Agriculture Reference
In-Depth Information
does not suffer from the problem of intermittence that is inherent to wind and
solar resources. In this respect, biomass more nearly resembles fossil fuels than it
does other renewables. Indeed, geologists tell that fossil fuels are simply fossilized
biomass.
For most of recorded history, biomass was mankind's principal energy source,
mainly in the form of wood used for cooking and heating, and as foods to “fuel”
human labor and beasts of burden. With the industrial revolution, fossil fuels cap-
tured this dominant role. Today, biomass still accounts for 15% of worldwide
primary energy consumption, but, significantly, the fraction is much higher in
developing nations than in developed ones.
Wastes generated by the forest products industry of East Texas include logging
residues left behind after harvest as well as bark, wood chips, and sawdust generated
at mills. In general, the wood wastes generated by modern mills are highly utilized;
indeed, forest mills are the largest biomass energy users in the nation today, generat-
ing more than half of their large energy requirement on-site. Many mills, including
currently five in Texas, generate electricity for local use or occasionally for resale to
the grid.
Urban sources of biomass may represent some of the best opportunities for
increasing biomass near-term presence in the energy mix. Wastes that would
otherwise be landfilled are a particularly good potential fuel source, since the
producer is charged a tipping fee for their disposal. Methane gas generated and
captured at existing landfills or at municipal sewage treatment facilities is another
important form of urban bio-energy. A final advantage of these wastes is that
their supply is surprisingly reliable, much more than agricultural commodities
that fluctuates annually with the vagaries of markets, weather, and government
policy.
Plants use photosynthesis to grow and produce biomass. Also known as biomat-
ter, biomass can be used directly as fuel or to produce liquid biofuel. Agriculturally
produced biomass fuels, such as biodiesel, ethanol, and bagasse (often a by-product
of sugar cane cultivation) can be burned in internal combustion engines or boilers.
Typically, biofuel is burned to release its stored chemical energy. Research into more
efficient methods of converting biofuels and other fuels into electricity, utilizing fuel
cells is an area of very active work.
13.7.1 Liquid Biofuel
Liquid biofuel is usually either a bioalcohol such as ethanol fuel or a bio-oil such
as biodiesel and straight vegetable oil. Biodiesel can be used in modern diesel vehi-
cles with little or no modification to the engine and can be made from waste and
virgin vegetable and animal oil and fats (lipids). Virgin vegetable oils can be used
in modified diesel engines. In fact diesel engine was originally designed to run on
vegetable oil rather than fossil fuel. A major benefit of biodiesel is lower emissions.
The use of biodiesel reduces emission of carbon monoxide and other hydrocarbons
by 20-40%.
Search WWH ::
Custom Search