Storing green electricity as natural gas

[OKIsItJustMe]

http://www.fraunhofer.de/en/press/research-news/2010/04/green-electricity-storage-gas.jsp

Storing green electricity as natural gas

Press Release 5.05.2010

Renewable electricity can be transformed into a substitute for natural gas. Until now, electricity was generated from gas. Now, a German-Austrian cooperation wants to go in the opposite direction. In the future, these researchers and entrepreneurs would like to store surplus electricity – such as from wind power or solar energy – as climate-neutral methane, and store it in existing gas storage facilities and the natural gas network.

Throughout the world, electricity generation is based more and more on wind and solar energy. So far, the missing link for integrating renewable energy into the electricity supply is a smart power storage concept. Because when the wind is blowing powerfully, wind turbines generate more electricity than the power grid can absorb. Now, German researchers have succeeded in storing renewable electricity as natural gas. They convert the electricity into synthetic natural gas with the aid of a new process. 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. Currently, Solar Fuel Technology, the Austria-based partner company, is setting up the industrial implementation of the process. One advantage of the technology:it can use the existing natural gas infrastructure. A demonstrationsystem built on behalf of Solar Fuel in Stuttgart is already operating successfully. By 2012, a substantially larger system – in the double-digit megawatt range – is planned to be launched.

For the first time, the process of natural gas production combines the technology for hydrogen-electrolysis with methanisation. "Our demonstration system in Stuttgart separates water from surplus renewable energy using electrolysis. The result is hydrogen and oxygen," explains Dr. Michael Specht of ZSW. "A chemical reaction of hydrogen with carbon dioxide generates methane – and that is nothing other than natural gas, produced synthetically."

With the rapid expansion of renewable energies, the need for new storage technologies grows massively. This is of special interest for energy utilities and power companies. "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," explains Michael Specht: "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: It equals more than 200 terawatt hours – enough to satisfy consumption for several months. The power network has only a capacity of 0.04 terawatt hours by itself. The integration into the infrastructure is simple: The natural gas substitute can 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.

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. "The new concept is a game changer and a new significant element for the integration of renewable energies into a sustainable energy system," adds Sterner. The efficiency of converting power to gas equals more than 60 percent. "In our opinion, this is definitely better than a total loss," says Michael Specht. A total loss looms if, for instance, wind power has to be curtailed. The predominant storage facility to date – pumped hydro power plants – can only be expanded to a limited extent in Germany.

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 megawatt.

...

[NoNothing]

1. I mentioned this idea just yesterday

It's basically the same idea as the "hydrogen economy," except instead of using hydrogen - which is difficult and we have no infrastructure for - you use methane, which is easy and we already have a vast infrastructure for. Additionally, it lets you augment renewable sources of methane with natural gas if the demand outstrips the supply.

[kristopher]

2. This has potential for one phase of the transition to all renewables...

They specify 60% efficiency in "converting power to gas" but that is only part of the equation, however, since it has to be turned back into usable power. Presuming that end is also 60% efficient (overly optimistic IMO) them the final round trip efficiency is only 36%.

The infrastructure is there for both storage and burning of the methane, but the need exists for the infrastructure this team has developed, so there IS infrastructure costs involved.

The deciding factor will be how much other, more efficient storage will cost. Batteries can deliver round trip efficiencies in the 90% range, and pumped hydro, CAES and the new "rock battery" are between 70-80% round trip.

So as fuel costs rise with ratcheting down of carbon costs, there may be a window of opportunity where fuel costs are high enough to justify making some fuel from renewables, in the long run the low efficiency is going to be a killer.

[OKIsItJustMe]

3. "In our opinion, this is definitely better than a total loss,"

"A total loss looms if, for instance, wind power has to be curtailed."

http://environmentalresearchweb.org/blog/2010/04/beyond-baseload.html

...

NREL says that wind curtailment has been occurring frequently in regions ranging from Texas to the Midwest to California. For example it notes that at one point in 2004 nearly 14% of wind generation MWh had to be curtailed in Minnesota, though this fell to under 5% subsequently. It notes that, curtailment has also become a significant problem in Spain, Germany, and the Canadian province of Alberta – up to 60% in Germany in some cases, while in Spain, NREL notes ‘the amount of wind power curtailed as part of the congestion management program has increased steadily over the past two years’ . This is a terrible waste of potential green power…

NREL says that building additional transmission capacity is the most effective way to address wind curtailment, a point also made in its 2010 ‘EWITS’ study of eastern US options – which concluded that wind could replace coal and natural gas for 20–30% of the electricity used in the eastern two-thirds of the US by 2024. That would involve 225–330GW of wind capacity, and an expensive revamp of the power grid. However, like the earlier NREL study, it says that, with an improved grid, especially with long distance HVDC transmission allowing for balancing across the country, the amount of wasted wind energy, and the need for back-up, would decline.

...

[kristopher]

4. That only makes sense if you totally ignore what I wrote...

There is existing storage and there are existing turbines but there is no existing capacity to produce the methane they basing this on.

That means a capital outlay must be weighed against the productive capacity of the outlay.

Given the low efficiency that equation will only favor the use of this process for a brief time because higher efficiency technologies are available for electricity.

There is a more probable roll for it in producing fuel for heavy transportation. The value lies in energy density AND portability.

[OKIsItJustMe]

5. Silly Germans

They really should have contacted you...

[kristopher]

6. Really? How am I wrong?

If I'm wrong it should be fairly easy to explain why.

ETA: What I've added is completely consistent with what they say is their guiding idea - "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?"

[OKIsItJustMe]

7. Did I say you were wrong?

(Silly Germans...)