REDUCING HOME UTILITY COST AND CARBON - Choosing Gas or Electric for Heating Applications
Gas and electricity, how do they compare where heating is required?
In many localities both natural gas and electricity are available to the homeowner, and appliances may use one or the other for heating processes. The question is which one? Electricity is often chosen because it is convenient, safe and readily available, but it usually not be the best choice for low operating cost and carbon generation.
For electricity, one unit of energy delivered to the power generating plant turns into 0.3 units of energy at the home heating site. Used for heating, electricity is about 90% efficient, so that one unit of original energy becomes 0.27 units of heat. In contrast, natural gas is delivered directly to the heating system where it has an efficiency of about 65% which, at first glance, makes electricity look better, and this is often claimed. But one unit of energy delivered from gas becomes 0.65 units of heat energy instead of the 0.27 units delivered by electricity or 2.4 times more from gas.
What about carbon? This will have approximately the same ratio as energy, so electric power generates 2.4 times more carbon. Cost is even worse because of all the complexity of the electrical generating and distribution system. To get the same total heating energy we have to spend about 3.2 times more for electricity. Clearly, from a cost and carbon point of view, gas is much preferred over electricity. Other factors may dictate choosing electricity, however, and the infrastructure for using gas may not be in place.
What about carbon? This will have approximately the same ratio as energy, so electric power generates 2.4 times more carbon. Cost is even worse because of all the complexity of the electrical generating and distribution system. To get the same total heating energy we have to spend about 3.2 times more for electricity. Clearly, from a cost and carbon point of view, gas is much preferred over electricity. Other factors may dictate choosing electricity, however, and the infrastructure for using gas may not be in place.
Where can/should we use gas?
Based on carbon generation and operating cost, gas is preferred for any heating application. Examples include household space heating, clothes dryers, cooking surfaces and ovens, water heaters, etc. Gas furnaces may be up to 97% efficient, so gas is even more favorable for space heating.
HEAT PUMPS
Heat pumps offer another way to do space heating, but their efficiency depends on the outside temperature, making them less attractive for cold climates. This issue will be address more completely in the soon to be added section on water heater replacement options that includes heat pumps.
PROPANE
Propane offers about the same carbon benefits as natural gas, but over the past 10 years or so the average price has been about $2.50/gallon and is quite volatile. At this price, propane cost is about 2.7 times that of natural gas or near the same energy unit cost as electricity.
