Waste Heat Can Be Transformed Into Abundant Clean Electricity

By: Robin Fearon

Waste heat is a worldwide energy problem most people have probably never heard about. Every machine and power station, even renewable energy like wind and solar, creates heat that is simply lost in the atmosphere. Thankfully, scientists and engineers are devoted to capturing heat and transforming it into useful electricity.

April 28, 2022

There are huge gains to be made because around 70 percent of all fuel energy is lost when it converts to mechanical or electric energy. Now researchers at Penn State University have created a flexible thermoelectric generator that wraps around hot water or exhaust pipes, turning heat into electricity.

Flexible devices are more efficient because they attach to pipes in factories or on vehicles without having to be glued on like rigid devices. Then the thermoelectric materials turn temperature differences between the surface fixed to the pipe and the cooler outer surface into electric current – called the Seebeck effect.

“Think about an industrial plant with pipes hundreds of feet long,” said Shashank Priya, professor of materials science and engineering at Penn State. “If you can wrap these devices around an area that large, you could generate kilowatts of energy from wasted heat that’s normally just being thrown away.”



An enhanced geothermal system for thermoelectric power in Larderello, Italy.

Photo by: Atlantide Phototravel

Atlantide Phototravel

An enhanced geothermal system for thermoelectric power in Larderello, Italy.

Thermophotovoltaic devices are another promising way to use this waste heat. University of Michigan engineers have created a precisely machined thermophotovoltaic cell that could be used to generate electricity from surplus renewable power. The cells would use heat stored in molten salt and turn it into electricity on demand, in a form that is much cheaper than batteries, say its creators.

One of the factors crucial to any device’s thermoelectric efficiency is its material. If higher electrical energy can be created with smaller temperature differences, then the materials are said to have a high ZT value. And a new material created by scientists in Vienna has smashed the ZT value world record.



Engineers repair low-pressure steam turbines in a workshop.

Photo by: Monty Rakusen

Monty Rakusen

Engineers repair low-pressure steam turbines in a workshop.

Using a thin layer of iron, vanadium, tungsten, and aluminum applied to silicon crystal, scientists have doubled the previous best. The random distribution of atoms in their material slows down the way heat passes through it, making the thermoelectric effect last longer, able to power sensors and small computer processors.

Any new thermoelectric material has to have a distinct advantage, and research is identifying a number of promising contenders. Pyroelectric films are aimed at waste heat emitted at less than 100 degrees Celsius (212 F) and can generate electricity when a material is either heated or cooled.

Low-temperature generation includes computers and cars, making pyroelectrics particularly useful for squeezing more energy out of electronic systems.

Another relative advantage is inexpensive materials. More abundant elements like tin, selenium, and magnesium are cheap and abundant, with high ZT values when combined in the right way. Their use could lead to greener car engines and industrial furnaces.

And when it comes to personal electronics, thermoelectrics could eventually see off traditional charging hardware. Chinese researchers have built a wristband that gathers body heat to power a LED and may be able to power smartwatches or other mobile devices in the future.

Next Up

Doing Renewables Right

Having a “net-zero future” – where the world isn’t emitting excess carbon dioxide – can seem like a far-off pipe dream.With sea levels still rising, wildfires becoming more and more frequent – alongside other extreme weather like floods and storms – and biodiversity rapidly dwindling, it’s imperative we focus on expanding renewable energy across the world, increasing energy sources to help mitigate the impact that fossil fuels have on the climate.

How to Make Art and Alienate Pollution

Painting in a time of climate crisis.

Melting Glaciers Could Flood Society with Problems

Earth’s glaciers are both a precious resource and a fragile ecosystem that is disappearing quickly due to global warming. Scientists warn that glaciers will vanish from the mainland US within decades. And their rapid melting is dangerous to society and the natural systems we rely on.

Plucking CO2 from the Air Could Decarbonize Food, Fuel, and Fashion

Products made from carbon dioxide (CO2) captured from the atmosphere are part of a fast-growing trend to decarbonize nearly everything we use. Food, drink, fuel, and plastics can all be made using CO2 from the air. And recycling carbon could create a circular economy that vastly reduces pollution and waste.

How to Clean a River from the Sky

Multispectral cameras keep a watch on the polluted Ganges.

Thousands of Bacterial Enzymes Hold the Key to Plastic Pollution Clean-up

Scientists suggest that people ingest at least 50,000 plastic particles a year. Health issues linked to the way plastic chemicals act on the body include cancer and infertility. And investigations show that we are breathing in 100 times more microplastics in our homes than was previously thought. So what can help tackle plastic pollution?

There's a Biodiversity Crisis--Here's What You Need to Know

Despite the world slowing down during the pandemic and studies hailing the slowdown of pollution and positive benefits on the environment, there’s one thing that continued full throttle: the globe’s biodiversity crisis.

Polar Heatwaves Raise Alarm On Ice Melt and Sea Level Rise

Polar heatwaves in the Arctic and Antarctic have climate scientists concerned about the possibility of rapid climate breakdown. Soaring seasonal temperatures of 40 degrees Celsius above normal in Antarctica and more than 20 Celsius in the Arctic could be a sign of cataclysmic shifts in both regions.

Cutting Methane is Quickest Way to Limit Global Warming Before 2030

President Joe Biden has announced plans to tackle climate change by reducing emissions of the greenhouse gas methane by at least 30% by 2030. His pledge, agreed with the European Union, aims to raise ambitions for world leaders to combat global warming ahead of the critical COP26 climate summit in November.

Solar-Powered Robots are the Sustainable Answer to a Cleaner, Connected Planet

Solar energy is virtually unlimited and one of the cleanest forms of renewable power. So building machines driven by the sun makes perfect environmental sense.