H2 - Hydrogen
H2/O2 STEAM GENERATOR - A device that produces steam via the reaction of hydrogen and oxygen. The subsequent injection of water allows a temperature control between 200 and 2000°;C. H2/O2 steam generators have been developed as a spinning reserve of large power plants, but have not yet been applied.
HSPF - See HEATING SEASONAL PERFORMANCE FACTOR.
HEAT GAIN - An increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources.
HEAT PUMP - An air-conditioning unit which is capable of heating by refrigeration, transferring heat from one (often cooler) medium to another (often warmer) medium, and which may or may not include a capability for cooling. This reverse-cycle air conditioner usually provides cooling in summer and heating in winter.
HEATING SEASONAL PERFORMANCE FACTOR - A representation of the total heating output of a central air-conditioning heat pump in Btus during its normal usage period for heating, divided by the total electrical energy input in watt-hours during the same period, as determined using the test procedure specified in the California Code of Regulations, Title 20, Section 1603(c).
HEATING VALUE - The amount of heat produced by the complete combustion of a given amount of fuel. The energy content of an energy carrier. Upper and lower heating value are distinguished. Upper heating value: total energy content of the energy carrier. Lower heating value: energy content reduced by the condensation energy (latent heat) of the product gas (the steam in the product gas, to be exact).
HEDGING CONTRACTS - Contracts which establish future prices and quantities of electricity independent of the short-term market. Derivatives may be used for this purpose. (See Contracts for Differences, Forwards, Futures Market, and Options.)
HOME ENERGY ASSISTANCE PROGRAM (HEAP) - A centrally operated direct payment program that assists eligible households in offsetting the cost of heating and cooling their homes. Payments are generally made in the form of dual party warrants (checks) made payable to the applicant and their designated utility company. The program is administered by the California Department of Economic Opportunity using federal and state funds. The toll-free number for the HEAP Program is 1-866-675-6623.
HOT DRY ROCK - A geothermal resource created when impermeable, subsurface rock structures, typically granite rock 15,000 feet or more below the earth's surface, are heated by geothermal energy. The resource is being investigated as a source of energy production.
HSPF (Heating Seasonal Performance Factor) - A measure of heating efficiency for the total heating output of a central air-conditioning heat pump. Efficiency is derived according to federal test methods by using the total Btus during its normal usage period for heating divided by the total electrical energy input in watt-hours during the same period. California Code of Regulations, Section 2-1602(c)(7).
HYBRID VEHICLE - Usually a hybrid EV, a vehicle that employs a combustion engine system together with an electric propulsion system. Hybrid technologies expand the usable range of EVs beyond what an all-electric-vehicle can achieve with batteries only.
HYDROELECTRIC SPILL GENERATION - Hydroelectric generation in existence prior to January 1, 1998, that has no storage capacity and that, if backed down, would spill. This term also refers to a hydro resource that has exceeded or has inadequate storage capacity and is spilling, even though generators are operating at full capacity.
HYDROGEN - H is the chemical symbol for hydrogen, the lightest element of the table of elements and the most abundant element of the universe. In general, hydrogen will be found in molecular form, i.e. as a hydrogen molecule composed of two hydrogen atoms (H2), or in other compounds (e.g. in water - H2O, organic substances). Hydrogen as secondary energy carrier is seen as the key component of a global renewable world energy supply.
HYDROGEN AS SOLAR ENERGY CARRIER - Solar hydrogen energy economy.
HYDROGEN ENERGY ECONOMY - An energy economy where hydrogen is used as the secondary energy carrier.
HYDROGEN LIQUEFACTION - Liquefaction of hydrogen, which is gaseous at room temperature, by cooling it below -253°C (20 K).
HYDROGEN MOTOR - Combustion engine which uses hydrogen as a fuel.
HYDROGEN PROPULSION - Mobile propulsion system that uses hydrogen as fuel. The propulsion energy is produced in a fuel cell and an electric motor, in a combustion engine (hydrogen motor) or a gas turbine.
HYDROGEN JET ENGINE - Hydrogen hydrogen fueled jet engine for aviation use.