Electrification and Decarbonization: Visions for the Future of Heat
Published on June 13, 2021
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Do you use heating in your business or home? How can it be made sustainable?
Heating is one of the biggest consumers of fossil fuel energy and thus one of the biggest emissions emitters. Going forward, heating will need to be transitioned to a lower carbon-emitting paradigm. The question of how to make existing heating systems more environmentally sustainable is one with multifaceted answers. Perhaps the biggest part of this question is: How does one take natural gas fueled heating and make it sustainable?
ELECTRIFICATION VIA HEAT PUMPS
There are different ideas on how to do this. One of the more popular ones is to use heat pumps. In a residential setting, this entails replacing the furnace with an electrically powered heat pump, typically an air source heat pump (ASHP). Heat pumps work by transferring heat, via a refrigerant. In the colder months, the heat pump extracts heat from the ambient air and transfers it into the residence’s hydronic or forced air system. In the warmer months, the heat pump functions as an air conditioner, taking heat from inside the home and transferring it to the ambient air outside. The heat pump does use electricity to transfer the heat, but if this electricity is generated by renewable sources, the heat pump has virtually no emissions. According to a 2016 paper published in The Electricity Journal, heat pumps are “…often 200% to 300% efficient at converting electricity into heat and hot water for homes and businesses.” There are also ground source heat pumps, which function similarly, but by replacing the ambient air with underground piping.
HEAPS OF PRAISE FOR HEAT PUMPS
In the UK, Graham and Pauline Davidson invested £10,000 to switch from a boiler to an ASHP; now “…their total home energy bills have fallen by up to £1,000 a year.” And with £7,000 in subsidies, they expect to “… save thousands of pounds,” going forward. Almost 4,000 miles away, in Juneau, Alaska, Renewable Juneau, a nonprofit, is installing ASHPs in low-income housing. Recipients of the heat pumps report that they “… are just kind of blown away by the warmth, by the quiet, by the dry air, by the heat, by the reduced bills, by the lack of smell … .” And in Northampton, Massachusetts, homeowner John Saveson combined ASHPs with a photovoltaic solar array to make his new construction home a net zero energy building. Meanwhile in Maine, the Efficiency Maine program offers rebates for residential ASHPs and “More than 45,000 heat pumps have been installed in homes and businesses across Maine over the past five years.”
Although heat pumps are very popular with those who seek to electrify heat, some traditional oil and gas companies see their adoption as a disruptive market force. Likewise, companies are being opportunitisic and leaning into the business opportunity. In light of this, energy companies like Shell are pivoting to this new reality by deploying systems that combine the best features of a heat pump and a traditional furnace. An example of this is the B-Snug system, which uses machine learning to optimize the selection of heating method – heat pump or furnace – based on the weather conditions.
REDUCING CARBON INTENSITY OF NATURAL GAS
One way gas companies want to achieve decarbonization by making the gas they distribute more sustainable and preserve their distribution infrastructure. Some intend to do this with something called ‘electrofuels’. The idea is to dilute the natural gas with less carbon intensive fuels, or in some cases replace it entirely with low to zero carbon fuels. The plan is to electrolyze water using renewable electricity; this produces hydrogen and oxygen. Hydrogen can be added to natural gas, diluting it, but making it have lesser carbon emissions. This mixture can still be distributed using the same piping network. Since the hydrogen is produced with renewable energy, the heating fuel is partially decarbonized. Furthermore, according to a 2020 paper published in Applied Energy, “Hydrogen can also be an intermediate energy carrier that can be reacted with carbon to form carbon containing fuels and feedstocks with much higher volumetric densities and better storage and handling properties than hydrogen in its pure state.” This means that there are several pathways to integrate hydrogen-based fuels into the existing natural gas infrastructure, including sequestering atmospheric carbon into renewable fuels.
What is more, some natural gas utilities have even suggested moving away from natural gas entirely and just distributing hydrogen through their piping network. It is worth mentioning that although the only emission of burning hydrogen is water, hydrogen has about one third the energy intensity of a comparable volume of methane. This means that, in this scenario, the throughput of the piping network needs to be dramatically increased.
Renewable energy can be intermittent, such as with solar or wind; but, if it is used to make hydrogen, the gas can act as a sort of buffer that negates this issue of intermittency. During peak generation times, more hydrogen is made and stored, and during non-peak times, the previously created extra hydrogen compensates for the lack of production. Some gas utilities, National Grid in particular, have also considered creating ‘renewable natural gas’ by using anaerobic digestion or other chemical processes to create the gas from biomass. But there are concerns that this approach would need much more biomass than is currently available and would not be feasible.
FINDING A BALANCE
One happy medium has been proposed by the Cambridge, Massachusetts based nonprofit Home Energy Efficiency Team, or HEET, in the form of what they call ‘The GeoMircoDistrict’. Their plan is to transition the natural gas companies from gas infrastructure to small, neighborhood-scale ground source heat pump infrastructure at significant cost and emissions advantages. This keeps natural gas workers employed as natural gas use is gradually phased out and replaced by renewable energy. But the end result still results in the obsolescence of the natural gas infrastructure, something the gas companies want to avoid, but may eventually be forced to accept.
Overall, there is no single clear path forward toward making heating more environmentally sustainable. Electrification, through heat pumps, and decarbonization of gas both have their merits. Only the passage of time, and a sense of urgency from increasing impacts of climate change, will determine which heating paradigm will be adopted en masse in the future.
Alex Nittel has been providing research support for Gridling Global since 2018.