Solar Energy
Denmark’s largest battery – one step closer to storing green power in stones
Pea sized stones heated to 600?C in large, insulated steel tanks are at the heart of a new innovation project aiming to make a breakthrough in the storage of intermittent wind and solar electricity.
The technology, which stores electrical energy as heat in stones, is called GridScale, and could become a cheap and efficient alternative to storing power from solar and wind in lithium-based batteries. While lithium batteries are only cost-effective for the supply of energy for short periods of up to four hours, a GridScale electricity storage system will cost effectively support electricity supply for longer periods – up to about a week.
“The only real challenge with establishing 100 per cent renewable electricity supply is that we can’t save the electricity generated during windy and sunny weather for use at a later time. Demand and production do not follow the same pattern. There are not yet commercial solutions to this problem, but we hope to be able to deliver this with our GridScale energy storage system,” says Henrik Stiesdal, founder of the climate technology company Stiesdal Storage Technologies, which is behind the technology.
In brief, the GridScale technology is about heating and cooling basalt crushed to tiny, pea-sized stones in one or more sets of insulated steel tanks. The storage facility is charged through a system of compressors and turbines, which pumps heat energy from one or more storage tanks filled with cool stones to a similar number of storage tanks filled with hot stones, when there is surplus power from wind or the sun.
This means the stones in the cold tanks become very cold, while they become very hot in the hot tanks; in fact up to 600oC. The heat can be stored in the stones for many days, and the number of sets of stone-filled tanks can be varied, depending on the length of storage time required.
When there is demand for electricity again, the process reverses, so the stones in the hot tanks become colder while they become warmer in the cold tanks. The system is based on an inexpensive storage material and mature, well-known technology for charging and discharging.
“Basalt is a cheap and sustainable material that can store large amounts of energy in small spaces, and that can withstand countless charges and discharges of the storage facility. We are now developing a prototype for the storage technology to demonstrate the way forward in solving the problem of storing renewable energy – one of the biggest challenges to the development of sustainable energy worldwide,” says Ole Alm, head of development at the energy group Andel, which is also part of the project.
The GridScale prototype will be the largest storage facility in the Danish electricity system, and a major challenge will be to make the storage flexibility available on the electricity markets in a way that provides the best possible value. Consequently, this will also be part of the project.
The precise location of the prototype storage facility has yet to be decided. However, it will definitely be in the eastern part of Denmark in south or west Zealand or on Lolland-Falster, where production from new large PV units in particular is growing faster than consumption can keep up.
The full name of the innovation project is ‘GridScale – cost-effective large-scale electricity storage’, and it will run for three years with a total budget of DKK 35 million (EUR 4.7 million). The project is being funded with DKK 21 million (EUR 2.8 million) from the Energy Technology Development and Demonstration Program (EUDP).
In addition to the companies Stiesdal and Andel, the partner group comprises Aarhus University (AU), the Technical University of Denmark (DTU), Welcon, BWSC (Burmeister Wain Scandinavian Contractor), Energi Danmark and Energy Cluster Denmark.
The partners will provide an energy system analysis and design optimisation for a stone storage facility as well as optimize the technical concepts and mature the GridScale technology to a ready-to-market scalable solution.
For example, the European energy system model developed by AU will be combined with the model for optimising turbines developed by DTU to gain insight into the potential role of the stone storage facility in a European context and to optimise the design:
“The transition to renewable energy changes the way the energy system works – simply because wind and solar energy are not necessarily produced when we need it. Therefore, we need to find out how the technical design can best be adapted to the energy system and in which countries and when in the green transition the technology has the greatest value. We will look to identify the combination of energy technologies that will provide the greatest value for the storage solution. I think that stone storage technology has a huge potential in many places around the world and could be of great advantage in the green transition,” says Associate Professor Gorm Bruun Andresen from the Department of Mechanical and Production Engineering at Aarhus University.
Research team achieves significant solar cell efficiency milestone
by Simon Mansfield
Sydney, Australia (SPX) May 26, 2024
A research team has created a tandem solar cell using antimony selenide as the bottom cell material and a hybrid perovskite material as the top cell, achieving over 20 percent power conversion efficiency. This advancement highlights antimony selenide’s potential for bottom cell applications.
Photovoltaic technology converts sunlight into electricity, offering a clean energy source. Scientists aim to enhance the efficiency of solar cells, achieving over 20 percent in conventional single-junction cells. Surpassing the Shockley-Queisser limit in these cells would be costly, but tandem solar cells can overcome this limit by stacking materials.
The team focused on antimony selenide for tandem cells, traditionally used in single-junction cells. “Antimony selenide is a suitable bottom cell material for tandem solar cells. However, because of the rarity of reported tandem solar cells using it as a bottom cell, little attention has been paid to its application. We assembled a tandem solar cell with high conversion efficiency using it as the bottom cell to demonstrate the potential of this material,” said Tao Chen, professor of Materials Science and Engineering at the University of Science and Technology of China.
Tandem cells absorb more sunlight than single-junction cells, converting more light into electricity. The team created perovskite/antimony selenide tandem cells with a transparent conducting electrode, optimizing the spectral response and achieving over 17 percent efficiency. By optimizing the antimony selenide bottom cell, they reached 7.58 percent efficiency.
The assembled four-terminal tandem cell achieved 20.58 percent efficiency, higher than independent subcells. The tandem cell is stable and uses nontoxic elements. “This work provides a new tandem device structure and demonstrates that antimony selenide is a promising absorber material for bottom cell applications in tandem solar cells,” said Chen.
The team aims to develop an integrated two-terminal tandem cell and further improve performance. “The high stability of antimony selenide provides great convenience for the preparation of two-terminal tandem solar cell, which means that it may have good results when paired with quite a few different types of top cell materials.”
