Renewable energy sources for hospitals
Hospitals and health systems around the world are investing in clean, renewable energy to protect the health of their patients and communities, attract and retain top-tier talent, increase the resilience of their operations to disasters, and reduce energy costs and price volatility. Combining renewable energy with electricity storage can help hospitals remain operational during extreme weather or other disruptions to the electric grid.
According to the EPA, renewable energy includes resources that rely on fuel sources that restore themselves over short periods of time and do not diminish. In practice, most renewable electricity in the US comes from wind and solar power, as they are clean, readily available, and inexpensive. Thermal energy (such as steam, heat, and hot water) is more challenging than electricity. Biomass-powered combined heat and power plants are used by a number of health care facilities but raise concerns about sustainable forestry, carbon, and local health impacts.
Especially when paired with heat recovery and powered with renewable electricity, geothermal heat pumps are very clean but require a significant initial capital commitment. Air source heat pumps are a great option for smaller spaces but may not be feasible for large facilities. Emerging technologies such as green hydrogen may prove effective at decarbonizing thermal energy but will need to increase in scale before they are cost-effective for health care.
Renewable energy definition and sources
Renewable energy sources include sun, wind, moving water, organic plant and waste material (eligible biomass), and the earth's heat (geothermal or air- and water-source heat pumps). Some renewable energy technologies can have a negative impact on health and the environment. For example, large hydroelectric dams can lead to significant methane emissions when land is flooded and impact fish migration, and biomass combustion can contribute to air pollution and deforestation. Other technologies such as solar, wind, and small-scale hydroelectric are less harmful, but it is still important to plan projects responsibly.
Conventional energy sources include combustion of fossil fuels (coal, natural gas, and oil) and the nuclear fission of uranium. Fossil fuels have environmental and health impacts related to mining, drilling, extraction, and transmission, and they emit greenhouse gases and other pollutants during combustion. Although nuclear power generation emits no greenhouse gases, it does require mining, extraction, and radioactive waste storage that has significant long-term health and environmental risks. Additionally, accidents at nuclear facilities, while very rare, can have devastating impacts on the environment and human health.
In 2019, 18% of U.S. electricity was generated from renewable energy sources.
Types of renewable energy
Solar energy is utilized in three formats: photovoltaic (PV), solar thermal, or concentrated solar power. Typically, the term “solar power” refers to solar PV panels that convert energy from the sun into electric power. Advantages of solar PV include the predictability and free availability of the sun around the globe. Solar PV is also free of emissions during operation, uses systems that are scalable, portable, and easy to deploy, and produces the most power when the grid is most strained (hot, sunny days when people are running air conditioning). The economics of PV technology have improved dramatically over the last decade, and millions of residential rooftop, commercial, and utility-scale projects have been installed. Today, solar and wind power provide the lowest-cost electric power around the world, with prices continuing to fall.
Solar PV’s primary disadvantage is that it’s intermittent and lacks availability as a 24/7, base-load power source unless paired with storage. Solar-plus storage (typically lithium ion batteries) is becoming increasingly popular and cost effective as a resilience strategy to protect against power disruptions related to extreme weather and other grid malfunctions. Solar-plus storage also allows facilities to reduce peak demand and utility demand charges.
Solar thermal technology, which uses energy from the sun to heat water, has been adopted in health care institutions and can be economically beneficial for heating water and buildings or augmenting conventional steam or hot water systems.
Concentrated solar power (CSP) uses light-focusing technologies and mirrors to concentrate the power of the sun, producing steam that generates electricity or powers other thermal applications. CSP technology is generally most economical at a very large scale and in locations with exceptional solar resource availability, such as the desert. Thermal energy storage means CSP can continue producing power after the sun sets. New AI-optimized systems are increasing the efficiency of CSP and allowing it to operate at temperatures high enough to power even the most heat-intensive industrial processes.
Wind turbines harness the natural flow of air to produce power. Moving air passes over blades that create a pressure drop, which spins a shaft and induces an electrical current within a generator to create electricity. Wind turbine technology is not new, but economics have improved dramatically in recent years as costs have come down and size and efficiency of turbines have improved. Today the largest wind turbines have blades more than 350 feet long, stand almost as tall as the Eiffel Tower and generate enough electricity to power more than 15,000 homes.
Currently, about 7.3 percent of U.S. energy is produced using wind sources, and this percentage is growing quickly. Wind power has many advantages: It is freely and abundantly available in many locations, has no emissions in operation, and can generate large quantities of electricity in a distributed fashion. Like solar power, commercial-scale wind farms also generate electricity more economically than coal, hydro, nuclear, and natural gas plants.
