Renewable energy is energy generated from natural resources that is not depleted when used. The use of renewable energy has increased steadily as a result of government policy support, improved technology and significantly reduced costs. A look at the different types of renewable energy and their application to health care facilities includes:

● Solar photovoltaic. Photovoltaic (PV) systems use solar cells to directly convert sunlight into electricity. Solar PV can be deployed in any climate, although solar intensity is stronger in the southwestern United States. Systems can be mounted on the roof or on the ground or integrated into the building. Structural considerations for equipment weight, snow loads and wind loads must be considered, and shading from surrounding objects should be taken into account during design. Electrical interconnection is another key factor.

● Solar thermal. Solar thermal usually consists of hot water heating systems that circulate fluid through heat-absorbing, solar thermal collectors. These systems typically are used to heat domestic hot water, but also can be used in radiant space heating systems. The systems also require the use of storage tanks to offset the variable demand for hot water with the production of heat from the solar panels. Solar thermal systems have many of the same design issues as solar PV systems.

● Wind. Wind power is generated as wind turns a turbine connected to a generator. Wind power can be produced on-site through smaller turbines or provided by the utility company on a larger scale.

● Geothermal. Geothermal energy is taken from available heat from the earth. The most active geothermal resources are located in the western states and Hawaii. Thermal heat and electricity are produced from hot springs, and steam produced from geothermal energy. A more common application is to use the earth to transfer heat from a geothermal heat pump system.

● Biomass. Biomass energy is produced by burning organic materials or waste materials. Organic materials are typically wood pellets or chips from forest resources, scrap wood and mill residuals, but could also be waste crop biofuels (such as ethanol) or solid-waste materials. Biomass materials are burned to create thermal heat, which also can be used to run a turbine to produce electricity.

The main key to the feasibility of biomass is to find a steady, cost-effective supply of fuel. Other issues include outfitting the boiler plant for biomass supplies and dealing with emissions and ash.