Mountain Gravity Energy Storage – Environmental Long-Term Energy Storage

Mountain Gravity Energy Storage

The storage of energy for long periods of time is subject to special challenges. An IIASA researcher proposes using a combination of Mountain Gravity Energy Storage (MGES) and hydropower as a solution for this issue. Credit: IIASA

The storage of energy for long periods of time is subject to special challenges. An IIASA researcher proposes using a combination of Mountain Gravity Energy Storage (MGES) and hydropower as a solution for this issue.

Batteries are rapidly becoming less expensive and might soon offer a cheap short-term solution to store energy for daily energy needs. However, the long-term storage capabilities of batteries, for example, in a yearly cycle, will not be economically viable. Although pumped-hydro storage (PHS) technologies are an economically feasible choice for long-term energy storage with large capacities – higher than 50 megawatts (MW) – it becomes expensive for locations where the demand for energy storage is often smaller than 20 MW with monthly or seasonal requirements, such as small islands and remote locations.

In a study published in the journal Energy on November 6, 2019,  IIASA researcher Julian Hunt and his colleagues propose MGES to close the gap between existing short- and long-term storage technologies. MGES constitutes of building cranes on the edge of a steep mountain with enough reach to transport sand (or gravel) from a storage site located at the bottom to a storage site at the top. A motor/generator moves storage vessels filled with sand from the bottom to the top, similar to a ski lift. During this process, potential energy is stored. Electricity is generated by lowering sand from the upper storage site back to the bottom. If there are river streams on the mountain, the MGES system can be combined with hydropower, where the water would be used to fill the storage vessels in periods of high availability instead of the sand or gravel, thus generating energy. MGES systems have the benefit that the water could be added at any height of the system, thereby increasing the possibility of catching water from different heights in the mountain, which is not possible in conventional hydropower.

“One of the benefits of this system is that sand is cheap and, unlike water, it does not evaporate – so you never lose potential energy and it can be reused innumerable times. This makes it particularly interesting for dry regions,” notes Hunt. “Additionally, PHS plants are limited to a height difference of 1,200 meters, due to very high hydraulic pressures. MGES plants could have height differences of more than 5,000 meters. Regions with high mountains, for example, the Himalayas, Alps, and Rocky Mountains, could therefore become important long-term energy storage hubs. Other interesting locations for MGES are islands, such as Hawaii, Cape Verde, Madeira, and the Pacific Islands with steep mountainous terrain.”

In the paper, the authors propose a future energy matrix for the Molokai Island in Hawaii, using only wind, solar, batteries, and MGES to supply the island’s energy demand. Hunt emphasizes that the MGES technology should not be used for peak generation or storing energy in daily cycles – instead it fills a gap in the market for locations with long-term storage. MGES systems can, for instance, store energy continuously for months and then generate power continuously for months or when there is water available for hydropower, while batteries deal with the daily storage cycles.

“It is important to note that the MGES technology does not replace any current energy storage options but rather opens up new ways of storing energy and harnessing untapped hydropower potential in regions with high mountains,” Hunt concludes.

Reference: “Mountain Gravity Energy Storage: A new solution for closing the gap between existing short- and long-term storage technologies” by Julian David Hunt, Behnam Zakeria Giacomo Falchetta, Andreas Nascimento, Yoshihide Wada and Keywan Riahi, 6 November 2019, Energy.
DOI: 10.1016/j.energy.2019.116419

6 Comments on "Mountain Gravity Energy Storage – Environmental Long-Term Energy Storage"

  1. gerald greenman | November 11, 2019 at 1:08 pm | Reply

    I suggested long time ago using retired locomotive with heavy trainload on a long slopes slowly winding its way up and releasing when necessary from a waiting position…it would descend when needed with a governor and a generator, No shovelling sand or pumping water,lots of US companies interested but they make the inventor take on too much by having to patent it first

    • Your idea sounds a lot more viable to me. Their idea is limited by how much weight the cable can support. Get building!

  2. gerald greenman | November 11, 2019 at 1:21 pm | Reply

    Message: Hi I am an 83 yr old exfarmer, But I feel the suburbs will be awash with useless batteries,I have just been watching a guy explaining his tunnel built into a mountain to store compressed gas which would be released when electricity generation is needed, also a man with barges lifting heavy weights up and down and then thres the planned snowy extravaganza I feel that my idea of building a railway track from used rails with a heavy locomotive with overhead cables ,loaded with ballast being raised up an incline and released when generation is needed would top that .here I live in OZ slopes and old railway equipment are always in abundance In the army we built tens of miles in a day so theres little investment apart from a generator and overhead cable,,,Experts would have to work out whether heavy weight and short distance or long would be the answer,also the slope ratio,,,and why not several lines kind regards
    Gerald Greenman

  3. Consider magnetic cylinders as a means of gravitational energy storage. They have potential energy in two forms: gravitational and electromagnetic.
    the cylinder is raised by running the track generator backwards.

  4. Transportation shifts toward battery storage will change the fundamental use patterns of electrical generation and use. Investment in high maintenance/low yeild power schemes like this will be limited.

  5. Nothing new here check petrol gas generator using the same system from the early 1900s

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