How Heat Can Be Used To Store Renewable Energy

How Heat Can Be Used To Store Renewable Energy How can we store energy from intermittent renewable energy sources? Benny(I am empty)/ Flickr, CC BY

The effect that fossil fuels are having on the climate emergency is driving an international push to use low-carbon sources of energy. At the moment, the best options for producing low-carbon energy on a large scale are wind and solar power. But despite improvements over the last few years to both their performance and cost, a significant problem remains: the wind doesn’t always blow, and the sun doesn’t always shine. A power grid that relies on these fluctuating sources struggles to constantly match supply and demand, and so renewable energy sometimes goes to waste because it’s not produced when needed.

One of the main solutions to this problem is large-scale electricity storage technologies. These work by accumulating electricity when supply exceeds demand, then releasing it when the opposite happens. However, one issue with this method is that it involves enormous quantities of electricity.

Existing storage technologies like batteries wouldn’t be good for this kind of process, due to their high cost per unit energy. Currently, over 99% of large-scale electricity storage is handled by pumped hydro dams, which move water between two reservoirs through a pump or turbine to store or produce power. However, there are limits to how much more pumped hydro can be built due to its geographical requirements.

One promising storage option is pumped thermal electricity storage. This relatively new technology has been around for about ten years, and is currently being tested in pilot plants.

How Heat Can Be Used To Store Renewable Energy The conversion of electricity to heat happens in the central circuit, then stored in hot and cold tanks. Pau Farres Antunez, Author provided

Pumped thermal electricity storage works by turning electricity into heat using a large-scale heat pump. This heat is then stored in a hot material, such as water or gravel, inside an insulated tank. When needed, the heat is then turned back into electricity using a heat engine. These energy conversions are done with thermodynamic cycles, the same physical principles used to run refrigerators, car engines or thermal power plants.

Known technology

Pumped thermal electricity storage has many advantages. The conversion processes mostly rely on conventional technology and components (such as heat exchangers, compressors, turbines, and electrical generators) that are already widely used in the power and processing industries. This will shorten the time required to design and build pumped thermal electricity storage, even on a large scale.

The storage tanks can be filled with abundant and inexpensive materials such as gravel, molten salts or water. And, unlike batteries, these materials pose no threat to the environment. Large molten salt tanks have been successfully used for many years in concentrated solar power plants, which is a renewable energy technology that has seen rapid growth during the last decade. Concentrated solar power and pumped thermal electricity storage share many similarities, but while concentrated solar power plants produce energy by storing sunlight as heat (and then converting it to electricity), pumped thermal electricity storage plants store electricity that may come from any source – solar, wind or even nuclear energy, among others.

How Heat Can Be Used To Store Renewable Energy A concentrated solar power plant. National Renewable Energy Lab, CC BY-NC-ND

Easy to deploy and compact

Pumped thermal electricity storage plants can be installed anywhere, regardless of geography. They can also easily be scaled up to meet the grid’s storage needs. Other forms of bulk energy storage are limited by where they can be installed. For example, pumped hydro storage requires mountains and valleys where substantial water reservoirs can be built. Compressed air energy storage relies on large subterranean caverns.

Pumped thermal electricity storage has a higher energy density than pumped hydro dams (it can store more energy in a given volume). For example, ten times more electricity can be recovered from 1kg of water stored at 100°C, compared to 1kg of water stored at a height of 500 metres in a pumped hydro plant. This means that less space is required for a given amount of energy stored, so the environmental footprint of the plant is smaller.

How Heat Can Be Used To Store Renewable Energy Molten salt tanks for thermal energy storage in a concentrate solar power plant. Abengoa

Long life

The components of pumped thermal electricity storage typically last for decades. Batteries, on the other hand, degrade over time and need to be replaced every few years – most electric car batteries are typically only guaranteed for about five to eight years.

However, even though there are many things that make pumped thermal electricity storage well-suited for large-scale storage of renewable energy, it does have its downsides. Possibly the biggest disadvantage is its relatively modest efficiency – meaning how much electricity is returned during discharge, compared to how much was put in during charge. Most pumped thermal electricity storage systems aim for 50-70% efficiency, compared to 80-90% for lithium-ion batteries or 70-85% for pumped hydro storage.

But what arguably matters most is cost: the lower it is, the faster society can move towards a low carbon future. Pumped thermal electricity storage is expected to be competitive with other storage technologies – though this won’t be known for certain until the technology matures and is fully commercialised. As it stands, several organisations already have working, real-world prototypes. The sooner we test and start deploying pumped thermal electricity storage, the sooner we can use it to help transition to a low-carbon energy system.The Conversation

About The Author

Antoine Koen, PhD Candidate in Pumped Thermal Energy Storage, University of Cambridge and Pau Farres Antunez, Postdoctoral researcher in Energy Storage, University of Cambridge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

books_technology

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration

LATEST VIDEOS

The Great Climate Migration Has Begun
The Great Climate Migration Has Begun
by Super User
The climate crisis is forcing thousands around the world to flee as their homes become increasingly uninhabitable.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
by Toby Tyrrell
It took evolution 3 or 4 billion years to produce Homo sapiens. If the climate had completely failed just once in that…
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
by Brice Rea
The end of the last ice age, around 12,000 years ago, was characterised by a final cold phase called the Younger Dryas.…
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
by Frank Wesselingh and Matteo Lattuada
Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a…
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
by Richard Ernst
We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of…
Five Climate Disbeliefs: A Crash Course In Climate Misinformation
The Five Climate Disbeliefs: A Crash Course In Climate Misinformation
by John Cook
This video is a crash course in climate misinformation, summarizing the key arguments used to cast doubt on the reality…
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
by Julie Brigham-Grette and Steve Petsch
Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44…

LATEST ARTICLES

green energy2 3
Four Green Hydrogen Opportunities for the Midwest
by Christian Tae
To avert a climate crisis, the Midwest, like the rest of the country, will need to fully decarbonize its economy by…
ug83qrfw
Major Barrier to Demand Response Needs to End
by John Moore, On Earth
If federal regulators do the right thing, electricity customers across the Midwest may soon be able to earn money while…
trees to plant for climate2
Plant These Trees To Improve City Life
by Mike Williams-Rice
A new study establishes live oaks and American sycamores as champions among 17 “super trees” that will help make cities…
north sea sea bed
Why We Must Understand Seabed Geology To Harness The Winds
by Natasha Barlow, Associate Professor of Quaternary Environmental Change, University of Leeds
For any country blessed with easy access to the shallow and windy North Sea, offshore wind will be key to meeting net…
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
by Bart Johnson, Professor of Landscape Architecture, University of Oregon
A wildfire burning in hot, dry mountain forest swept through the Gold Rush town of Greenville, California, on Aug. 4,…
China Can Meet Energy and Climate Goals Capping Coal Power
China Can Meet Energy and Climate Goals Capping Coal Power
by Alvin Lin
At the Leader’s Climate Summit in April, Xi Jinping pledged that China will “strictly control coal-fired power…
Blue water surrounded by dead white grass
Map tracks 30 years of extreme snowmelt across US
by Mikayla Mace-Arizona
A new map of extreme snowmelt events over the last 30 years clarifies the processes that drive rapid melting.
A plane drops red fire retardant on to a forest fire as firefighters parked along a road look up into the orange sky
Model predicts 10-year burst of wildfire, then gradual decline
by Hannah Hickey-U. Washington
A look at the long-term future of wildfires predicts an initial roughly decade-long burst of wildfire activity,…

 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities

InnerSelf.comClimateImpactNews.com | InnerPower.net
MightyNatural.com | WholisticPolitics.com | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.