Page 100 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

7.1.6 Biofuels

Biofuels are produced from specially-grown products such as oil seeds or
sugars, and organic waste e.g. from the forest industry. These fuels are
called carbon neutral, because the carbon dioxide (CO 2) released during
burning is offset by the CO 2 used by the plant when growing.

Alcohol is distilled from fermented sugars and/or starch (e.g. wood or grain)
to produce ethanol that can be burnt alone, or mixed with ordinary petrol.

Biodiesel is made through a chemical process called transesterification
whereby the glycerin is separated from fat or vegetable oil. The process
leaves behind two products methyl esters (the chemical name for biodiesel)
and glycerin (a valuable byproduct used in soaps and other products).
Biodiesel contains no petroleum, but it can be blended at any level with
petroleum diesel to create a biodiesel blend. It can be used in compression-
ignition (diesel) engines with little or no modification. Biodiesel is simple to
use, biodegradable, non-toxic, and essentially free of sulfur and aromatics.

Brazil and Sweden are two countries with full-scale biofuel programs.
Although biofuel is carbon-neutral, concern has been raised about diverting
agricultural areas away from food production. Recently, research has shown
potential for growing certain strains in arid regions that could otherwise not
be used for producing human food.

7.1.7 Hydrogen
Although not a hydrocarbon resource, hydrogen can be used in place of or
as a complement to traditional hydrocarbon based fuels. As an "energy
carrier". Hydrogen is clean burning, which means that when hydrogen reacts
with oxygen, either in a conventional engine or a fuel cell, water vapor is the
only emission. (Combustion with air at high temperatures will also form
nitrous oxides).

Hydrogen can be produced either from hydrocarbons (natural gas, ethanol
etc.) or by electrolysis. Production from natural gas (catalytic: CH 4 + ½ O 2 →
2H 2 + CO, CO + ½ O 2 → CO 2) also produces energy and carbon dioxide, but
hydrogen has the advantage over methane gas, in that carbon dioxide can
be removed and handled at a central location rather than from each
consumer (car, ship etc.), providing a cleaner energy carrier.

Hydrogen is also produced from water by electrolysis, or in various recycling
processes in the chemical industry. (e.g. hydrochloric acid recycled in the
polyurethane process). The energy supply can then come from a renewable

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