Turning Industrial “Waste” Heat Into Clean Electricity

New process could power 15M homes, says startup

Most of the world’s heat goes to waste. Heavy machinery generates heat, car engines generate heat, computers generate heat… 

An Israeli startup is developing a way to turn that heat into zero-emission electricity – benefiting both businesses, and the planet. 

Some of the biggest power stations have the technology to re-use waste heat, but they’re the exception, and they do it on a huge scale. For the vast majority of the world’s factories there has been no practical, affordable way to do so, until now.

Luminescent says its isothermal heat engine is the first of its kind. It claims it can generate zero-emission electricity from any source of heat – including waste heat – with double the efficiency, and half the cost of standard heat engines.

Other heat engines use an adiabatic process, in which waste heat is cooled, causing the gas to expand – hence the need for big heat engines. They then reuse it as water to power their energy production process.

By contrast, Luminescent uses a liquid process, which uses waste heat directly to spin turbines and fuel power generators to create electricity.   

The process is similar to carbonating water and needs a space no larger than two 40 ft shipping containers. 

Within the engine, a heat exchanger heats liquid within nozzles, and is then injected with bubbles of air. 

The bubbles heat and expand under the high temperature and pressure, until the mixture shoots out of the nozzles at a rapid pace. 

“Seventy per cent of the energy in the world is wasted as heat,” says Doron Tamir, Co-founder and CEO.

“It’s impossible to use it all, but you have the potential to generate hundreds of gigawatts as zero-emission electricity. But without a small, efficient, and low-cost heat engine, it’s actually impossible. And this is the problem we are hoping to solve.

“With our engine, you can take any source of heat – and turn it into energy.”

He says that if small-scale industries across the US installed his heat engine, they could generate 12 to 20 gigawatts of electricity – more than enough to supply the whole of Israel.

A single gigawatt is enough energy for 750,000 homes, so 20 gigawatts could power 15 million, without having to use any more sources of coal, oil, or natural gas. Fossil fuel reserves are expected to run out by the end of the century. 

“It’s a must for everyone to reduce carbon emissions,” says Tamir. “Imagine that a single company or factory needs 10 megawatts of electricity, and we can generate one megawatt or two megawatts of zero-emission electricity for them.

“If we generate some energy from them, at the end of the day they’ll need only eight megawatts, so we’ve actually reduced their emissions by 20 per cent.”

Energy prices have soared since Russia, Europe’s main supplier of natural gas, invaded Ukraine. In July, Russia cut exports of natural gas, in what the German government said was its attempt to hit back against Western sanctions. Rising demand due to heat waves and winter freezes across the continent has made things even worse. 

Luminescent’s solution could also help businesses, particularly in Europe, that receive annual ‘carbon credits’ representing emission rights equivalent to one tonne of carbon dioxide.

Those struggling to cut emissions can buy credits from low-emitting companies, creating an incentive to reduce carbon footprints.

“If we succeed, it would really be a revolution – because there are endless applications for this kind of project,” says Tamir.

He says the isothermal heat engine could be deployed everywhere – from factories and power stations, to data centers and compressor stations. All his customers would need to do is connect Luminescent’s heat engine to their source of heat.

“If you have just a small amount of heat, it’s not economical to generate zero emission electricity,” he says. 

“So what happens now is that you have the potential of hundreds of gigawatts of zero emission electricity that now just goes to the atmosphere.” 

The new process – at a third of the cost of existing technology – injects air bubbles into hot liquid rather than using gas. 

The bubbles expand, but not enough to necessitate the construction of a larger heat engine.  

“All of the engines that you know are based on gas, but our engine is based on liquid. The energy density of liquid is 1,000 times more than gas.”

“With liquid, everything can be smaller because the energy density is much higher, and because it takes up less space than a gas – so your valves can be smaller, your pipes can be smaller, really the entire generator as a whole,” he explains. 

Tamir, a veteran solar energy entrepreneur, says Luminescent is the first company to figure out how to create an isothermal heat engine.

In 2024, Luminescent will pilot its heat engine for the first time with two unnamed customers – an oil refinery, and a chemical factory. Both generate steam at the end of their production process, and have no efficient way of utilizing the waste heat.

And at the end of 2024, the company expects to launch a pilot within the US.

Luminescent was founded in 2020, and is based in Beit Yanai, an agricultural settlement in central Israel.

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