Drawbacks include a lack of viable wind in some areas. Wind is also an intermittent (though predictable) source of energy that cannot easily be used as a base-load power source without the aid of large storage systems. Wind power may have negative impacts on birds and bats, and it can create concerns about land use and landscape views if sited inappropriately. Wind projects require careful siting, planning and development to balance the objectives of a project with the needs of the surrounding community and environment.
Geothermal technologies transfer the earth’s energy into heat or electricity. There are two different geothermal technologies: geo-exchange and geothermal hydrothermal power. The most common form of geothermal energy utilized in the US is geo-exchange, or ground-source heat pumps. Ground-source heat pumps take advantage of the constant temperature of the earth below ground (which stays cooler than the surface in the summer and warmer in the winter) by pumping water into deep wells drilled around a building. This technology can provide heat in the winter and air conditioning in the summer. It is most economical in latitudes where fossil fuels are utilized for heating and have a higher price. The efficiency and economics of geothermal heating can be improved by capturing waste heat from a facility. Ground-source heat pumps use electricity to move and compress water and are cleanest and more economical when paired with renewable electricity.
Geothermal hydrothermal power involves digging deep wells in geologically active areas where water is heated by the earth, then pumping that heated water or steam to the surface to generate electricity through a turbine. While attractive, this form of power is not economical or accessible unless a project’s location coincides with geothermal activity near the earth’s surface (such as the geysers at Yellowstone), making its application quite rare.
Biomass is a renewable energy source that comes from organic plant material. Plants capture carbon in the atmosphere, which is released when burned. This process is different from burning fossil fuels, which releases carbon that has been sequestered in the earth’s crust for millions of years. Still, biomass is only truly carbon neutral when new plants are grown to sequester the carbon of those that are burned. There can be a significant time lag between burning and regrowth, which is concerning given the need to quickly reduce emissions.
Open-loop biomass fuels are sourced from byproducts not intended for use as a fuel, such as agricultural residues or sawmill byproducts. Closed-loop biomass fuels are planted and harvested as crops for specific use as fuel, such as switchgrass. Biomass fuels can be burned in boilers to produce steam to make electricity or heat industries and homes. Biomass may transfer energy through chemical decomposition such as anaerobic digestion and create biogas, which can also be burned to generate power.
When sourcing biomass fuels to meet renewable energy goals, it is vital to consider environmental effects such as non-carbon combustion emissions and land use impacts from closed-loop biomass fuels. The burning of biomass can produce harmful and toxic pollution, especially if waste such as construction and demolition is incorporated into the fuel mix. Given the health mission of hospitals, the fuel source supply chain and local health impacts of a biomass project should be given careful consideration.
Biogas is formed when organic material decomposes in an anaerobic environment versus decomposing aerobically (with oxygen). The principal component of biogas is methane, but unlike fossil fuels it does not create anthropogenic carbon dioxide emissions when combusted. Biogas can be used in its raw form as a heating fuel or for electricity production with a turbine or engine, but impurities such as hydrogen sulfide and siloxanes require special cleaning or emissions control equipment.
Alternatively, impurities can be removed to make renewable natural gas (RNG), which can be injected into the natural gas pipeline and used for heating or base-load electricity production. RNG can also be used in vehicles as a fossil fuel alternative. Biogas can typically be found at landfills, agricultural manure digesters, wastewater treatment plant digesters, brewery and distillery waste digesters, cheese plant digesters, and food waste digesters. Each source has unique biogas properties that need to be tested to understand cleaning requirements, methane content, and gas volumes, which drive project viability.
Low-impact hydroelectric sources
Hydropower or hydro-energy is a form of renewable energy that uses the water stored in dams and flowing in rivers to create electricity. Falling water rotates the blades of a turbine, which spins a generator and converts mechanical energy into electrical energy. Hydropower accounted for 6.6% of total U.S. electricity generation in 2019. Benefits of hydropower include emission-free operation, 24/7 base-load availability (unlike solar and wind), and abundant potential around the globe.
If not done properly, it can have negative impacts on aquatic species, wetlands, river habitats, and people living along the water. In recent years, “run of river” and “kinetic flow” technologies have demonstrated fewer negative impacts on wildlife and habitats. These new technologies have a smaller footprint and use the kinetic flow of a stream versus the pressure head (change in water level) method of a large dam. These “small hydro” technologies still provide the potential benefits of this renewable energy source.
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