Fuel oil and related equipment which were often designed for lighter fuels. For comparison, BS 2869 Class G heavy fuel oil behaves in similar fashion, requiring storage at , pumping at around and finalising for burning at around . Most of the facilities which historically burned No. 6 or other residual oils were industrial plants and similar facilities constructed in the early or mid 20th century, or which had switched from coal to oil fuel during the same time period. In either case, residual oil was seen as a good prospect because it was cheap and readily available. Most of these facilities
Carbon-neutral fuel fuel. This method has the advantage of using plant matter to cheaply capture carbon dioxide. The plants also add some chemical energy to the fuel from biological molecules. This may be a more efficient use of biomass than conventional biofuel because it uses most of the carbon and chemical energy from the biomass instead of releasing as much energy and carbon. Its main disadvantage is, as with conventional ethanol production, it competes with food production. Nighttime wind power is considered the most economical form of electrical power with which to synthesize fuel, because the load curve for electricity peaks sharply