The Mayor's draft water strategy - london.gov.uk - Greater London ...

mixed with cold water in the sewer. FOG
can also be a problem for local authorities
if it is illegally ‘dumped’ with domestic or
commercial refuse.
Wastewater management and energy
5.26 Used cooking oil (UCO) can be converted
into biodiesel and sold as a transport fuel. As
a direct replacement for diesel fuel distilled
from crude oil, it meets the government’s
Renewable Transport Fuel Obligation’s
sustainability and environmental criteria as
well as avoiding the problems described in
the previous paragraph. UCO is collected
from City Hall and the London Fire Brigade
Headquarters as well as from Transport for
London and Metropolitan Police catering
sites across London for recycling into
biodiesel. The London Waste and Recycling
Board is setting up a brokerage service
to link the sources of UCO to biodiesel
producers in order to promote recycling and
to encourage the use of biodiesel in public
sector transport fleets.
5.27 The treatment of sludge (see paragraph 5.29)
can provide an additional source of energy.
Mogden, Long Reach, Deephams, Hogsmill
and Beddington sewage treatment work
generate electricity by using sewage gas to
fuel gas engines. There is the potential to
increase the amount of electricity generated
and to export this to the public supply
network. Sewage gas can also be used as a
vehicle fuel, and there are many examples
of this being done around the world but not
currently in London. Utilising sewage gas,
which is mainly methane, in this way reduces
the release of this powerful greenhouse gas
to the atmosphere.
5.28 In the slightly longer term, sewage gas can
become an important source of non-fossil
fuel hydrogen for use in stationary fuel cells
and fuel cells used to power vehicles. There
have been a number of demonstrations of
sewage gas, after treatment, being used
to power fuel cells around the world but
none so far in the UK. The use of fuel cells
in vehicles have been very successfully
demonstrated by the three fuel cell
buses operating the RV1 route for three
years as part of the CUTE (Clean Urban
Transport for Europe) project. However, the
hydrogen used in this case is derived from
conventional fossil sources.
Sludge management
5.29 The EU and Defra consider the use of
sewage sludge on agricultural land as the
best practicable environmental option in
most circumstances. The use of sludge
on agricultural land supports the vision
through the goals of healthier soils and
wiser, sustainable use of natural resources.
However, evidence submitted to the House
of Lords Science and Technology Committee
review of Water Management by Professor
Joe Morris suggests that supermarkets,
mindful of the views of their customers, have
‘distanced themselves’ from crops grown
using sewage sludge as a fertiliser 81 . This
seems to indicate that there is decreased
rather than increased public confidence in
disposal of sludge to land, although this is
not the view of water industry professionals.
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