Memorandum submitted by Natural Systems
Limited (Bio 04)
1. Re item 9: "What more can
be done to make more efficient use, as an energy source, of the
by-products of agriculture and forestry (eg wood waste and other
organic waste)?".
2. Agricultural and forestry organic waste
is a low-density energy resource and is often widely distributed
and of variable composition. These factors militate against transporting
these wastes to a central waste-to-energy station. (An exception
to this is found with municipal solid waste collected from large
conurbations with a large organic content.)
3. Organic waste is, excluding woody waste
from forestry, ideally suited to anaerobic conversion into biogas
and a solid digestate, which is a valuable soil conditioner able
to return valuable nutrients back to the land.
4. An entry in the New Spirit Challenge
competition run by the IEE in 2003 was won by an entry from New
Zealand for a fully integrated energy system for dairy farms.
This described how cowshed effluent could be used to generate
biogas with a high methane content, and for this gas to be used
on-site (not stored or compressed). The biogas is used continuously
as the fuel in a combined heat and power (CHP) system. The energy
of the biogas is converted and stored both as hot water, for hygiene
purposes in the dairy milking plant, and as ice, for cooling a
dairy herd's milk output. The idea is the subject of a patent
filing by Natural Systems Limited.
5. UK dairy farming can use this system
to reduce its energy costs and deal with manure and bedding material
in an environmentally sound manner. Its practice will return valuable
organic fertilizer to the land without broadcasting obnoxious
odours, or the danger of effluent runoff polluting waterways from
raw effluent (muck spreading).
6. A dairy farm can take in additional agricultural
waste from neighbouring farms where the transport distance is
not too great. On farms where there is no requirement for heat
or cooling the CHP system can deliver electrical energy into the
local distribution network. The surplus low-grade heat, after
meeting the requirement to maintain the anaerobic digester at
its operating temperature, can be dumped if it cannot be put to
a useful purpose.
7. This system provides a low cost system
that could be replicated in high volumes helping farmers realize
value form their slurry and other wastes. Support for early deployments
of this technology will help make the systems financially viable,
this support will not be required when the number of installations
increases; as the industry will benefit from reduced costs due
to the volumes.
8. Today slurry disposal is an overhead
on the farming business and can cause considerable environmental
damage if it is not handled correctly. It also helps reduce the
emissions of methane gas by farms, methane is a green house gas
23 times more damaging than CO2.
Natural Systems Limited
January 2006
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