| H-Coal |
| A direct coal liquefaction process that adds hydrogen and a catalyst to a coal slurry in a liquefaction vessel. |
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| Half-Life |
| The period required for the decay of half of the atoms in a given amount of a specific radioactive substance. |
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| Heating Degree-Days |
| A unit measuring the extent to which the outdoor mean daily dry-bulb temperature (average of maximum and minimum) falls below 18o Celcius for each calendar day on which such deficiency occurs. (On the Fahrenheit scale, the assumed reference temperature is 65o.) |
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| Heating Oil |
| Generic term for oils used exclusively for heating. Most often used to refer to No.2 fuel oil and to heavy fuel oil. |
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| Heavy Crude Oil |
| Oil of high viscosity, recoverable only to a limited extent (5%) by using standard production techniques. Loosely applied to crude oils with low API gravity (roughly, below 20o Celcius). |
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| Heavy Fuel Oil (HFO) |
| The fuel that remains after the refining process has eliminated the "light ends" from crude oil. Since heavy fuel constitutes the residuum of the crude barrel, it is commonly called residual fure, or resid. |
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| Heavy Oil Sands |
| Geological formations containing viscous hydrocarbons (other than coal, oil shale or tar) that barely flow at reservoir conditions. Hydrocarbons in heavy oil sands flow more readily than those in tar sands, but much less readily than those in conventional deposits. |
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| Heavy Water |
| Water in which the hydrogen atoms are the heavy hydrogen isotope, deuterium. It is sometimes called deuterium oxide (D2O). |
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| Hog Fuel |
| Fuel consisting of bark, shavings, sawdust and low-grade lumber and lumber rejects from the operation of pulp mills, sawmills and plywood mills. |
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| Hybrid System |
| A dual fuel heating system using two altenative sources of energy. The most common systems use oil and electricity. |
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| Hydro-Electricity |
| Electrical energy produced by harnessing falling water. In most cases, river water flowing through a dam turns a turbine that drives an electrical generator. |
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| Hydrocarbon |
| Any of a large class of organic compounds containing only carbon and hydrogen. The molecular structure of hydrocarbon compounds varies from the simplest, menthane (CH4), the main constituent of natrual gas, to heavier and more complex molecules, such as octane (C8H18), a constituent of crude oil. Crude oil and natrual gas are often referred to as hydrocarbons or hydrocarbon fuels. |
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| Hydrotreating |
| A petroleum refining process used to remove contaminants (specifically, sulfur, nitrogen, oxygen, halides and/or trace metals) from a petroleum fraction. Typically, the fraction is reacted with hydrogen gas in the presence of a catalyst to produce hydrogen sulfide, ammonia, saturated hydrocarbons and free metals. Hydrotreating is often used as a separtate treatment prior to more extensive hydrogenation. Also referred to as hydrofining, hydroprocessing, hydrodesulfurization (HDS) and desulfurization. |
