Solar’s New Competitor
Last week, Kate Galbraith wrote an article in the New York Times with the headline A Competitor Emerges for Solar Panels, which is somewhat nonsensical.
It’s about the small co-heat and power (C.H.P) electric generator and hot water systems available for residential homes. This technology is not just emerging. I wrote an article about these five or six years ago when they were first marketed in Japan.
The article suggests that you can sell your excess power back to the grid (which I could not confirm), like is done with solar panels, and I suspect that is why she thinks they compete with solar, but solar panels “generate” zero emission renewable energy. These C.H.P units “consume” a non-renewable GHG emitting fossil fuel. Cogeneration competes with other energy consuming devices like 95% efficient condensing forced air gas furnaces and heat pumps. It’s an apples to orange comparison when it comes to solar.
… it would often take homeowners 10 years to make back the cost [for a C.H.P. unit], in the form of lower utility bills … People are willing to pay a lot more money for solar panels than what a C.H.P. system would cost.
Fossil fuels are hard to beat when it comes to cost. Depending on where you live, the payback for solar hot water can be as short as four years or as long as eighteen. Solar photovoltaic has a much longer pay back period than solar hot water, but then again, it’s like paying extra for a hybrid car, in that some consumers want to use less fossil fuel, and are willing to pay extra to accomplish that. Think of solar as the ultimate high end appliance, like a fancy stove or refrigerator. If payback is all that matters, explain to me why people drive Cadillacs.
Let me explain what these systems are and how they work (anyone familiar with the concept can skip this paragraph). I’m doing this should Galbrith ever read this article because, as her headline suggests, she doesn’t seem to have a very good grasp of the concept.
You connect a gas motor, similar to the one on your lawnmower, to an alternator, similar to the one under your car’s hood. This combination is typically called a generator set similar to the ones you can buy at hour local Home Depot. Next, you wrap copper tubing, like the plumbing in your house, around the alternator and motor exhaust pipe and pump cold water through it. The waste heat from the motor and exhaust will heat the water which will be sent to a hot water tank. Instead of using gasoline to run the engine, you use natural gas or propane.
There are hot tub designs out there that are heated purely by the waste heat captured from the pump motor that has stainless steel tubing wrapped around it. There are no heating elements.
Small systems are gaining traction in Japan after the nuclear disaster last year, which led officials to order that nearly all of the country’s reactors be [temporarily] taken offline. Orders have “increased dramatically” since that event and are likely to rise even more sharply in the future, …The home systems in Japan tend to be much smaller than those in Germany or the United States …
High-end motor homes (the kind that rock and country music stars tend to travel in) have been using quiet built-in propane powered generators for decades, although nobody I know of bothered with capturing the waste heat. The Japanese apparently are turning to them because their government is failing to provide its citizens with adequate electrical power at affordable rates.
Several homes in my neighborhood have natural gas powered generators sitting in their backyards tied into their breaker panel in case of power outages. The systems being sold in Japan typically produce enough to power something like a toaster oven, or instead, some lights, laptop, router, and television, and enough waste heat for much of their hot water needs, but not for all home heating needs. And that is why you still need grid power and an additional heating system in addition to the C.H.P. unit.
You have to remain connected to the grid because these units can’t handle big loads like a clothes dryer, or stove, or fridge, or hair dryer and latte machine at the same time. And when your load is low, it sends power to the grid, spinning your meter backwards, assuming you need its waste heat. But if you are full up with hot water, it never comes on. You draw electricity from the grid.
There is no free lunch. These systems lower your electric bill but increase your natural gas bill. Ignoring the costs of the system, you should save money if your electric rates are high enough and your natural gas rates are low enough.
These systems are not typically designed for emergency power. They won’t work in a power outage (they have no battery to start the engine). You pay extra for that feature. And if you are concerned about GHG emissions, keep in mind that these systems burn a non-renewable fossil fuel, just like my 95% efficient gas furnace does.
As a consumer, you have to be careful. I have a neighbor who spent a lot of money to buy a hot water heater that has a heat pump on top of it. A heat pump grabs energy out of the surrounding air and sends it someplace, in this case, into a hot water heater. He didn’t realize that this acts like an air conditioner in the middle of winter, causing his furnace to run longer. There will be no net energy gain, no money saved.
In conclusion you will gamble $10,000 in hopes of saving $10,000 over a decade while burning a fossil fuel the whole time. If I’m going to gamble I’d rather do it with a solar hot water system, possibly combined with a heat pump like my neighbor, but located outside my home’s insulation envelope.