Research Report:Sb2Se3 as a bottom cell material for efficient perovskite/Sb2Se3 tandem solar cells
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Flower or power? Campaigners fear lithium mine could kill rare plant
By Romain FONSEGRIVES
Rhyolite Ridge, United States (AFP) May 23, 2024
Delicate pink buds sway in the desert breeze, pregnant with yellow pompoms whose explosion will carpet the dusty corner of Nevada that is the only place on Earth where they exist.
Under their roots lie vast reserves of lithium, vital for the rechargeable electric car batteries that will reduce planet-heating pollution.
But campaigners fear the extraction of the precious metal could destroy the flower’s tiny habitat.
“This mine is going to cause extinction,” says Patrick Donnelly, an environmentalist who works at the Center for Biological Diversity, a non-governmental organization.
“They somehow claim that they’re not harming the (plant). But can you imagine if someone built an open-pit mine 200 feet from your house? Wouldn’t that affect your life profoundly?”
The plant in question is Tiehm’s buckwheat.
There are only around 20,000 known specimens, growing in a few very specific places on a total surface area equivalent to around five soccer fields.
In 2022, the wildflower was classified as endangered by US federal authorities, with mining cited as a major threat to its survival.
The plant and the lithium reserve on which it grows embody one of the key challenges and contradictions of the global climate struggle: how much damage can we inflict on the natural world as we seek to halt or reverse the problems we have already created?
– ‘Coexist’ –
Bernard Rowe, boss of Australian miner Ioneer, which holds the mineral rights to the area, says the lithium produced at Rhyolite Ridge “will be sufficient to provide batteries for about 370,000 vehicles” a year.
“We’ll do that year-on-year for 26 years,” he said.
Those nearly 10 million vehicles will go a long way towards meeting the goal President Joe Biden has set of cutting down the nation’s fleet of gas-guzzlers as a way to slash US production of planet-warming pollutants.
So-called zero-emission cars make up around 7.5 percent of new vehicle sales in the United States today — more than double the percentage just a few years earlier.
In California, the figure is more than 20 percent.
And while expansion in the sector has slowed, the category remains the fastest-growing, according to Kelley Blue Book.
And it’s not only in the United States: Global demand for lithium will increase five to seven times by 2030, according to the International Energy Agency.
The difficulty for US manufacturers is that much of the world’s lithium supply is dominated by strategic rival China, as well as Australia and Chile.
“The United States has very, very little domestic production,” said Rowe.
“So it’s important to develop a domestic supply chain to allow for that energy transition, and Rhyolite Ridge will be an integral part of that.”
Ioneer’s plans show that over the years the mine is in operation — it is projected to start producing lithium in late 2027 — around a fifth of the plant’s habitat will be directly affected.
But the company, which has spent $2.5 million researching the plant, says mining will not affect its survival; it is already growing well in greenhouses and biologists think it can be replanted.
“We’re very confident that the mine and Tiehm’s buckwheat can coexist,” Rowe said.
– ‘Greenwashing’ –
Donnelly counters that Ioneer is “basically greenwashing extinction.”
“They’re saying. ‘We’re going to save this plant,’ when actually they are going to send it to its doom,” he said.
Under the company’s plans, the strip mine will use hundreds of trucks, which Donnelly says will raise clouds of dust that will affect photosynthesis and harm the insects that pollinate the plants.
Ioneer says it has already planned mitigation methods, like dust curtains, and keeping the roads wet.
Still, Donnelly says, why not just move the mine? But Rowe counters that it’s not as simple as just digging somewhere else.
Ioneer has invested $170 million since 2016 to demonstrate the feasibility of this site, which it believes is one of the best around.
“Many of these other deposits haven’t had that amount of work, so they’re not viable alternatives to a project like this,” he said.
The US Department of Energy has offered Ioneer a $700 million loan for the project, if the Bureau of Land Management signs off on an operating permit.
Donnelly insists the issue is not just the future of one obscure wildflower, but rather just one example of large-scale biodiversity loss that is threatening millions of plants and animals.
“If we solve the climate crisis, but we drive everything extinct while we do it, we’re still going to lose our world,” he said.
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Tesla breaks ground on huge Shanghai battery plant
by AFP Staff Writers
Shanghai (AFP) May 23, 2024
Tesla broke ground on a massive battery factory in Shanghai on Thursday, Chinese state media reported, making it the US electric car giant’s second plant in the financial hub.
The project was announced last April after boss Elon Musk presented a vague but ambitious plan to investors to turbocharge growth.
However, the company last month reported a 55 percent drop in quarterly earnings, reflecting a decline in EV sales in an intensively competitive market.
The new Shanghai factory should make 10,000 units per year of Tesla’s Megapack batteries, state news agency Xinhua said.
Tesla says Megapacks are intended to store energy and stabilise supply for power grids, with each unit able to store more than three megawatt-hours of power.
The factory is expected to start mass production in 2025, state media said in May.
“I believe the new plant is a milestone for both Shanghai and Tesla,” the company’s vice president Tao Lin told Xinhua.
“In a more open environment, we can… supply the global market with large-scale energy-storage batteries manufactured in China.”
Musk has extensive business interests in China and is a fairly frequent visitor.
In April, he met Chinese Premier Li Qiang, and received a key security clearance for Tesla’s locally produced EVs.
Musk’s interests in China have long raised eyebrows in Washington — President Joe Biden has said in the past that his links to foreign countries were “worthy” of scrutiny.
The battery plant will be Tesla’s second in the Chinese city after its enormous Shanghai Gigafactory, which broke ground in 2019.
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