganda made by the coal, oil and NG industries.

jerryd
6th May, 2010 @ 06:48 pm PDT

I have a simple energy storage idea, but I don't know how to market it. I would naturally like to profit from the idea. Let's be realistic!

windykites1
7th May, 2010 @ 07:03 am PDT

I'm with your Plasma Junkie.

I wish people would think before typing too.

At least they're reading... ;)

Craig Jennings
9th May, 2010 @ 08:39 pm PDT

Whatever happened to the plan to store H2 in graphite matrices? According to researchers at Northeastern Uni. they had layered graphite in a storage tank (at atmosphere) which H2 molecules adhered to. To release the H2 they heated the tank. Otherwise the H2 was bonded and couldn't 'leak'. Seems a better alternative to WW2 era 'Synth-Gas'.

Larry Pines
13th September, 2013 @ 01:39 am PDT
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