Sandr is an industrial heat battery that stores heat between 500 and 1,000 degrees. In industry, they are dying for that heat. The system is so simple that the cost is far below that of lithium batteries, say the inventors.
"The whole industry is geared to low energy prices," says Niels Tiemessen, who co-founded Sandr Energy with Dennis Heijkoop. "As a result, saving energy was not a priority, but that time is really over. Capturing and reusing waste heat is becoming increasingly important, and that's what we're doing with Sandr."
Dennis Heijkoop and Niels Tiemessen
Pebbles or steel slag
In industry, 80 percent of energy consumption is for making heat, Niels continues. "But far too little is done with that right now. We store that waste heat, as well as heat made from excess electricity, in sand or pebbles. We can even use steel slag for it. That would be a nice use for material that nobody wants anymore." "And we've tried to keep our system as simple as possible," adds his associate Dennis. "That also keeps the cost lower than others."
Ingenious blow-in system
Basically, Sandr's system is just a big tank with a storage medium. But to achieve those high temperatures, more is needed. Energy is exchanged using air, which goes into the tank hot and comes out cold via an ingenious blow-in system. Reusing that heat is a matter of the reverse process: cold air goes in and then warm air comes out. For example, a baker can use it to store his residual heat, which would otherwise just be disposed of, to preheat his oven the next day. That way it needs to use much less energy to get up to temperature.
Energy on a barge
But there are more applications, Niels and Dennis think. "We can go up to a temperature of 1,000 degrees, so Sandr can be used in a lot of places in industry," Niels says. They also see opportunities in solar fields and wind farms. "Those have to scale down if they can't put their energy on the grid and so they lose hundreds of millions," Dennis states. "The dream is that we also convert that energy into heat and store it. If it can no longer be transported as electrical energy through the grid because of grid congestion, then you have to use it in another way. You can do that by storing it in lithium batteries. That now costs 200 euros per kWh. We are well below that at 20 euros. Moreover, you don't need environmentally harmful materials for it, only materials that are available here."
Then the batteries can be transported on a truck or barge. "Because they have the shape of a standard container. And industry desperately needs that heat. So you relieve the grid, it's sustainable and you don't have to turn off wind turbines and solar panels."
Not limited to 95 degrees
Dennis and Niels knew each other because they once worked for the same employer. Dennis had started developing a water-based heat battery for himself. The software he developed for that, they now use for Sandr. "That water battery is quite a good idea," says Dennis, "It's cheap to buy, and you can still provide heat up to 95 degrees. But you are limited to those 95 degrees, while industrial users demand much higher temperatures. Niels had all kinds of far-reaching ideas about storing heat in sand. When we met, we ended up with Sandr together."
The back of a beer mat
Sandr is not currently available. by the end of June, the proof of principle should be operational. "That's when the deadline expires for the grant we received with our implementation partner. We have all the stuff now, and we're going to put it together in the next month and a half. When that is done, and it is operational, it will be one of the largest heat storage facilities in the Netherlands, with a capacity of 6 mWh."
At that point, it is enough if they can store and release heat up to 600 degrees. The battery does not yet have to be connected to the processes of the company where it is located. "In the fall we will then integrate it," he says.
When we meet in early May, it's an exciting time for the two men. "What we once quickly calculated on the back of a beer mat, we are now actually building," Niels says. "In a shed we've been experimenting and to make it we've had to teach ourselves all kinds of disciplines."
Making speed
De implementatieparnter is a metalworking company with a powder coating line. Together, they received the grant to build the thermal storage facility. "That collaboration has many advantages," Niels emphasizes. "They have a huge gas consumption and at the same time a lot of solar panels. But because feeding it back yields less and less, they now really want to use that energy themselves. For that, they need that thermal storage.
"And for me, it's really a playground. It's a metal fabrication company, so they have tube welders, plate welders, press brakes, everything I need. I can come up with something and then it gets put together there. So then you can really pick up speed. Ideal, such a partner who also has the resources to make it"
