The concept of storing renewable energy in stones has come one step closer to realisation with the construction of the GridScale demonstration plant. The plant will be the largest electricity storage facility in Denmark, with a capacity of 10 MWh.
AARHUS UNIVERSITY
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.
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What’s not to like? We are rapidly heading back towards the stone age, so we might as well adopt as much stone technology as we can absorb.
Yabba dabba do…Wilma!
I wonder why they didn’t call the project Sisyphus?
Next, bread from stones?
More stupidity from people who don’t understand thermodynamics.
If you’re going to do an energy storage system that stores heat, it’s far better to store the heat from a thermal plant (coal and nuclear work best, but even gas), and then use that heat at peak times (or when unreliables are failing to produce) to generate extra electricity.
If the system is large enough, then the way to sell it is that thermal plants can be ramped down to almost zero electricity production when the wind is blowing and the sun is shining (by storing the heat instead of using electricity), and when the sun is not shining and the wind is not blowing, these plants can overproduce their nominal capacity to pick up the slack.
That’s the way to do it, but producing electricity and then storing it as heat is just a dumb, dumb idea.
I don’t think that the Danes are stupid; they’re just trapped in a cult, and physics will have to teach them a hard lesson.
use this one wierd trick to make sunshine heat rocks
Nothing man does can come even remotely close to nature’s own energy storeage system: fossil fuels.
“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.”
So one tank will stay hot for maybe 4 days, so you then switch to the 2nd tank which by now is already cool?
Well. Not sure about everyone else on here, but I just think it’s an incredibly expensive and wasteful way to cook pizza.
“cheap and efficient alternative”
I’m curious HOW “efficient” – you pump heat into the stones and then extract that heat later for power (yes I understand about the hot/cold stones), ok – it seems to me there’s going to be a good bit of energy loss in that process. How much of the energy input can be extracted? Let’s not even consider storage over time: what percentage of the input can be extracted as useful energy immediately?
I notice that information isn’t present. Do they know the answer?
Seems to me this method was all the rage back in the 1950s-1960s, along with Buckminster Fuller structures. As new as that?
I have a sun room built on top of a gravel bunker by the previous owner to allegedly perform a similar task; build heat during the summer to radiate into the sunroom during cold weather; cool down the gravel during the winter to moderate when the sun room heats up.
Along with a massive brick wall to which the sunroom is attached.
Doesn’t work worth a dang.
Within a few days of serious winter, the sunroom requires heating. Cold air sinks and I worry about plants on bottom shelves freezing.
The sun room itself is not heated or cooled directly, house heat is shared through doors and windows.
Within a few days of late Spring or early summer, all coolness stored in the rock is gone.
A fan works best during all of the seasons
In winter, it takes 3-5 days for the wood stove to heat the brick wall mass, which does moderate winter temperatures in the sun room.
As far as the brick wall absorbing sunlight and radiating heat for hours, it appears to only work in summer.
Stop using the wood stove for a few days; a necessary function to clean out the ashes properly, and the wall cools down quickly.
The wood stove is massive yet does not have a grate for ashes to drop out below. I must spend time shoveling and sweeping, an unpleasant task if the stove is hot, so I let it cool.
The stove is a wonder.
Once the stove is lit it attracts the dog, cat and wife who are reluctant to leave an eight foot radius around the stove. A good charge of clean oak or black locust keeps the stove running easily for 8-10 hours.
Well, this idea will be a whale of a Sweat Lodge used by our ancient tribal friends. Or Finns and Swedes and the rest of us that like a hot steam sauna. Not a total waste.
Grid scale. One medium sized generator running for one hour. Or 5 wind turbines running for one hour in perfect conditions.
You would need 500 of these units to get a medium sized solar facility through the night. Each unit has some unknown amount of compressors and turbines. Imagine the maintenance on this.
I love these content-free articles. At least from the perspective of what would be of most relevance to an engineer or economist. What is the end to end efficiency (energy out vs energy in) and what is the overall cost per kwh stored? Couldn’t find anything on the net that talked to this so from my perspective this whole thing is the equivalent of vapourware . . .
Damming up the Baltic would probably work better and be far more reliable.
It’s not clear what the purpose of refrigerating the cold stones might be. If the hot stones can somehow be heated to 600 C by transforming the energy from a windmill, when it is not turning one can circulate high-pressure water over the hot stones to generate steam and drive a turbine to generate electricity. But what is the purpose of the cold stones?
Salute!
