This commentary is by Norm Etkind, a resident of Woodbury. He worked in the energy field and has certifications from the Association of Energy Engineers in energy management, sustainable development, building commissioning and energy auditing.
I heard a radio ad recently that said you can heat your house using solar electricity and heat pumps. Consider: There is little available sun in the winter and, as the temperature drops, it reduces the amount of heat that heat pumps can efficiently extract from the outside air.
All told, you will not be heating your house with air source heat pumps powered by solar electricity to any appreciable extent.
As Vermont wrestles with how to meet the challenge of climate change, it is important to understand the underlying science and technologies we may choose to use. This is difficult, with so many interested parties promoting their agendas. The information dispensed is often driven by altruism, honest misunderstanding, capitalism and, of course, politics.
Don’t get me wrong. Solar electricity is a technological marvel — the panels sit in the sun and, with no moving parts, generate high-quality electricity. Similarly, cold-climate heat pumps are a significant improvement in that technology. Many people can and do enjoy using them for heat and air conditioning.
To explain further: In winter, the days are short, the sun angle is low, the solar panels are often covered with snow, and there are a lot of cloudy days. The amount of available sunshine for generating electricity is diminished.
On the other side of the equation, heat pumps work very efficiently at cool temperatures. However, because they literally extract heat from the air, when there is less heat available, they need to work harder. When it’s cold enough, they stop working entirely. Along the way, at low temperatures, they are no more efficient than electric baseboard or plug-in heaters.
Large-scale use of air source heat pumps will create huge issues with peak electrical demand during winter evenings when electrical demand is highest and no solar contribution is available.
I heard Liz Miller’s testimony on behalf of Green Mountain Power recently. She said that Green Mountain Power can supply power to an additional 200,000 heat-pump-heated homes. “It’s what we do,” she said. Yes, it is what they do. They are happy to install many millions of dollars’ worth of line upgrades, new service drops and new transformers. In addition, they can install many additional millions of dollars’ worth of batteries and mechanisms to help manage the peak loads that heat pumps will generate. Green Mountain Power is allowed a guaranteed profit from that work. All of its ratepayers will pick up the tab.
Because you can’t heat your house to any appreciable extent with solar electricity in the winter, and because heating demand will exceed local sources of electricity when coldest, you will be heating your building primarily using electrical grid power for your heat pumps. During cold days, the grid will get constrained due to both the increased demand from heat pumps and increased demand needed to charge electric vehicles that utilize electric heaters. The ISO-New England-supplied grid electricity, during periods of heavy winter use, is comprised mainly of nuclear and fossil fuel sources.
A great way to ameliorate this problem in Vermont is by using available wood fuels, either to supplement heat pumps during cold weather or to heat entirely with this renewable, locally sourced fuel. In similar fashion to heat pumps, there have been dramatic improvements in the efficiency of modern chip, pellet and cordwood burning appliances, along with a large reduction in particulate matter and other pollutants.
This is another area where disinformation and a lack of understanding combine to affect the narrative. In Vermont, our forests have a continuous cycle of trees absorbing carbon dioxide and then releasing them through decay upon dying or through providing needed heat for our buildings as well as for forest products.
The carbon cycle and sustainable forest management are difficult to understand and can be counterintuitive at times. The current edition of the locally available Green Energy Times has an excellent explanation of how this works in the article “Securing Northeast Forest Carbon: Part 1.” The article explains how a sustainably managed forest removes significantly more CO2 from the atmosphere than an old-growth forest while providing a steady stream of wood products.
In summary, the use of photovoltaics and heat pumps are two ways people will choose to reduce their greenhouse gas generation. The use of woody biomass fuels is another. They also complement each other well.
