Renewable Heating & Cooling

What Is Renewable Heating and Cooling?

Renewable heating and cooling technologies offer the potential to significantly reduce greenhouse gas emissions (GHG) from thermal applications. Specifically, renewable heating and cooling means installing and using no-to-low carbon-emitting heating and cooling equipment and fuels. Transitioning to these systems and fuels is critical to mitigating climate change.

As a coastal state, Rhode Island is extremely vulnerable to the effects of climate change, including, but not limited to, coastal erosion, more intense weather patterns, and significant public health impacts. For this reason, the state is committed to transitioning to a clean, affordable, reliable, and equitable energy future.
Resilient RI Act, HST Executive Order, 100% RE EO, PST EO

Currently, thermal energy uses – such as space heating, water heating, cooking and certain manufacturing processes – account for approximately 35% of Rhode Island’s total GHG emissions. These emissions result from burning fossil fuels, such as natural gas, oil and propane. Today, approximately 54% of Rhode Island households heat with natural gas, while another 32% heat with oil or propane.
Greenhouse Gas Emissions Report, Heating Sector Transformation Report

To meet Rhode Island’s clean energy and environmental goals, a transition to renewable thermal technologies will be vital. If navigated wisely, this transition has the potential to maintain heating reliability and safety, while supporting local job growth and investment, improving air quality, and reducing total energy costs for Rhode Islanders.

Renewable Thermal Technologies:

For Space Heating and Cooling

› Heat Pumps—Air Source and Ground Source

What They Are and How They Work: Heat pumps are combined heating and cooling systems. They work by moving heat from one space to another through a similar process to that of your refrigerator or window air conditioner: A closed loop of refrigerant combined with a compressor and an expansion valve absorb heat in one location and release it in another. This process can be used to cool a space or heat it. Importantly, because heat pumps move heat rather than combust fuel to release heat, they can be extremely energy-efficient—sometimes moving two to three times more energy than they use to operate. They also are a decarbonized source of heating or cooling, provided they run on electricity produced with renewable energy, such as wind or solar power.

Heat pumps can be classified into two large categories: air-source heat pumps and ground-source heat pumps:

  • Air-Source Heat Pumps: These pumps either draw heat from outside air to bring inside (in heating mode) or expel heat from indoors into outside air (in cooling mode). These systems have an outdoor unit that often contains a compressor and fan. You’ll often see these units sitting outside, mounted on exterior walls or roofs. The latest air-source heat pumps can now find heat in outdoor air even during New England’s coldest winters. If sized correctly, they can keep a whole home warm in winter and cool in summer.

  • Learn more about air-source heat pumps here.

  • Ground-Source Heat Pumps:: These heat pumps draw heat from the ground to bring inside (in heating mode) or expel heat from indoors into the ground (in cooling mode). These systems often use either wells drilled in the ground or buried pipes. Ground temperature is substantially cooler than air temperature in summer and substantially warmer than air temperature in winter, so ground-source heat pumps are some of the most energy-efficient systems available.

  • Learn more about ground-source heat pumps here or visit the International Ground Source Heat Pump Association (IGSHPA) website - a non-profit industry group that serves as a clearing house for educational resources, research, and publications on ground-source heat pump technologies.

  • Market Ready? Yes, both ground-source and air-source heat pumps are readily available for residential and commercial buildings. If you are interested in a system, we encourage you to reach out to multiple contractors to compare pricing and design options. National Grid maintains a list of contractors who have been approved to deliver heating and cooling systems through Rhode Island’s energy-efficiency programs, for example, but the list is not comprehensive.

› Biofuels

What They Are and How They Work: Biofuels are combustible fuels made from biological matter, such as plant matter. Some biofuels—in particular, some biodiesels—can be used as heating oil for buildings. These biodiesels are often made from vegetable oils, animal fats and/or algae. Burning biofuels releases greenhouse gases, but still creates substantially fewer emissions over biofuels’ full lifecycle (from producing to burning them) than traditional petroleum-based heating fuels. If harvested, manufactured and transported without fossil fuels, biofuels have the potential to be fully carbon-neutral.

Market Ready? Yes, biodiesel for heating oil is available on the market. In fact, Rhode Island law currently requires that all home heating oil contain 5% biodiesel, so it is automatically blended before the oil is delivered to individual customers. Home heating oils carry a label indicating their percentage of biofuel, which is denoted by the letter “B” followed by the percentage. For example: A B5 fuel contains 5% biodiesel, while a B20 fuel contains 20% biodiesel.
Biodiesel Heating Oil Act of 2013

To be fully carbon-neutral, heating oil must be 100% biofuel (i.e., B100). B100 fuel is currently available, but a traditional home oil furnace or boiler system may require some modifications to burn biofuel blends more concentrated than 20% (any number higher than B20). We encourage you to speak with a heating-system service provider to see if any adjustments are needed for your particular system.

