Memorandum submitted by Alpheco Composting
Ltd (Waste 58)
EXECUTIVE SUMMARY
1. Local composting for recycling biowastes
to topsoil offers very significant savings in road haulage and
higher efficiency with better quality of compost than if collection
and treatment are under entirely separate contracts.
5 & 8. The role of composting should cover
food as well as agricultural and botanical "green" wastes
and could include sewage sludge cake very efficiently. Anaerobic
digestion should not be over promoted on the mistaken assumptions
that:
— aerobic composting does not recover
useful energy because it can deliver renewable heat efficiently
and 4/5th of electricity is consumed as heat;
— aerobic composting does not need uneconomic
quantities of bulking agent,
— electricity from anaerobic digestion
may not curb climate change as much as the organic matter consumed
in its generation would achieve when applied to topsoil.
9. Efficient novel technologies would be
encouraged by:
— Avoiding simplistic percentage targets
for recycling and composting;
— Removing the administrative barriers
between waste collection and waste treatment contracts and between
separate grant support for commercial and municipal waste management;
— Awarding comparable ROCs for renewable
heat energy as well as for renewable electrical energy and relate
those ROCs to amounts delivered and consumed rather than generated,
or by replacing ROCs with tax incentives for the consumption of
renewable energy.
DETAILED SUBMISSION
1. Localisation for recycling biowastes
to topsoil.
(a) We welcome localization as opposed to centralization
especially for biodegradable wastes. Food wastes, garden wastes
and biosolids (sewage sludge cake) arising from human homes and
work places can be co-composted and the organic product applied
locally. If all the biowastes of a town were to be co-composted,
the product would annually improve an area of farmland, parks
and/or gardens equivalent to only some 20% of that town's built
up area; a local surfeit of compost is virtually inconceivable
if the quality and price are right.
(b) We have calculated in a Suffolk setting that
three satellite-composting facilities each of about 10,000 tonnes
per year, would reduce "biowaste collection miles" by
42% compared to having one 30,000-t/yr plant. Such local sites
will facilitate use of the renewable heat recovered and also mean
fewer compost distribution miles. Management over the Internet
etc. now allows suitable technologies to give virtually the same
economies of scale as are expected of larger, more centralised
plants.
(c) The biowastes' collection method has more
effect on compost and digestate quality than the process itself,
and that is most probably similar with recyclables like glass,
paper, plastics and metals. There is therefore a case for linking
collection and treatment contracts for each type of material by
removing the WCA /WDA "barrier" that sufficed when mixed
waste was merely tipped in landfill or an incinerator.
(d) Efficient management of biowastes should
differ from that of dry-recyclables:
— because the former begin to putrefy
so need weekly collection while dry-recyclables can be collected
fortnightly;
— compost being of low price per unit
should be used locally while recyclables generally need bulking
up for more distant processing.
2. No comment.
3. No comment.
4. Incentives
IT and recent legislation could allow waste
authorities to set a Council Tax rate that anticipates the same
waste management costs as in the previous year, thus ensuring
continuity of service. Subsequently the waste authorities could
send households a cash rebate that is proportional to their increased
recycling and composting, ideally as measured per property by
"chip & bin" accounts at year's end. Since any cash
"carrot" is worth at least three "sticks,"
especially when the latter are hidden among bigger budgets, this
could stimulate competitive chatter and so promote recycling and
composting.
5. & 8. The role of composting and the
promotion of anaerobic digestion
(a) We recommend that the role of aerobic composting
is not restricted to "green" botanical wastes by over-promotion
of anaerobic digestion (AD). Rather we urge that the potential
for local co-composting of municipal and commercial food wastes
together with "green" plus agricultural waste and even
with biosolids is equally promoted so that the true capital and
operational costs of each be ascertained. (b) The strong promotion
of AD in Waste Strategy for England 2007 seems to have been based
on the generation of a modest amount of electrical energy and
three mistaken assumptions:
— That composting (ie aerobic digestion)
does not recover energy was Mistake 1. Our in-vessel composting
systems can recover heat energy without flames in a way
that allows that heat to be delivered to leisure centers, housing,
office or area heating systems and to green houses or poultry
sheds. The total amount of electrical plus heat energy from an
AD plant is about the same as the renewable heat possible from
aerobic composting. It may also be noted that the heat from AD,
which is over half of the energy released, may not be useable
in UK due to planning restrictions on the locations of AD plants.
(Agrilabs of Canada is the only other composting system we know
of that recovers heat but like Horstmann, which may also
recover some heat, it is entirely static so that heat may not
be deliverable without excessive transmission losses.)
— Mistake 2 was that composting of food
wastes necessarily requires very large amounts of bulking agent
to ensure air porosity. In-vessel systems that have sufficient
and well-designed aeration sub-systems only need about 15% bulking
agent.
— Mistake 3 was to assume that the
energy and carbon benefits of compost and digestates in soil are
limited to the plant nutrients that they bear substituting for
synthesized fertilisers.
Mistakes 1 and 2 apparently stem from reports
by DEFRA's consultants that only considered one particular in-vessel
composting technology, which exhausts all heat to atmosphere and
has a relatively weak aeration system.
