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Energy Storage

Published on October 3rd, 2013 | by Guest Contributor

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“Gravity Power” Energy Storage Plans in Germany

October 3rd, 2013 by  


Originally published on the Lenz Blog
by Karl-Friedrich Lenz

I am familiar with the idea of using large holes in the ground with a piston of mountain size moved hydraulically as an alternative to pumped water energy storage from Eduard Heindl’s concept of “Lageenergiespeicher” (Statusenergystorage, in a direct translation).

Instead of pointing to past posts on this blog on the concept, I’ll just go ahead and reprint them:

Moving Mountains for Energy Storage, July 1, 2013

TedX talk by Professor Heindl on his idea of storing energy:

I have blogged about this concept before, in November 2011. I like it. As Heindl explains in this talk, it is cheap (per kWh), has a high efficiency, and a low footprint.

The only problem is that there are none of these projects built yet. It may work, but it is still an unproven concept.

Eduard Heindl “Energiespeicher” blog, Nov. 17, 2011

At the Brave New Climate blog, there is a thread running on energy storage right now. One of the comments in that thread pointed to the “Energiespeicher” blog by German professor Eduard Heindl. I just added a permanent link to that blog (it is in German language).

“Energiespeicher” means energy storage, and professor Heindl has an interesting idea he calls “Lageenergiespeicher”, which might be translated as “Sysiphus” into English, or “statusenergystorage” for a more direct translation. He wants to cut out a VERY BIG ROCK out of a mountain and float it on water.

That would seem to get much more storage power per square meter of area used. A rock 500 meters in diameter and 1000 meters in depth would yield 1.7 TWh in storage capacity, using less than 1% of area and costing less than 10% compared to pumped hydro.

This was always an interesting concept. That’s because in contrast to pumped hydro, you don’t need mountains, and you need much less area, since most of the action is happening under the ground.

The problem until now was that Heindl promoted the idea, but there was no project actually implementing the concept in sight.

That has changed.

From this article by Wolfgang Kempkens at WirtschaftsWoche Green (in German) I learn that an American company called “Gravity Power” has plans to actually build three “Gravity Power Modules” in southern Germany. According to the article, they would have a combined capacity equal to the pumped hydro storage plant at Goldisthal in Eastern Germany.

According to Wikipedia, this is the largest hydro plant in Germany, with a capacity of 1,060 MW and the ability to store up to 8.5 GWh.

However, the area needed for this installation is 55 hectares for the upper basin alone. Over 200 hectares of forest was removed for building it, leading to strong opposition from environment protection groups, including a lawsuit that was settled for 3.58 million Euros.

In contrast, according to the article at WirtschaftsWoche Green, one “Gravity Power Module” needs only 12,000 m2 (1.2 hectare), or about two soccer fields, so three of them come at a cost of 3.6 hectares, compared to the 200 hectares needed for Goldisthal.

There is probably nothing to keep people from installing some solar panels and wind turbines on top of the shaft.

Readers of the “Silo saga” by Hugh Howey may find the concept attractive for other reasons.

“Gravity Power” has received patent US 8166760 B2 for their “System and Method of Storing Energy”. The application for that patent was filed on Feb 4, 2009. In contrast, Eduard Heindl says he got his idea in 2010, which would be later than this patent application.

Here is a 2011 Youtube record of a presentation by Gravity Power CEO Tom Mason about the technology:

He notes several advantages of this technology: They can build such a system in a couple of years, as opposed to the close to 10 years needed for a pumped hydro project. One reason is that permitting will be much easier, since it doesn’t use much land, has no emissions, and doesn’t use any water once the system is filled. Constructing the shaft takes only about a year, the longer time is needed to get the turbines delivered.

The system scales nicely, and they can install it wherever they can bore a large hole in the ground, which means they can go close to the existing grid or demand centers.

They can save about 10 percent of the cost by using abandoned mine shafts. Mason quoted a cost around $1000 a kW in his 2011 presentation, including 20 percent contingency and 15 percent profit. That compares to between $2,000 to $3,500 for pumped hydro projects if one starts from scratch, as opposed to using some existing reservoir.

They expect beating traditional pumped storage efficiency (which is between 75 and 80 percent), because they can work with constant water pressure, while pumped storage works with variable pressures.

Tom Mason sees Germany as a great opportunity, since replacing nuclear with renewable means Germany will need storage.

He also notes that this system is as flexible as possible, it can be turned on and off in a matter of seconds.


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