Have we really thought through the implications of Heat Pumps?
Steve Miller, PE
Owner of HVAC Design Solutions, HVAC and Plumbing software packages, eBooks, and apps for tablets.
To eliminate the residential use of fossil fuels, the “Global Warming/GHG” people have recommended that everyone switch to electric Heat Pumps in place of gas furnaces.?President Biden has invoked the Defense Production Act to increase Heat Pump manufacturing.?Also, S.4139 would hasten Heat Pump manufacture.?
If these recommendations are followed before the electrical grids and microgrids are converted to renewable energy, the greenhouse gases released into the atmosphere will be increased, not decreased!?
·????????To provide heating at night (no solar available) a Heat Pump operates a compressor, an outdoor fan, and the indoor fan.?A gas-fired furnace operates only the indoor fan.?That is a huge difference in electrical load.?Below approximately 10 degrees F, Heat Pumps also use electric coil elements for heating.
·????????A large percentage of the electricity to operate the Heat Pumps comes from existing natural gas or coal fired power plants.?Electrical generation losses at the power plant, and transmission losses to deliver the electricity to the end user, result in less than 35% of the fuel input at the power plant being usable at the Heat Pump.?Whereas the gas furnaces are at least 80% efficient.?Logic would say that the 35% efficient use of power plant gas for the electric powered Heat Pumps would produce significantly more GHG than the 80%+ efficient gas furnaces. ?This is true even considering the 200% to 400% Heat Pump efficiency.
·????????Existing power plants plus the current generation capacity of solar, wind, hydro, nuclear, etc., will run out of capacity on the interconnected grid systems.?Electrical generation and transmission equipment will have to be added, to meet the recommended Heat Pump additions and avoid brownouts and blackouts.
·????????A coalition of 37 scientists, entrepreneurs and academics sent a letter to Energy Secretary Granholm (regarding closing of California’s Diablo Canyon nuclear plant):?"Considering our climate crisis, failing to pass this amendment could lead to the plant's closure," the letter said. "That would not only be irresponsible, the consequences could be catastrophic.”
·????????Sulfur hexafluoride:?(Copy from EPA – “Electric Power Systems Partnership” – 4/29/2022)
“Sulfur hexafluoride (SF6) is a synthetic fluorinated compound. ?Electric utilities rely heavily on SF6?in electric power systems. ?Yet, it is also the most potent greenhouse gas known to-date.?It is 22,800 times more effective at trapping infrared radiation than an equivalent amount of CO2?and stays in the atmosphere for 3,200 years.”
(See Page 2 for Background Material)
Page 2 – Greenhouse Gas and Heat Pumps – Background Material
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Regarding Sulfur hexafluoride (SF6) - (Copy from EPA (4/29/2022)
·????????“The most common use for and largest emission source of SF6, both domestically and internationally, is as an electrical insulator in high voltage equipment that transmits and distributes electricity. The largest use of SF6?occurs in high-voltage circuit breakers, where, in addition to providing insulation, SF6?is used to quench the arc formed when an energized circuit breaker is opened.
Approximately 70 percent of all SF6?emissions in the United States is attributed to the electrical transmission and distribution sector in 2020, based on the?“Inventory of U.S. Greenhouse Gas Emissions and Sinks”. The electric power industry uses roughly 80 percent of all SF6?produced.”
·????????If our nation continues to “Electrify with Heat Pumps”, especially in colder climates where Heat Pumps are less efficient, countless new substations will be required, along with the countless circuit breakers and other SF6 gas switchgear. ?Electrical switchgear manufacturers concede to a SF6 leakage rate of up to 0.5% per year, per circuit breaker. ?If each SF6 gas-containing circuit breaker and SF6 switchgear has even a 0.4% leak rate, the amount of SF6 released into our atmosphere will be monumental.?This is also true for the switchgear in microgrids.
Regarding the effect that extensive additions of electric Heat Pumps will have on our power supply:
·????????An indicator that California recognizes the problems with existing power grids (7/4/2022):
“The energy trailer bill negotiated by Gov. Gavin Newsom's administration and approved by lawmakers late Wednesday allocates a reserve fund of up to $75 million to the state Department of Water Resources to prolong the operation of aging power plants scheduled to close. Diablo Canyon (nuclear power plant), on the coast near San Luis Obispo, has been preparing to shut down for more than five years.”?The bill is intended to maintain the reliability of the state's increasingly strained power grid and avoid the damaging prospect of brownouts or blackouts.
·????????If all existing homes that do not currently have central air conditioners are now required or enticed to add Heat Pumps to replace existing gas furnaces, the additional load on the electrical systems will be extensive. ?It is highly unlikely that existing power grids, substations, and electric services would have been designed for every residence to have either central air conditioners or Heat Pumps. ?Also, during cold nights, the simultaneous use factor of all residences’ Heat Pumps/electric coils could approach 100%.?During the summer, the newly added Heat Pump residences will be significantly increasing the air conditioning load on the electrical systems.
Regarding Heat Pump efficiency versus cold outdoor temperatures:
·????????If a Heat Pump is installed with a 3.5 COP (350% efficiency) to provide 24,000 BTUH of heating at 45 degrees F outdoor temperature, it will only have an approximately 2.3 COP at 10 degrees F outdoor temperature and will only produce about 15,000 BTUH of heating.?To produce the desired 24000 BTUH, either an electric coil is required (1.0 COP), or the Heat Pump will have to be oversized to accommodate the lower temperatures.
Regarding health effects of excessive Heat Pump installations: (Copy from extensive study “US Residential Heat Pumps”, Deetjen, Walsh, and Vaishnav, 7/28/2021).
·????????“Heat pump adoption often increases the health damages caused by air pollutants such as SO2, NOx, and PM2.5 (Particulate Matter, 2.5 micron). Compared to power plants, residential furnaces and boilers operate at lower combustion temperatures and stricter air quality regulations. That is, power plants produce significantly more air pollutants than residential heaters do. This situation—where heat pump adoption increases overall health damages—occurs for 47.5 million US houses, or 67% of the non-heat-pump housing stock.”