Methane: A highly-flammable, colorless, odorless, tasteless gas which is the main constituent of "natural gas." It is formed naturally or can be manufactured and is used as a fuel and for manufacturing chemicals.

Methanol: Also called methyl alcohol or wood alcohol. A clear, colorless, very mobile liquid that is flammable and poisonous; used as a fuel and fuel additive, and to produce chemicals.

Natural gas: A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits. It generally contains a high percentage of methane, varying amounts of ethane and inert gases and is used primarily as a heating fuel.

Nonrenewable fuels: Fuels that cannot be easily made or "renewed," such as oil, natural gas and coal.

Nuclear energy: Energy that comes from splitting atoms of radioactive materials, such as uranium, and which produces radioactive wastes.

Off-peak: The period of low energy demand, as opposed to maximum, or peak, demand.

Organic: An ecological production system based on minimal use of off-farm inputs and on practices that restore, maintain and enhance ecological harmony. Organic products are not just limited to produce and can include organic clothing, flowers, pet food and nutritional supplements.

Pay-as-you-throw programs: Residents are charged for the collection of municipal solid waste based on the amount they throw away, rather than paying for waste collection through property taxes or a fixed fee. Also known as unit pricing or variable-rate pricing, PAYT programs create an economic incentive to recycle more and to generate less waste.

Phantom load: Also called a vampire load. The consumption of power by an appliance even when it is turned off. Examples of phantom loads include appliances with electronic clocks or timers, appliances with remote controls and appliances with wall cubes (a small box that plugs into an AC outlet to power appliances).

Photovoltaic device: A solid-state electrical device that converts light directly into direct current electricity.

Photovoltaic (solar) module or panel: A solar photovoltaic product that has groups of PV cells connected to produce power.

Propane: A hydrocarbon gas that occurs in crude oil, natural gas and refinery cracking gas. It is used as a fuel, a solvent and a refrigerant. Propane liquefies under pressure and is the major component of liquefied petroleum gas (LPG).

Recycled: Material diverted from the waste stream and used to make goods. Can be pre-consumer (like factory scraps that were never used) or post-consumer (which is material made from items previously used by individuals).

Recycling: The process of converting materials that are no longer useful as designed or intended into a new product.