Getting into hot water – and making good use of it

Exergyn has set out to harvest electricity using just low-grade waste heat

Alan Healy, chief executive of Exergyn Ltd: says he expects the company to be manufacturing 1,600 water-powered engines a year by 2019

Alan Healy, chief executive of Exergyn Ltd: says he expects the company to be manufacturing 1,600 water-powered engines a year by 2019


It sounds almost too good to be true – an engine that runs on warm water. An Irish company though has come up with just such a machine, one that promises to be as good for the environment as it is for business.

The EU thinks it is a good idea too and has put €2.48 million into the development of the project over the coming two years via the Horizon 2020 research budget.

Investors, including Enterprise Ireland and the NDRC, have put in another €2 million or so and the company, Exergyn Ltd, hopes to be on the market with a commercial product by 2017.

The engine involved does not use fuel in the conventional sense; a supply of low-grade hot water is all it needs to make it go. It is based on the use of a “smart metal”, one that shrinks when exposed to hot water but then springs back to its original shape when it cools, says company chief executive Alan Healy.

The engine uses nitinol, a nickel-titanium alloy that has this “shape memory” characteristic, he adds. All it needs is waste heat available from any source, for example the hot water circulating in a car radiator or the radiator water from a fixed industrial engine.

The company, based in Glasnevin, Dublin, has been working on its engine technology since the company formed in 2011. “We are the world experts in what we are doing with shape memory alloys,” he says.

Exergyn is using it to generate electricity for use either on site or for sending into the grid. It harvests this energy using nothing more than low-grade waste heat.

Yet the shape memory alloy at the heart of Exergyn’s engine has been around for 50 years, says Healy. “It has been used in medical devices and in the Mars Rovers but no one used it for energy harvesting.”

High temperature

Hot water is an unwanted byproduct in many processes. It is difficult to reduce the heat and in many cases extra energy has to be put in to drive fans and other methods for cooling the water before dumping it.

The company’s engine can be connected directly to a stream of warm water at 90 degrees and will convert some of this heat energy into electricity. This drops the water down to about 70 degrees, potentially reducing the need to use fans or other cooling for the water stream.

The company was formed when Healy was looking for some engineering expertise to help him with a completely different project – a better three- pronged plug. It was more ergonomic, safer to use and could easily be branded by a manufacturer, he says.

In the process he ran into Barry Cullen, who had a PhD in thermodynamics, and Kevin O’Toole, an expert in specialist materials. They had been working at DIT Bolton Street on their water-powered engine.

The three did not pursue the new plug but did decide to go into business together and bring the engine to market.

“Effectively, it was an engine that could run on hot water and it had huge potential to lower carbon output. This appealed to me philosophically, but I also knew I had the business skills to join an early stage company,” he says.

Prototype followed prototype and the power output improved step by step. Funding rounds kept the company going and successes in the lab kept the show on the road.

“We were hitting all our milestones which was good for keeping the funding coming in,” Healy says.

More engineers and PhDs were hired to develop the engine and the company now employs 15 people, including the founders.

People encouraged them to look for EU funding and they applied last December. “They had this programme for SMEs and there was no need for lots of partners. It fitted perfectly.”

Their current engine has an output of about 10 kilowatts and this is energy that can be used on site or run back into the national grid.

It uses four nitinol rods which shrink by four centimetres and then expand back.

It does this, however, with huge force, with each rod exerting 60 tonnes of pressure. This provides a vertical thrust that works a hydraulic system that spins a generator to make electricity.

Renewable electricity

Healy sees a strong interconnection between biogas plant operators who use the gas to run industrial engines that produce electricity but also waste heat.

“We have made big plans. There is so much waste heat out there and in some way we don’t bank on legislation to make people change.”

The EU funding will help the company move the prototype device forward towards commercialisation and also scale-up manufacturing.

By early 2018, he expects Exergyn to be producing 30 units a month and then production is predicted to reach 1,600 units by mid-2019.