In March 2005 the Institution of Civil Engineers (ICE) and the Renewable Power Association (RPA) published a report titled “The Quantification of the Potential Energy from Residuals (EfR) in the UK (Lee P et al. 2005). A briefing on this report was included in Energy Journal 160, (Crudginton A. 2007). The report indicated that the potential yield from municipal solid waste and commercial and industrial waste amounts to 17% of the total UK electricity consumption. The split is 38% municipal solid waste and 62% commercial and industrial waste. That is municipal solid waste could contribute 6.5% of the total UK demand for electricity compared to its present day 0.49% contribution.
To date commercial and industrial waste has hardly contributed to the production of electricity. There is obviously a big scope here.
The report assumed optimum energy recovery from a Solid Recovered Fuel (SRF) having a high calorific value derived from Mechanical Biological Treatment (MBT) of the waste. Current practice and an uncertain market indicates that energy recovery may fall well short of this potential maximum yield.
From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of dave andrews
Sent: 26 June 2010 13:43
Subject: Re: Anyone help? : RDF a figure or range of figures for the calorific value of domestic refuse derived fuel flock (ie residue after sorting and shredding)?
– Hide quoted text –
Marvelous – many thanks Denis.. I will forward to Martin.
But as a matter of interest, how much of the stuff is there?
ie if we burnt all the stuff we chucked out, how many MW continuous would we generate?
And how much if we included all the old chairs, door and other large scale wastes that get thrown away in total?
On 26 June 2010 12:49, denis stephens <denis.stephens the at sign btinternet.com> wrote:
I hope the following helps
Mixed waste as collected at the kerb-side has a calorific value of 9 to 11 MJ/kg, about one third of that of coal.
The biodegradable portion of kerb-side collected waste obtained from a mechanical biological treatment (MBT) pre-processing plant, in which waste materials suitable for recycling/composting are separated out for further treatment and unsuitable non combustible materials such as stone are removed to tip, may be dried and compacted to produce a fuel with a calorific value of up to 17 MJ/kg, about fifty to sixty percent of the calorific value of coal. In the process of making the fuel the energy used is typically 15 to 20% of the energy value of the fuel. This fuel is known as Refuse Derived Fuel (RDF) or Solid Recovered Fuel (SRF).
The amount of biomass derived from residual waste in Cambridgeshire
has the potential to make 19MWe and about 35MWt.
From about 175,000 tpa of MSW you could make about 98,000 tpa of
biomass fuel. That fuel would be ROC able and would displace about
50,000 tpa of imported coal per year.
I believe that about 40 equivalent plants could be built.
Because the fuel is much cleaner than burning residual MSW in a
conventional plant the combustion plant is only about half the size of
an equivalent EfW plant.
The flue gas scrubbing is much less complex, and you would not be
destroying £2 to 3 million of non ferrous metals per year, in the way
that mass burn EfW does.
The residual ash content is much lower, and it is less contaminated
than the ash from conventional EfW plants.
I have tried to promote two plants like this recently in Norfolk and
Gloucestershire as part of the Waste PFI process, but conventional
unimaginative thinking linked to local government procurement rules
has deprived both of those communities of future benefits from this
approach. It has also condemned them to 25 years of playing uneconomic
gate fees, about 20% higher than would be required for these plants.
Is AD a better solution?
Mass burn incineration is the worst solution but biomass burn is also a
waste of resources.
Anaerobic Digestion is better as it does not destroy the nutrients that can
be returned to the soil in the form of fertiliser, after the energy has been
Biogas can either be upgraded to biomethane and fed into the gas grid and/or
used as a transport fuel or simply burnt to generate electricity, which ever
is most efficient for the particular site.
The quicker the waste is digested and the nearer to the site where it is
generated the less chance there is that it will generate methane into the
atmosphere. That is why we need more low-cost modular AD plants which can be
scaled to fit the amount of waste available within easy reach of the AD
plant. At present AD plants seem to be getting bigger and waste is being
transported long distances by road which is counter productive (eg Ealing’s
organic rubbish is being sent by road to Rushden in Northants!). This is
what my company AgGrowGas Ltd is working on.
The report by the National Gas Grid (attached) gives some figures for the
proportion of gas that could be generated in UK from organic wastes.
Environmental Protection commissioned a report on this subject which
estimated that 16% of all transport fuel requirements could be met by biogas
made from waste. This is more than enough to convert all urban public
transport in UK to biomethane, which would be good news for air pollution
and public health as well as for carbon reduction and energy security.
James Skinner, Sustraco Ltd, Heron House, Chiswick Mall, London W4
2PR Tel: 020 8995 3000 Mobile: 07718887352
Semantics are important.
Those favoring thermal recovery with power generation (and hopefully as CHP) as mass burn energy from waste/advanced thermal treatment technology i.e. gasification etc., are using residual MSW (rMSW), waste remaining post removal of dry recyclables and food waste.
It is only then that energy recovery via thermal means should be applied, hopefully satisfying the ‘recycle everything’ and AD folk. rMSW is only really useful for energy recovery, nothing else. If the organics are recovered from rMSW and digested the resultant digestate or more correctly ‘compost like output’ (CLO) as it is designated, is (currently) fit only for landfill, restoration of contamination land or used to grow energy crops (unlikely, as this will sterilize the land for food crops effectively forever).
After AD of rMSW the digestate/CLO can be used a fuel, recovering the residual carbon not able to be digested.
UK residual MSW has a gross CV between 9-10MJ/kg and CLO 3-5MJ/kg, depending on moisture content. If one bio-dries rMSW to enhance the CV and make an RDF, CV could increase to 10-12MJ/kg
So recycle yes, digest food/organic wastes yes but burn rMSW and CLO to maximise the total energy recovery.