With new blog comment format I cannot tell if I am replying to a sub-poster or main dude or whatever, anyway…
The passive solar systems I am familiar with in the montains of Utah and Colorado work very well heating a reservoir of rocks or a liquid salt or even saltwater. The cooling part of the process is more complex. A very simple passive system can help heat a lotta water for your shower, and maybe some heat in the living room.
The sun energy on my deck heats up the living room at about 1 deg per 15 minutes just using the main window and door entrance. I regret not including a passive heating box outside the window and would have great heat whenever the sun hits it, which is many days a year, and more during the winter.
I do not have a lotta hope in heating rocks and then using the heat to drive turbines or anything. I place a lotta faith in venting my heated air or refrigerant to my storage pit and using it later. No cooling without lottsa help, but basic heating is very easy when living off the grid.
My garden hose gets up so hot that I have had it burst. But the idea of using wind turbines to heat a fluid and so forth just is not practical from an engineering aspect. Better to adapt the old Navajo and other native Americans’ architecture of the adobe walls for heat at night and cooler in the hot day.
Gums sends…
It doesn’t say how they are going to convert this relatively low grade heat into electricity. I hope not by boiling water. It takes ~1/7 th the energy to heat water from room temp to 100°C and the other 6/7ths of it to convert water at 100 to steam at 100! I guess you could just heat the water up to 100 and distribute it nationally to make tea without boiling it.
“The only real challenge with establishing 100 per cent renewable electricity supply”
Right. Umm. Nope. There would be a few other challenges, like mining all the iron, aluminium and copper required to make the vast number of wind turbines required, and making the steel and concrete and then endlessly replacing them as they fail.
As soon as the article started talking about “heat energy” I stopped reading. There’s no such thing.
“A megawatt hour (Mwh) is equal to 1,000 Kilowatt hours (Kwh). It is equal to 1,000 kilowatts of electricity used continuously for one hour. It is about equivalent to the amount of electricity used by about 330 homes during one hour.”
So that storage system will power 330 homes for 10 hours.
I keep looking for the diesel backup engine to run those turbines. The concept of heat storage and recapture completely escapes me which means it’s probably a unicorn project to capture eyeballs more than anything else.
Big deal. 10 Mega Watt hours is nothing close to grid size. It can only supply one average size all electric American home with electricity for a year. But yet, their cartoon shows four houses and some sort of commercial building.
Brilliant ! Take extremely high value and hugely usable energy (electricity) produced in the most expensive way (Wind Turbines / PV ) and turn it into low value high loss energy (heat) and store in stone filled tanks then somehow ? turn the heat back into electricity (steam turbine , hot/cold tanks?? ) transfer losses ???
I have an idea , why not instal 2 power supplies into homes , 1 would be the main 24 hour supply (normal) and the 2nd would be from wind and solar and solely used to heat a large hot water tank , store the excess electricity and establish reserves in every home and supply hot water at the same time . May not even require installation of new wiring into homes when a lot of homes are already supplied with 2 phase or 3 phase lines already . 1 phase for mains and the other for wind/solar .
Meanwhile in CHINA !
To put some context on the scale of the Chinese coal build out, that 38.4 Gigawatt addition in 2020 ALONE equates to one massive 1,000 Megawatt coal plant coming online every 9 days – week after week – for an entire year.
For Australian readers, compare those numbers to your much contested Hazelwood and Port Augusta plants so trivial in the global scale of things.
For the (faux) environmentalists check out the brand new $30 BILLION Haoji Railway… a line expressly built for the exclusive transport of 200 million tonnes per year of coal deliveries from the open pit coal mines of Inner Mongolia. (Online pics of the mines make for interesting viewing).
So when can we expect to see St. Greta standing at a podium in Bejing and giving a stern tongue lashing to Xi?
“a new innovation project”
What else could an ‘innovation’ project be but new? That’s what happens when you stop teaching Latin. People no longer know the meaning of words that have a Latin derivation. But then again, this project uses solar energy from the sun.
And whats the efficiency? THats the important figure we need to know because it directly impacts how many more solar and wind farms are needed. Already it is about 6 times capacity, whats it going to become, ten times? Thats a lot of wind and solar.
Correct me if I have got this wrong, and apologies if someone has already done the calc:
They are spending 4.7m EUR
for 10 mWh capacity
with a 3yr life.
At say 1 full discharge per week, 60% efficiency:
10 * 60% = 6 mWh per discharge * 156 wks = 936 mWh.
4.7/936 = 0.005 EUR per Wh = 5 EUR per kWh.
At full daily discharge (totally unrealistic?) = 0.71 EUR ($US0.86) per kWh.
That’s expensive. And it’s the cost to the utility, not to the end customer.