Scientists want to use mountains like batteries to store energy – ‘MGES’


 

Researchers propose a gravity-based system for long-term energy storage.

 

  • A new paper outlines using the the Mountain Gravity Energy Storage (or MGES) for long-term energy storage.
  • This approach can be particularly useful in remote, rural and island areas.
  • Gravity and hydropower can make this method a successful storage solution. 

Can we use mountains as gigantic batteries for long-term energy storage? Such is the premise of new research published in the journal Energy.

The particular focus of the study by Julian Hunt of IIASA (Austria-based International Institute for Applied Systems Analysis) and his colleagues is how to store energy in locations that have less energy demand and variable weather conditions that affect renewable energy sources.

The team looked at places like small islands and remote places that would need less than 20 megawatts of capacity for energy storage and proposed a way to use mountains to accomplish the task.

Hunt and his team want to use a system dubbed Mountain Gravity Energy Storage (or MGES). MGES employes cranes positioned on the edge of a steep mountain to move sand (or gravel) from a storage site at the bottom to a storage site at the top.

Like in a ski-lift, a motor/generator would transport the storage vessels, storing potential energy. Electricity is generated when the sand is lowered back from the upper site. 

 

How much energy is created? The system takes advantage of gravity, with the energy output being proportional to the sand’s mass, gravity and the height of the mountain. Some energy would be lost due in the loading and unloading process.

Hydropower can also be employed from any kind of mountainous water source, like river streams. When it’s available, water would be used to fill storage containers instead of sand or gravel, generating electricity in that fashion.

Utilizing the mountain, hydropower can be invoked from any height of the system, making it more flexible than usual hydropower, explains the press release from IIASA.

There are specific advantages to using sand, however, as Hunt explained:

“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,” said Hunt. “This makes it particularly interesting for dry regions.”

Energy From Mountains | Renewable Energy Solutions

Where would be the ideal places to install such a system? The researchers are thinking of locations with high mountains, like the Himalayas, Alps, and Rocky Mountains or islands like Hawaii, Cape Verde, Madeira, and the Pacific Islands that have mountainous terrains.

The scientists use the Molokai Island in Hawaii as an example in their paper, outlining how all of the island’s energy needs can be met with wind, solar, batteries and their MGES setup.

The MGES system.

“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 noted.

Check out the new study “Mountain Gravity Energy Storage: A new solution for closing the gap between existing short- and long-term storage technologies”.

Renewable to Clean Energy – Floating wind-to-hydrogen plan to heat millions of UK homes


Floating Wind to Hydrogen 25a74c7253afc70c79b50cf2f4f8919c

Project aiming to deploy 4GW, £12bn ‘green hydrogen’ array in the North Sea is backed by UK government

Floating offshore wind turbines far out in the North Sea will convert seawater to ‘green’ hydrogen that will be pumped ashore and used to heat millions of homes, under an ambitious plan just awarded UK government funding.

Deployment of a 4GW floating wind farm in the early 2030s at an estimated cost of £12bn ($14.8bn) could be the first step in the eventual replacement of natural gas by hydrogen in the UK energy system, claimed Kevin Kinsella, director of the Dolphyn project for consultancy ERM.

ERM – which is working on Dolphyn with the Tractebel unit of French energy giant Engie and offshore specialist ODE – plans to integrate hydrogen production technology into a 10MW floating wind turbine platform, enabling each unit to import seawater, convert it to hydrogen and export the gas via a pipeline.

“If you had 30 of those in the North Sea you could replace the natural gas requirement for the whole country.”

Deployment of hundreds of the floating platforms would be able to tap into the excellent wind resources far out in the North Sea, way beyond the depths accessible to fixed-bottom foundations, Kinsella told Recharge, estimating that a 4GW floating wind farm could produce enough hydrogen to heat 1.5 million homes.

“If you had 30 of those in the North Sea you could totally replace the natural gas requirement for the whole country, and be totally self-sufficient with hydrogen,” said Kinsella.

ERM in August received £427,000 under a UK government support plan for promising hydrogen technologies. That will be used to develop a prototype unit for deployment off Scotland using a 2MW turbine from MHI Vestas and the WindFloat platform, designed by floating wind specialist Principle Power and already successfully tested off Portugal, Kinsella added.

It plans to have the 2MW prototype ready for a final investment decision by 2021, at which point ERM hopes a major energy player – “an Engie or a BP or a Total” – will back the project to take it forward to deployment by 2023, with a full-scale 10MW version in the water in 2026.

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The Dolphyn team is integrating into the floating turbine platform the systems needed for water intake, desalination and conversion of water to hydrogen via proton exchange membrane (PEM) technology.

The gas will then be exported under pressure via a flexible riser, before joining the output of other turbines to be pumped to shore via a trunkline. Kinsella said the project team is talking to a “major oil company” about repurposing an existing pipeline for hydrogen export.

The floating wind-to-hydrogen turbines would be completely independent of the power grid – a major contributor to cost reduction Kinsella, said. “Once you get a long way offshore it’s the electrical infrastructure that dominates the costs.” They will be equipped with an on-board energy storage unit to make them self-sufficient, with the ability to restart the turbine from a standstill.

Generating ‘green hydrogen’ – completely produced via renewables – competitively at scale is one of the big challenges before it can assume a key role in the energy transition. Pilot green hydrogen projects currently operate at five to ten-times the cost of ‘grey’ hydrogen, which is produced using fossil fuels but is by far the cheapest existing option.

However, research group BloombergNEF recently projected an 80% fall in the cost of green hydrogen by 2030, opening the way for its widespread use as a carbon-free fuel.

ERM’s projections suggest a full-scale floating wind farm deployed in 2032 – by which time 15MW turbines may be used – could produce hydrogen at £1.15/kg ($1.41/kg). “This is comparable with the projected wholesale UK price of natural gas,” Kinsella claimed.

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Decarbonising heat and transport, as well as power supplies, are major challenges facing the UK as it seeks to become emissions ‘net-zero’ by 2050.

A 2018 report from the UK Committee on Climate Change said hydrogen could largely replace natural gas for heating into the 2030s, but questioned whether renewable generation could compete on cost with hydrogen produced using gas itself then subjected to carbon capture and storage.