Tyler Hamilton works with cleantech companies from across Canada as an adviser with the non-profit MaRS Discovery District in Toronto.
When we burn fuel to power vehicles and machinery, drive industrial processes or generate electricity, most of the energy in this fuel is dumped into the atmosphere as heat.
In one 2016 study, German researchers estimated that 72 per cent of global primary energy consumption – that is, using coal, oil, natural gas and uranium as fuel – is lost as waste heat. Most of this heat is rated “low grade,” meaning it’s less than 100 C. It includes the heat emitted from data centre server farms and the warm air that flows out the back of your kitchen refrigerator or air conditioner.
Recovering low-grade heat in an economical way, particularly to produce large amounts of power, is tremendously difficult, but a Waterloo-based venture called Smarter Alloys appears to have found a novel way forward. The company’s approach lies in a seemingly magical alloy called nickel-titanium, which also goes by the names Ni-Ti or “nitinol.”
Nitinol is a shape-memory alloy, meaning that if a piece of nitinol is bent it will return to its original shape when heat is applied. Scientists have been fascinated by this unique property for decades, and in the 1970s, aerospace company McDonnell Douglas (which eventually became part of Boeing) developed a prototype device that took advantage of this heat-triggered mechanical movement to produce limited amounts of power.
Problem is, scientists back then didn’t know why nitinol behaved the way it did, meaning they couldn’t really manipulate the material in a way that explored its full potential. The alloy was also prohibitively expensive, killing any economic argument for pursing the concept.
But as many entrepreneurs know well, the future has a way of knocking down barriers that once stood in the way of past innovations. Enabling technologies are born. Costs fall. Markets demand change. Creative thinking and continued experimentation can lead to unexpected breakthroughs.
One such breakthrough came in 2008, when Ibraheem Khan, while working on his PhD at the University of Waterloo, discovered he could alter the behaviour of nitinol by using high-powered laser beams to “tune” its microstructure.
“We were able to program the alloy to make it react in a certain way when exposed to certain temperatures,” Dr. Khan explains , adding that with the approach, he could design a piece of nitinol to have more than a one-shape memory. “We can make materials function like machines.”
To illustrate his point, Dr. Khan hands me a piece of nitinol wire that looks like a straightened out paper clip. He asks me to warm it up by rubbing the wire in my palms, which I do. When I open my hands, I see that the wire is now in the shape of a maple leaf, bent perfectly in more than a dozen places.
“We call this a Multiple Memory Material,” he says.
When Dr. Khan founded Smarter Alloys in 2009 to develop commercial applications for the material, generating power from waste heating wasn’t on his radar. His initial focus was on high-end orthodontics, leading to a product called SmartArch. Made of nitinol wire, the SmartArch can be programmed to apply the right amount of force on each tooth. The tooth-moving forces along the wire are tuned to the temperature in a person’s mouth.
The wires, which became commercially available last year, work faster than conventional braces and require fewer orthodontic appointments. Treatment that might normally take 24 months can be reduced to as little as six months, Dr. Khan says.
Beyond creating perfect smiles, the applications of this technology are almost endless. Smarter Alloys is currently developing programmable stents for heart patients, lightweight and low-cost actuators for vehicles and airplanes, precision golf clubs and heat-activated sports apparel.
But the biggest prize, by far, is creating a heat engine that can finally take advantage of all the low-grade heat around us – even, one day, the latent heat that exists in our oceans. Dr. Khan estimates it as a trillion-dollar market opportunity, and in pursuit of that prize, he has created a subsidiary of Smarter Alloys called XtractEnergy.
Unlike other forms of electricity generation that depend on high-temperature, high-pressure steam to move a turbine, XtractEnergy’s heat engine – in its simplest form – uses a nitinol-based belt to turn a pulley that spins a generator.
The belt is tuned in different places so that it behaves a certain way when exposed to a low-grade heat source. When a tuned portion of the belt is submersed in warm water, it contracts, causing the belt to pull in one direction. When it leaves the water and relaxes, another portion is submerged, causing another contraction.
This process continues as long as one portion of the belt is always submerged in the water. When there is a consistent heat source, the belt will snake itself around the pulley, creating enough torque to spin a generator.
It’s efficient and also clean. Nitinol is non-toxic and entirely recyclable – the belts can be melted down and remade into new belts. It’s also an economical way of producing power with low-grade heat, partly because the cost of nitinol has fallen dramatically, thanks to scale production in China driven by its growing use in medical devices.
Most importantly, Smarter Alloys has perfected how to program the nitinol, turning otherwise simple pieces of wire into smart machines capable of great things. This intellectual property will give the company a big edge in the race to develop the world’s most efficient heat engine.