For seven years Ontario’s inventor Ian Marnoch has been developing a new kind of “heat engine” that he says can generate electricity more economically from lower-grade heat.  While that heat could come from anywhere: the ground, the sun, or an industrial waste process, geothermal needs a much better temperature spread to achieve wide ranging use.

In today’s circumstances the main player is big temperature differentials where steam can be made to drive a Rankine thermodynamic cycle – commonly thought of as a turbine connected to a generator.  There are other ways using such circulation fluids like ammonia and freon types that will work as well.  These are often binary systems where two steps are used to get to flowing and working heat.

All the Rankine based ideas rely on a fluid heating up, expanding and vaporizing to drive a turbine or Stirling engine that makes mechanical motion to generate electricity. The vapor is then cooled, condensing it back into a fluid that is recycled back through to repeat the process.

Ian Marnoch Shows His MTP Engine. Click image for more info.

Marnoch’s heat engine works using the principle a little differently. There is no phase change in the vaporization of the working fluids.  Marnoch’s system relies on dry pre-pressurized air that expands as it’s heated and contracts as it’s cooled.  That change in volume and pressure causes pistons to move that can generate electricity.

Marnoch isn’t the first to grasp this, but Marnoch has configured his machine such to get an edge over other technologies. He says his engine configuration can process heat much faster and at bigger volumes than Rankine machines.

“It can process about three times as much heat by value as an Organic Rankine machine of the same size,” says Marnoch, adding that his heat engine can be designed to be much smaller and, therefore, less expensive.  All good.

But the new advantage is it can tap into lower temperatures that aren’t viable with other technologies.  This technology doesn’t need the boiling ammonia up to boiling water and beyond levels of temperatures.

Here’s the key – all Marnoch’ cycle needs is the right temperature differential, the spread between the heat source and the heat sink.  That could be cool air, the water in well, a deep mine shaft or the temperature at the bottom of an old oil or natural gas well.

Lots of folks are going to be realizing the opportunities are huge in the natural environment.

The news is all Marnoch needs is a 20º C (38º F) or higher temperature spread and there’s potential to generate electricity. The system becomes more economical the wider the gap.  That’s a lot of territory and the geothermal value can be heat or a heat sink.

It’s quite an idea for mechanical energy from low temperature heat spreads.

Marnoch and a team of PhD students and professors at the University of Ontario Institute of Technology (UOIT) have been working to perfect his patented heat engine.  Funding from the Canadian and Ontario governments have supported development of the machine for the past five years with early seed money from The Ontario Power Authority and Ontario Centres of Excellence.  The latest prototype of the machine is at UOIT’s new Clean Energy Research Laboratory.

Marnoch is understandably eager to get the machine out in the field and tested in a real-world situation. Companies are lining up.  Canada’s St. Marys Cement is exploring using the Marnoch engine to generate electricity from the waste heat of its Bowmanville cement plant.  Martin Vroegh, environmental manager at St Marys said, “It is in very early discussions but we are very enthusiastic about the potential and what this can mean for industries with large volumes of low-grade waste heat.”

Marnoch knows the current situation saying, “We just need to get out there and prove it works.”

With essentially any temp range where better than 20º C or 38º F can be had on the cheap money can be made or savings held or costs can be recovered.  Some folks are going to sit up and notice and Marnoch’s machine will get market legs.  Next up after field demonstrations is going to be working to more models and mass market pricing.

Go Marnoch!


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