processing which means parts of
the maize plant are left behind. In
the agro processing some of the
grain is lost as dust. At different
stages of the distribution and retailing process maize products become
inconsumable and are taken to
landfill sites, for example when the
‘sell by date’ or ‘use by date’ has
passed. When using anaerobic digestion as a solution for the management of organic waste, it also
falls under the category of waste-to
-energy technology. Although we
often associate biogas with energy,
it also accommodates an element of
recycling because the residue of the
anaerobic digestion process is high
quality biologic fertiliser. This fertiliser contains nitrogen in the form
of ammonia (NH4), phosphate
(P2O5), potassium (K2O) and traces
of sulphur (S). Substituting chemical
fertiliser with this biologic fertiliser
qualifies the agricultural operations
to be labelled as bio-farming with
regards to this input material. Using
the biologic fertiliser only the nutrients initially taken from the soil are
returned; creating environmental
equilibrium. Considering all these
elements, a biogas facility serves as
an integral and connecting technology between the sectors of agriculture, agro-processing, waste management, electricity utilities, and
the oil and gas industries.
How far is the development of
biogas in South Africa?
Dome digesters have been around
in South Africa for a few years but
the total number of realised systems is relatively small compared to
countries like China and India and
also continentally to e.g. Kenya or
Tanzania. These digesters are usually implemented as community digesters, are small scale, and do not
serve a formal commercial purpose.
Commercial biogas plants have
been built in many countries in the
world, Germany leading with about
8,000 realised commercial projects
and an installed electric capacity of
more than 2 GW. In South Africa
the industrial biogas sector is still in
its infant stage and almost no commercial biogas plant installation has
yet been completed. This late development of a South African biogas
industry has many reasons;
comparatively low electricity tariffs in an international context
an in-transparent but comprehensive regulatory framework
for permitting and licensing of
biogas plants
large gaps in the local supply
chain for track-proven equipment and services
weakening of the Rand
lack of technology comprehension in the regulatory and financing bodies
little knowledge about local biomass sources
shortage of skills with a focus on
biogas- in particular in bioengineering, microbiology, biochemistry and chemistry, and
over-all little grounded awareness of business and economic
benefits.
The local market potential is massive with the ability to contribute to
energy security and is a great opportunity for job creation. However,
there is still a passionate joint effort
of all market stakeholders required
for the further development of the
business environment in this emerging industry.
Where do opportunities lie in the
agricultural sector?
Biogas plant projects require a flexible and decentralised approach and
must fit into the local conditions at
the source of biomass. The reason
behind this is that most biomass
cannot be transported over long
distances as the energy density is
comparably l ow which results in an
economic imbalance between the
transported energy in the form of
biomass and the fuel consumed
during the road transport. Thus,
projects are often naturally deemed
to be located at the source of the
potential biomass feed material and
the revenue concept must be locally
fully integrated and serve local
needs. Farmers are the producers
and owners of the agricultural
products and by-products which are
respectively referred to as energy
crops or agricultural waste in the
biogas field. With the ability to control the biomass, farmers have the
power to initiate projects with benefits for their own interest. The organic material can be used in anaerobic digesters, reducing operational
costs (purchase of chemical fertiliser
or waste disposal fees) for the agricultural operation and/or creating
an additional income stream by selling energy. In any case, a sophisticated quantity of material is needed
to realise a required minimum economies of scale and a flexible system
design approach is necessary to
market the energy successfully. Although massive biomass data records of biochemical properties and
biogas potential have been collected all over the world within the
past decade, the knowledge is only
partially applicable to South Africa
which makes it impossible to provide reliable economic figures without some initial research. Local biomass intelligence still needs to be
developed as the biogas potential
of the sources varies significantly
with soil quality, sun radiation, rain
fall patterns, plant species, agricultural practises, mixtures of organic
feed material for the system and
biogas plant design. Basic research
on the input material and energy
infrastructure as well as energy consumption patterns around the
source is fundamental, before economically optimised and tailored
solutions can be conceptualised and
translated into financial figures.