Some things are both counter-intuitive and extraordinary. To understand them, we really need to have a grasp of science. So I hope no one minds if I start with explaining a couple of things about science.
First off, gases behave according to certain physical laws. Compress a gas, and it gets hot by a predictable amount. Decompress it, and the precise opposite happens.
This is how a refrigerator works. First you compress a gas, making it hot. Then, without decompressing it, you cool it off in a set of coils. Then you allow it to decompress, making it really cold in coils hidden within the refrigerator. The gas is then cycled back to the compressor.
The second thing is that heat is everywhere in the universe. Nothing we know of is at absolute zero temperature. That means that everything has some heat in it. An air-source heat pump extracts heat from the cold outside air and moves it into the house.
Heat pumps, refrigerators, and air conditioners nearly all work pretty much the same way, using electrical energy to operate mechanical devices that move heat around. A heat pump takes heat from a cold place, making it colder, and puts it into another place, warming it up.
It happens that a resistance electric heater operates at just about 100% efficiency, delivering an amount of energy in heat that is equal to the electricity consumed by the unit (though this does not account for the loss of perhaps 65% of the energy used to generate the electricity in the first place). And this is where we come to the first of the counter-intuitive things I mentioned. Using the same amount of energy, a heat pump can deliver a good deal more heat than the 100% efficient resistance heater. This is because it is moving heat instead of making it. Avoiding calling things more than 100% efficient, we use a very slightly different concept and terminology to describe how well it does this, the coefficient of performance, or COP.
Now comes the exciting part. There is more than one way to drive a heat pump. Most of the heat pumps on the market use electrically driven compressors. A very few, however, use other means.
ThermoLift, a startup company in Stony Brook, New York, is in the last stretch of bringing a new kind of heat pump to market, and it has some really impressive features. ThermoLift aims to reduce the cost of heating and cooling by 30% to 50%, using equipment that promises to have costs on par with existing equipment.
Advanced building simulation by the National Renewable Energy Laboratory and testing by Oak Ridge National Laboratory (ORNL) are proving the concept. The Department of Energy (DOE) looked at over 300 technologies for heating and cooling and gave the ThermoLift heat pump the highest rating. It has been financed in part by grants from the DOE and the New York State Energy Research and Development Authority.
ThermoLift’s prototype heat pumps are powered primarily by combustion of natural gas, though other fuels could eventually be used in practice, including renewably produced hydrogen. The heat from combustion is captured in a chamber at the top of the unit containing helium. (We should note that no refrigerants are used, and helium is not a pollutant.) The helium and the heat are moved by a piston-like device called a “displacer” to a central, warm chamber from which it can be released into an area being heated. Meanwhile, a lower, cold chamber is drawing heat out of its own environment, and this heat is also pumped by a displacer into the central chamber.
The displacers are moved by the systems internal gas forces and synchronized by magnets, instead of motors and rods. Surprisingly, they are also the only two moving parts in the machine. This means that the heat pumps are very quiet and efficient. It also means they use nearly no electricity, possibly making them ideal for heating buildings that are not grid-tied.
In a laboratory, the cold chamber of the machine can be made colder than -150° F. The machine is actually extracting heat energy from an environment at that temperature and delivering it as what we perceive as heat. Because of this, ThermoLift’s heat pumps can heat a building when it is really, really cold outside. A COP of 1.3 is achieved by extracting heat from air that is at -13° F.
The first test units are being put to use. Twenty of them are being installed at government sites, including military installations, to be tested. And ThermoLift is getting ready for commercial release, possibly in 2020. We will watch for developments.
ThermoLift’s web site is www.tm-lift.com.
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