The first liquid heat engine can recycle 70% of the world’s waste heat into clean energy

As the world grapples with rising inflation, a cost-of-living crisis, climate change and more, it’s clear that the fossil-fueled status quo isn’t working. Fossil fuels may have seemed like the crutch we could depend on, allowing us to build, develop and evolve; however, the reality is that they are now causing the world to burn, swell and divide.

Fossil fuels currently account for approximately 81% of global energy production, with only 13% generated by renewables. By 2050, it is estimated that 90 percent of the world’s electricity must be derived from renewable energy to ensure human sustainability. As the harnessing of renewable energy sources gains traction, scientific minds and bold innovators are looking for ways to harness the unlimited amount of available energy without the huge environmental cost.

Israeli set up Luminescent is one of those innovators who breaks new ground in renewable energy. The company has developed the world’s first liquid-based isothermal heat engine that can efficiently and affordably recycle waste heat, the heat released as a by-product of any industrial process, thermal or mechanical. Globally, it is estimated that 70 percent of the world’s energy is waste heat; and has the potential to generate hundreds of gigawatts of zero-emission energy. The problem is that typical waste heat projects are less than 7 megawatts and are not economical, with a simple payback of more than seven years. Luminescent has found a way to convert this previously impractical renewable resource into zero-emission energy, while doubling efficiency and halving costs, without the use of rare minerals.

External heat engines (not internal combustion) used today operate adiabatically, meaning they do not allow heat transfer, using gases or vapors. This limitation, together with the low thermal density of the gases by volume, means that the engines are large, expensive and inefficient, with engines of less than 10 megawatts; and any generated power inaccessible to most power grids and generators. Instead, Luminescent’s engines allow liquid heat transfer through the isothermal expansion of air bubbles, meaning the temperature inside the engine remains the same, despite changes in volume and pressure.

“Our engine is the first engine that is based on liquid and is isothermal. Thanks to these two parameters, we can achieve a third of the cost compared to other existing technologies. And because of that, we can have two to three years of simple recovery.” Doron Tamirco-founder and CEO of Luminescent, explains a Sustainable brands® (SB).

Luminescent’s breakthrough in heat transfer enabled is the result of its innovative nozzle, which is integrated into the engine design. The nozzle allows the heat-transfer fluid (eg, hot water, hot oil, hot molten salt)—which has orders of magnitude of thermal energy per volume greater than any gas—to mix with air bubbles at pressure, which expand isothermally by transfer of kinetic energy.

“While the liquid is in the nozzle, we inject air bubbles, nitrogen bubbles or steam bubbles; these gases expand while suspended in the liquid because they attract heat from the surrounding liquid, maintaining the temperature gap.
Carmel Rothschildassociate professor at Israel Institute of Technology and the co-founder and CTO of Luminescent, told SB. “That’s it: the nozzle is designed so that when the bubbles expand, the liquid accelerates to maintain the fluid and its thrust-generating position.”

The process converts the initial heat and pressure inside the filter into kinetic energy.

“Generating electricity from the kinetic energy of liquids is extremely simple, similar to all hydroelectric systems,” explains Rotschild.

Luminescent engines can store up to 20 hours of energy, emit zero greenhouse gases, have 1,000 times more power density than conventional waste heat plants/engines, and have a comparable reduction in CAPEX. Using isothermal processes, the company has said it can transform any heat source from 100-550℃ into energy, doubling the efficiency of operations and providing up to 70 percent more energy than existing operations.

Luminescent is currently involved in two pilot schemes involving steam and gas pipelines, with players in the mining, manufacturing and energy industries eagerly awaiting the results. Luminescent recently received $7 million in seed round funding led by Grove Ventures‘General partner
Lior Handelsmanwith the participation of European Climate First VC Extantia Capital.

“Finding clean energy solutions is relevant to global markets and our planet, so we’ve decided to partner with Luminescent as they introduce their revolutionary isothermal engine that ingeniously recycles previously untapped waste heat,” says Handelsman .

The first commercial release of Luminescent is planned for later this year.

“In five years, we expect to be fully commercial in our first steel company market; and starting our second market, which is long-term storage: we have a fantastic long-term storage solution based on our engine. If we manage to tap into these two markets, it will be amazing,” says Tamir.