If the magic sustainable energy goal is electrification: The additional electricity will be generated by natural gas – a fossil fuel. Solar and Wind do not have the density nor reliability to actually produce. Not to mention the cost. Today let’s discuss if we really reduce overall energy use.
Given that most of the new electricity needed to power the electric cars, buses, trucks, front end loaders, home businesses, etc.. will need to the created by additional natural gas generation, Let’s take a look at the efficiency in doing so. The purpose of going electric is to reduce CO2 emissions compared to the emissions from using gasoline, diesel fuel, heating oil, kerosene, heavy oils, propane, natural gas, and coal. Whether CO2 is actually reduced is a very complicated topic for another day. Today, let’s just look at whether using natural gas to power Maine via electricity makes sense.
The electricity created by burning natural gas in a combined cycle (CCNG) plant will be at best at a 50% efficiency rate. This means the molecule of natural gas is burned and the energy is transformed into useful electricity at a 50% rate, so over half of the potential energy of that natural gas molecule is lost – process losses and waste heat. The combined cycle plants are currently the most efficient plants. Older natural gas and oil plants which are called upon during peak usage have much lower efficiencies. It is estimated that the ISO New England grid fossil fuel plants operate at about a 30% efficiency overall.
After producing the electricity by burning any fuel to generate electricity, one must then subtract an 8-10% efficiency line loss, especially in winter leaving an at best 42% efficiency delivered to the house wall (CCNG). This means that the electricity generated by natural gas now ready to be used at your wall socket starts with a 42% efficiency of the natural gas. If you were to use an electric resistance plug-in space heater that turns 100% of the electric into useful heat in your room, then the efficiency of using natural gas to heat your room is 42% from the source.
How about heat pumps? Heat pumps use the wall delivered electricity and then multiply efficiency by extracting heat from the outside air. It is an impressive technology. But does it make sense to use natural gas to create space heat through an electrical appliance like a heat pump compared to using a central heating system with multiple zones for control of total home comfort? Also, most include efficient domestic hot water production too.
Ductless heat pumps do in fact multiply the electric efficiency by extracting free heat from the outside air. Thus average Ductless heat pumps are claimed to have an average of 270% efficiency on the use of the incoming electricity. Remember, electricity is only 42% efficient at the wall. So if a heat pump then uses that best case delivered from the generating station efficiency and applies its impressive 270% avg efficiency you get .42 x 2.7 = 1.134. Which is an efficiency of using natural gas, turning it into electricity, sending it over wires and then using the refrigeration process to bring in outside heat of 113.4%? pretty good, if the whole process is the best case.
However, compared to current natural gas, propane and now oil boilers and furnaces that are at 95% efficiency it is not much of a net energy gain. How about cost savings?
Cost
Electricity costs about $6.00 for the same amount of Btus heat capacity of a gallon of heating oil. So the homeowner gets 270% efficiency of a $6.00 per gallon oil equivalent of electricity. So, the btus from a heat pump may cost slightly less than $3.00 oil. If all goes well. A single head Ductless heat pump costs between $3500 and $4,000. The heat pump is a room heater as it only heats a small space. Maybe one zone in the house. So a DHP displaces perhaps 300 gallons of an average home 800 usages. And replaces the $3/gal oil with at best $2.00/gal electricity. So maybe saving $300 per year.
Another topic
And peak electric generation efficiency is much less as additional plants must come online.
If in-State generation (the idea to keep $ in Maine), then intermittent solar and wind is the only allowable -biomass and hydro is out. Windmills and solar panels are made in China. Wind and solar farms are usually owned by foreign or out of State conglomerates. The premium price paid for that power to these entities goes to them and does not stay in Maine. So we are still sending $ out of State. We just destroyed the beauty of Maine in order to do so. And we get higher electricity prices.