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| Energy can be stored as sand or water for as long as needed. |
Store energy in the mountains
Storing energy for long periods of time is one of the biggest challenges for a permanent move to a renewable and environmentally friendly energy matrix.Solar energy, wind energy, wave energy, tidal energy and others are widely available, but they cannot maintain a constant supply of energy needed to meet the continuing demand of society.
Julian Hunt and colleagues from Austria, Denmark and Italy believe they have come up with a suitable solution for situations where current alternatives do not apply - such as underwater hydropower , flow batteries and various ways of " storing the wind ", for example. .
The concept was named MGES for "mountain gravity energy storage" - and can be combined with a hydroelectric dam.
Generate electricity with sand
MGES consists of placing cranes on the edge of a steep mountain with sufficient reach to carry sand (or gravel) from a base storage to a mountain top storage location. An engine / generator moves sand-filled storage containers from the bottom up, similar to a cable car.During this process, the potential energy is stored. Electricity is generated by lowering the sand from the upper storage location back to the base, harnessing the energy of the descending containers like a zip line.
If there are streams in the mountain, the MGES system can be hybridized with hydropower, where water would be used to fill storage containers in periods of high availability rather than sand or gravel, generating power.
MGES systems have the benefit that water can be added at any time in the system, thus increasing the possibility of capturing water from different heights on the mountain, which is not possible with conventional hydroelectric dams.
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Sand does not evaporate
"One of the benefits [of the MGES system] is that sand is cheap and, unlike water, doesn't evaporate - so you never lose potential energy, and it can be reused countless times. That makes it particularly interesting for dry regions."In addition, hydroelectric plants are limited to a height difference of 1,200 meters due to very high hydraulic pressures. MGES plants can have height differences of more than 5,000 meters.
"Regions with high mountains, for example the Himalayas, Alps and Rockies, could therefore become important long-term energy storage centers. Other interesting places for MGES are islands such as Hawaii, Cape Verde, Madeira and the Isles. Pacific, with steep mountain terrain, "detailed Hunt.
To test the concept, the team proposed a future energy matrix for Molokai Island in Hawaii, using only wind , solar , batteries and MGES to meet the island's energy demand.
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Store energy
Hunt emphasizes that MGES technology is not suitable for meeting peak demand or storing energy in daily cycles; Its main advantage is to fill a gap in the market as a long term energy storage location.MGES systems could, for example, store energy continuously for months and then generate electricity continuously for months or when water is available for hydropower, while batteries would handle daily storage cycles.
"It's important to note that MGES technology does not replace current energy storage options, but opens up new ways to store energy and harness untapped water potential in high mountain regions," said Hunt.
| Bibliography: Article: Mountain Gravity Energy Storage: A new solution for closing the gap between existing short- and long-term storage technologies Authors: Julian David Hunt, Behnam Zakeri, Giacomo Falchett, Andreas Nascimento, Yoshihide Wada, Keywan Riahi Journal: Nature Energy DOI: 10.1016 / j.energy.2019.116419 |
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Energy