Mistake 3 arose in those reports and the Environment
Agency's WRATE tool by not valuing the (admittedly not yet fully
quantified) benefits of compost and digestate in:
— Reducing the fossil fuel required
by farmers to irrigate, plough and cultivate;
— Increasing fields' capacities to
hold rainwater and thereby reduce rain-runoff that contributes
to flooding down stream through flash volumes and deposited soil.
Run-off also removes soluble fertilisers that need replacement
and may promote eutrophication downstream.
— Increasing crop yields, which is
particularly significant for organic farmers.
6. No comment.
7. Potential for the proposals in the Waste
Strategy to tackle the UK's contribution to climate change
Our estimates are that if the 6 million tonnes
of food wastes per year in UK were digested or composted, the
outputs could be:
| Electricity
| Heat | Dried Solids
|
Anaerobic | 1,476 GWHe
| 2,040 GWHh | 450,000 tonnes
|
| Aerobic with heat | Nil |
3,400 GWHh | 1,676,000 tonnes |
| |
| |
Agricultural and "green" garden wastes and biosolids
might double those figures. So it is questionable—but not
established —whether the electrical energy from AD merits
the reduction in the quantity of compost/ digestate that could
be recycled to benefit topsoil. N.B. Our calculations and assumptions
need peer review, perhaps by an academic institution to avoid
any prejudice that may pertain to some consultants.
Meanwhile we believe that climate change will make healthy
topsoil increasingly valuable. Also that transportation fuel requirements
may well mean that satellite composting plants can contribute
more to tackling climate change than can AD plants; the latters'
intrinsic capital costs, which must include connections to the
National Grid, necessitate larger facilities counter to the proximity
principle and often ill-placed for their heat energy to be used.
It is for those reasons that we feel the Waste Strategy's
tilting of our particular playing field towards AD, plus the double
ROCs for electrical energy for AD but none for heat energy, has
impaired our composting systems' potential contribution.
8. See 5 above.
9. Potential for Government action to encourage the most
efficient novel technologies
(a) Avoid setting simplistic targets that can discourage
efficient novel technologies.
The Waste Strategy 2000 targets that 25% of household waste should
be recycled or composted, stimulated the collection of "green
wastes", the perversity of which to meet short-term percentage
targets, is apparently now recognized if not acknowledged. We
assert "perverse" because the large bio-bins widely
issued to attain that target, forced the use of big refuse collection
vehicles that are inefficient for food wastes while also discouraging
home composting. If the collection of "green" wastes
had been called "harvesting" then the way that they
counter the EU Landfill Directive's use of 1995 arisings as the
base line, should have been clear.
Thus simplistic percentage targets that led to the co-collection
and treatment of woody matter together with food and truly green
and soft wastes, turned a renewable energy source into a net consumer
of energy (embedded and revenue). Therefore in the consultation
preceding Waste Strategy 2007 we suggested that for the proposed
target for 40% of household wastes to be recycled or composted,
it should be made clear that "household" should NOT
include "garden".
(b) Remove the administrative barriers between the management
of:
— Collection by WCAs and treatment by WDAs so that
if the WDA saves disposal costs compared to landfill and perhaps
buying in LATS, those savings can be transferred to improved collections,
which are key to product quality.
— Municipal and commercial schemes where the former
have been grant-supported by DEFRA and the latter by dti/BERR.
DEFRA's New Technologies Demonstrator Programme (part of
the Waste Implementation Programme 2004) selected nine out of
90 applicants for significant grant support. The selection criteria
were made clear but by assessing cost-efficiency on the tonnage
of municipal wastes to be processed (ie disregarding collection
methods and commercial biowastes), they perpetuated those two
administrative barriers to the disadvantage of more holistic schemes
that are only now being sought.
In our case RPS as DEFRA's consultants ruled out our application
on the grounds that the food-wastes' collection method we proposed[176]
would " . . . be in competition with . . .
" the "green waste kerbside" collections that DEFRA
was then subsidizing for selected waste authorities.
(c) Award comparable ROCs for renewable heat energy as
well as for renewable electrical energy and relate those ROCs
to amounts delivered and consumed rather than generated.
According to Energy Consumption in the UK (dti/Office of
National Statistics 2006), the domestic energy consumption depicted
above is 79% for direct heat and remarkably little for lighting,
computing etc. and for motive power. In common usage "power"
and "energy" are often taken to imply only electricity
but those consumption figures show it is misleading to exclude
heat energy.
Secondly both electrical and heat energy are subject to transmission
losses so consumption or delivery rather than generation, production
or recovery amounts should be used to compare the efficiency of
novel technologies.
The offer of double ROCs for electrical energy from AD caused
our Bradford prospects to cancel their order for our innovative,
combined heat with composting (AC+ CHC) in favour of anaerobic
digestion with combined heat and power (AD+ CHP).
Alternatively remove ROCs altogether to prevent distortion
of the market possibly to the detriment of the most efficient,
novel technologies, and replace them with tax benefits for the
delivery/consumption of renewable electrical, heat or motive energy
that replaces energy derived from fossil fuel.
Neil Winship
Alpheco Composting Ltd
January 2008
176
It was on the lines that we suggested in January 2003 to the Environment,
Food and Rural Affairs Committee as was then published as EV177
in Volume II of the Eighth Report of Session 2002-03. Back
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