Energy storage project in Utah described as world's largest of its kind

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Mitsubishi Hitachi Power Systems (MHPS) announced an ambitious energy storage project to develop what it claims will be the world's largest energy storage project of its kind, in Utah. Renewable hydrogen is at the core.

The project is dubbed "Advanced Clean Energy Storage" (ACES).

MHPS developed gas turbine technology that enables a mixture of and to produce with lower carbon emissions.

John Parnell in Forbes said their gas turbine for "can operate efficiently with a mixture of natural gas and ." He said that MHPS sketched out a technology roadmap that will eventually see a gas turbine using exclusively hydrogen.

MHPS is a global leader for heavy-duty gas turbines. The company said it will initially develop enough storage to serve the needs of 150,000 households for an entire year.

MHPS is not the only driver in this project, however. They are joined by Magnum Development. Magnum has below-ground technologies to store energy at utility scale.

According to POWER, the Magnum Salt Dome is a geologic formation tectonically developed from a bedded salt deposit. Seismic mapping suggests it measures "at least one mile thick and about three miles wide."

The news release said Magnum controls the only known 'Gulf Coast' style domal-quality salt formation in the western United States. The release said five salt caverns were in operation for liquid fuels storage.

The plan: to develop 1,000 megawatts of 100 percent clean energy storage. That number was as per the MHPS press release.

In an article by Sonal Patel in POWER, the author focused on clarifying what that 1,000 MW of renewable power actually represents. The project could store up 1,000 MW of renewable energy year-round. It could be provided to "variability-challenged" Western power markets.

Patel also said that, responding to a request for clarification about the 1,000-MW figure attributed to the facility, which will comprise both storage and , "MHPS said on May 31 ACES is still in the project scoping phase, and that the next step, which entails securing off-taker agreements for power, would determine the mix between renewable hydrogen, CAES, (SOFC), and flow batteries."

So, renewable hydrogen is not the only technology on tap. Three others are involved to serve the needs of 150,000 households for a year. The ACES initiative will deploy a total of four types of clean energy storage at utility scale. Joining renewable hydrogen are compressed air energy storage; large-scale flow batteries; and solid oxide fuel cells.

John Parnell in Forbes had more to say about the flow batteries. "The proposed Utah site will also feature flow batteries or flow machines as they are sometimes referred to. They behave like a battery but have longer discharge periods than lithium-based tech making them ideal for tasks beyond tweaking the grid."

"The technologies we are deploying will store electricity on time scales from seconds to seasons of the year," said Paul Browning, President and CEO of MHPS Americas.

Projects and proposals for energy storage are generally important topics. Forbes reminds readers of its benefits, for example, in the way that power can be pumped back into the grid at specific frequencies "to address any deviation from the optimal frequency," and its ability to limit the price impact of sudden peaks in demand on the network.

MIT Technology Review commented that "Finding ways to add vast amounts of cheap energy storage to electricity grids is crucial if clean but erratic renewable sources like wind and solar are to produce a growing share of total generation."

The project would be relying on hydrogen and compressed air stored deep underground. James Temple, senior editor for energy, MIT Technology Review, wrote that "Some energy observers raised questions about the project's viability, given the current economics of these technologies, neither of which is in wide use as a grid storage option."

Temple further said that "A growing number of researchers do believe hydrogen could eventually play an important role in grid-scale . The hope is that cheap surplus renewable electricity can be used to drive an 'electrolysis' process that splits water into oxygen and hydrogen. But currently, electrolyzers are quite expensive and hydrogen can be difficult to transport, among other challenges."

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Jun 03, 2019
150,000 households for an entire year.

1,000 MW of renewable energy year-round

Watts aren't energy - that figure tells exactly nothing.
150,000 households does not say whether that includes all energy or just electricity.

The average electricity consumption for a household in Utah is 744 kWh or 8.9 MWh per year, which makes the storage system 1.3 Terawatt-hours. That would be entirely unprecedented in the whole world - 10,000 times larger than Elon Musk's Megabattery in Australia.

Assuming their turbines achieve 35% thermal efficiency, that would need a capacity of 40 million kilograms of hydrogen, and 447 million cubic meters of space at atmospheric pressure.

Their plan appears to be to hollow out a salt deposit in Utah, which would have room for 10 billion cubic feet, or 283 million cubic meters of hydrogen or natural gas. This is close enough that the numbers seem plausible at least.

Where do they put the salt, though?

Jun 03, 2019
For the other number, 1,000 MW of energy year round could be interpreted as 1 GW for a year, which is 8.8 TWh - and that's not plausible: they don't have the space to store that much gas, and using the pressure of the gas in the cavern can only hold a fraction of the chemical energy it has, so hydrogen + CAES doesn't explain that figure.

As for the figures above, I forgot to count in the 35% which means you need 3x more hydrogen, but that's still roughly in the ballpark. You just have to increase pressure in the cavern to about 6 bars - which only makes sense because you can only get the gas out if it's above atmospheric pressure.

Jun 03, 2019
Though looking further into it, this is the exact same project they tried to sell back in 2009 for $8.8 billion to store natural gas, but failed to secure any customers.

It seems that now they've simply changed the marketing to renewable hydrogen plus pals, but they don't actually have those yet and the system is supposed to store natural gas to start with, then later introduce CAES, hydrogen, flow batteries etc.

Jun 03, 2019
Nothing about this proposal appears to be energy efficient except for the flow battery which has yet to be fully developed. Storing energy in the form of compressed air is particularly inefficient unless they can store the heat that is generated when the air is compressed and reuse it when the air is released.

Jun 04, 2019
Storing energy in the form of compressed air is particularly inefficient

It's efficient if you can compress the air without changing temperature - this occurs when the pressure container is large enough that it does not significantly heat up or cool down with compression/decompression.

Otherwise the gas heat up on compression and the heat is lost to the environment, and cools down on decompression and you lose pressure. In small scale systems, elaborate heat exchange systems must be used to recycle the heat back to maintain efficiency - in a large cavern, the change in pressure is so gradual that the temperature can even out inside the pressure chamber.

The efficiency is not extremely important as long as the output energy is cheap. Better to lose half than pay more to run natural gas turbines for the same.

Jun 05, 2019
what is 'renewable '' ? hydrogen

Jun 05, 2019
what is 'renewable '' ? hydrogen

Something which you can make again and again. Hydrogen burns to water, water is converted to hydrogen.

Jun 05, 2019
so how do you make it ? i know ! use energy [ from coal ]

Jun 20, 2019
so how do you make it ? i know ! use energy [ from coal ]

Or, from windmills, solar panels, wave generators...

The big problem with renewable energy is that the energy demand has a smaller variation than the supply of renewable power, and the latter is more random than the former, so when you scale the system up there's going to be very large portions of potential supply that can never be used directly because it does not coincide with when people actually need and use the energy.

For example, in Texas, the greatest output of wind power tends to coincide with the least demand during the night. As long as there's relatively little renewable power, it can be pushed around and "diluted" in the system, or sold out of the state, but the more you build the more difficult it is to sell - and the only point to have it becomes to collect federal subsidies even if you have to pay people to waste it somehow.

If you generate hydrogen, that's actual value for the money

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