By harnessing household
and processor organic waste along with other organic material
and agricultural crops we can generate a valuable energy source
for local use.
The organic materials are broken down by a series of natural
biological processes. The result is production and capture
of biogas which leaving a residue for use as a rich plant
fertiliser.
The captured biogas produced from this efficient process
is a mixture of gases, the main one being methane. This is
used to power electricity generating engines or can be upgraded
into biomethane and used as a road fuel. The capturing of the biogas
has an enormous environmental benefit as the waste products
would normally go into landfill. Greenhouse gas produced in
landfill during the rotting process is released into the atmosphere
contributing to global warming.
A by-product of the electricity generation is the production
of heat. Some of the heat is used to increase the efficiency
of the digestion process but the remainder can be used for
other industrial and heating requirements.
The rich fertiliser and soil conditioner produced as a
by-product
of the Anaerobic Digestion process is used for growing food
crops and animal feed. It is a totally natural organic product,
with a low odour and a high nutrient value and is therefore
a valuable plant food. By returning the fertiliser back
to the land it completes a natural cycle of life. It also
reduces or totally replaces the need for artificial fertilisers
which are manufactured using fossil fuels and are ultimately
damaging to the environment.
Algae
for Biodiesel and Biomass
Though a little known yet a well established industry, the
commercial production of algae is a technology that has potential
to become very important in the production renewable energy.
Through selection, algae strains have been developed that have
a high oil content and have a very fast growth rate. Once harvested
and pressed the oil can be used along with vegetable oil in
the transesterification process, to produce biodiesel.
The main requirements for algae production are light, warm
water, carbon dioxide and nutrients.
By growing algae in a controlled environment alongside an anaerobic
digestion plant allows the use of some of the byproduct from
methane production i.e. the heat, the fertiliser and CO2, and
this will give improvement to the efficiency of both processes.
Algae can also be used as a direct feedstock for the anaerobic
digesters for production of biogas.
Hydrogen
Most of today's hydrogen is
created by reforming natural gas.
A renewable process to produce hydrogen is
to use electrolysis of water. As the process is very energy
hungry it is relatively inefficient, and the use of fossil
fuel-derived electricity makes this environmentally unsustainable.
However, it is possible to utilise surplus renewable generated
electricity to drive this process.
The electrolysis of water will produce hydrogen and oxygen
which can be used in fuel cell technology and in fertiliser
manufacturing.
Given future competition for land under the Food v Fuel
argument, it is clear that we cannot expect our insatiable
demand for energy to come exclusively from land-based crops.
Hydrogen will certainly have its place alongside biofuels.
Hydrogen Fuel Cells
Technological advances are bringing
the hydrogen fuel cells closer to being a commercial fuel
source and several vehicle manufacturers have work in progress.
The overwhelming advantage of this technology is that it
has zero emissions as long as the hydrogen is made and transported
using renewable energy. When used, vehicles will only emit
water vapour.