Learn more about biofuels here.

To find a biodiesel retailer, search here.

› Renewable Natural Gas

What It Is and How It Works: The term “renewable natural gas” (RNG) can refer to either biogas or synthetic natural gas. Either can be used in place of conventional natural gas, also known as pipeline gas.

Biogas is a purified byproduct of decomposing organic matter, like manure, wastewater, and landfill or food waste. Anaerobic digesters are one type of technology that can turn organic matter into biogas.

Burning biogas still releases greenhouse gases, but biogas creates substantially fewer emissions over its full lifecycle—from production to burning—than conventional natural gas. It also diverts methane, an even more potent greenhouse gas than carbon dioxide, which would otherwise be released into the atmosphere from already-occurring decomposition processes.

Synthetic natural gas is created by using renewable electricity to split water molecules into hydrogen and oxygen and then combine the hydrogen with carbon dioxide from the air.

Market Ready? This technology is still in the developmental pilot stage. A small amount of biogas is currently being injected into natural gas pipelines in several utility jurisdictions across the country. A few pilot projects for producing synthetic natural gas are also under construction in states outside of Rhode Island.

Learn more about renewable natural gas here and here.

Learn more about biogas here.

For Water Heating

› Heat-Pump Hot-Water Heaters

What They Are and How They Work: Heat-pump hot-water heaters move heat from the surrounding air to the water inside an insulated hot-water tank. They do this through a similar process to your refrigerator: They use electricity to compress or expand a refrigerant within a closed loop. When the refrigerant expands, its temperature decreases, allowing it to absorb heat from the surrounding air. Then, when the refrigerant is compressed, it gets hotter, which heats the water in the water tank. Because these heaters move heat, rather than release heat through combustion or electric resistance, they are extremely energy-efficient. If they run on electricity generated by renewable resources, such as solar or wind power, heat-pump hot-water heaters are a decarbonized technology for hot water.

Market Ready? Yes, heat-pump hot-water heaters are readily available for residential and commercial water heating. They can easily replace an existing electric-resistance hot-water tank to save you energy and money.

We recommend you reach out to a contractor to make sure a new heat-pump hot-water heater is properly sized for your needs. Rebates from your utility’s energy-efficiency programs may also be available for this technology.

Learn more about heat-pump hot-water heaters here.

› Solar Thermal Panels

What They Are and How They Work: Solar thermal panels collect solar energy during the day and use it to heat water stored in an insulated hot-water tank. Unlike typical solar panels (e.g., photovoltaic (PV) panels), solar thermal panels do not create electricity. Instead, they are made specifically to heat water. However, they are similar to PV panels in that they are often attached to the roof of a building.

Because the sun’s energy does the heating, solar thermal systems use very little energy—just a small amount of electricity to circulate the water throughout the system. And if that electricity comes from renewable resources, such as solar or wind power, then the entire system is fully decarbonized.

Market Ready? Yes, solar thermal systems are readily available for residential and commercial buildings. However, they may not be able to meet all of your hot water needs in the New England winter. We recommend consulting a contractor to determine if a solar-thermal hot-water system is right for you.

Learn more about solar thermal panels here & get answers to common solar hot water here.

For Cooking

› Induction Stoves

What They Are and How They Work: Induction cooking works by creating an oscillating magnetic field below an iron pot or pan. Electricity creates and controls the magnetic field. When that magnetic field oscillates, the iron atoms in the pot rub against each other, causing the pot—and only the pot—to heat up. The heat from the pot transfers to the food inside, cooking it just like any other type of stove.

Induction stoves provide an extremely energy-efficient way to cook, compared to conventional electric and gas stoves, which waste energy heating the surrounding air and surfaces in addition to the pot. Induction cooking is also faster, more controlled and safer. Induction stoves can boil water in half the time of conventional electric stoves, they don’t release fumes into your home like gas stoves, and the “burners” are cool to the touch as soon as the pot is removed. When the electricity used to power an induction stove is from renewable sources, such as wind or solar power, induction cooking is fully decarbonized.

Market Ready? Yes, induction stoves are readily available for residential and commercial kitchens. Major brands offer a variety of options at various prices. Remember, though, that your cookware needs to be compatible and iron based. Check your cookware’s compatibility by holding a magnet near it. If the magnet sticks, you are good to go! Also, make sure to consult an electrician if you are converting from natural gas or propane. Induction stoves require a higher voltage plug than other electric appliances.

To learn more about induction cooking click here.

Learn how to get started decarbonizing
your heating and cooling here.

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