| CLAIMED AND REALISTIC CARBON DIOXIDE EMISSIONS SAVINGS
by
Prof MICHAEL JEFFERSON
Introduction
The writer of this Note has, for many
years, been involved in the promotion of new renewable
forms of energy, the curbing of greenhouse gas emissions
and human-induced climatic change, and related energy policy
requirements. A summary of this background is provided
below.[1] A groupof objectors
to the development proposed at Hinwick, known as CLOWD,
has asked the writer for an objective assessment of the
carbon dioxide (CO2) emissions savings and electricity
generation claimed for this proposed development by Entec,
acting on behalf of Nuon UK Ltd., in their statements in
support of the planning application.
Entec/Nuon UK Ltd. have claimed that
annual CO2 emissions savings will be achieved of 41,616
tonnes (over 1 million tonnes during an anticipated 25
year lifetime of the project).
[2] Entec/Nuon UK Ltd. have claimed
that these emissions savings are based upon electricity
generation of almost 5.59 MW, assuming maximum rated output
of 20.7 MW (9 turbines with a technical optimum of 2.3
MW each) and a load factor of 27%.[3] The
claim by Entec/Nuon UK Ltd. of electricity generated is
also the subject of critical review here.
The conclusions of this Note are summarised here for
convenience:
(1) Entec/Nuon UK Ltd base their calculation of CO2 emissions
savings upon the British Wind Energy Associaton’s “Calculations
for wind energy statistics”, which assert that wind
energy-generated electricity saves CO2 emissions from coal
(only). This is manifestly incorrect, and in a ruling dated
21st December, 2005, the Advertising Standards Authority
formally rejected such a basis for calculating emissions
savings. Using an objective basis for calculating CO2 emissions
savings, which reflects the actual split of coal, natural
gas and oil in electricity generation in the UK, the annual
savings from the proposed Airfield Farm development can
realistically be expected to be at most 16,645 tonnes annually
(far less than the 41,616 tonnes claimed by Entec/Nuon
UK Ltd.). The outcome could be as low as 13,000 tonnes.
Neither of these figures take into account the CO2 emissions
produced in the manufacture, transportation to site, and
erection (including large volumes of concrete required
to be made, transported and laid) of the wind turbines.
The large reduction from the developer’s claims is
partly due to a more realistic pattern of fossil fuel use;
and partly due to the more realistic load factor applied
to a North Bedfordshire site even at a high contour level.
(2) Entec/Nuon UK Ltd. base their claims
on a load factor of 27%. This is a fair approximation of
the UK average wind energy load factor, but this figure
is severely distorted by the 36% achieved in Northern Ireland
and the 30% achieved in Scotland. [4] In the East of England
region, based on a maximum of eight wind energy developments
(2004 only – there
were three in 2003, and two in 2001 and 2002 – clearly
at sites with significantly higher average wind speeds
than prevail in North Bedfordshire), the average load factor
was only 24%. Because the average wind speed at the proposed
location is only 5 metres per second at 10 metres above
ground level (about 7 metres per second at a hub height
of 80 metres above ground level – a figure confirmed
by the senior wind energy consultant at the National Energy
Foundation), the actual load factor at this location is
not expected to be above 18%, and could range as low as
14%. Thus, instead of electricity generated of 5.589 MW,
as claimed by Entec/Nuon UK Ltd., the actual figure is
likely to be no more than 3.73 MW, and could be as little
as 2.90 MW – about 50% of what the developer has
claimed.
(3) Entec/Nuon UK Ltd. have claimed that the proposed development
would serve the needs of 10,000 average households in terms
of electricity requirements. In fact the most optimistic
realistic assessment is for 6,330 households’ requirements
to be met. The outcome could be as low as 4,924 households.
Thus Entec/Nuon UK Ltd. have greatly exaggerated the contribution
to the number of homes that the proposed Airfield Farm
development could provide for.
CO2 Emissions Savings
The developer relies on the British Wind Energy Association
(BWEA) for calculation of CO2 emissions savings. However,
the BWEA assumes that only coal-fired electricity generation
will be replaced (an assumption ruled out of court by the
Advertising Standards Authority on December 21st, 2005),
and claims that this is because coal-fired plant is the
most flexible part of the system and because nuclear and
natural-gas fired plant should be disregarded because they
operate at ‘base-load’. It could be argued
that at present, with nuclear power being phased out, wind
energy is more likely to replace nuclear and hence unless
and until there is a change of policy there will be virtually
no CO2 emissions savings. The Advertising Standards Authority
ruling would reduce claimed CO2 emissions savings by over
50%. A more objective, and internationally accepted, way
of proceeding is to take the coal (roughly 33%), natural
gas (roughly 40%), and oil (about 1%), components of fossil-fuelled
electricity generation in the UK, together with adjustments
for their carbon components (from about 1.0 for coal to
0.68 for natural gas). This has been done here. Instead
of reducing the BWEA/Entec/Nuon UK Ltd. claims by over
50%, a more modest reduction is favoured here.
The next stepis to investigate the claim made by Entec/Nuon
UK Ltd. that CO2 emissions are justifiably based on nine
2.3 MW turbines (total rated output of 20.7 MW) running
at a load factor of 27%. This load factor is the UK average
since 2000, and close to the UK average of 28% between
1998 and 2004. However, for reasons explained in the next
section, this is an unwarranted basis for Airfield Farm.
One result is that the CO2 emissions savings have to be
greatly reduced. At best, these could be about 16,645 tonnes
CO2 per annum (contrasted with the 41,616 tonnes claimed
by the developers); at worst just below 13,000 tonnes.
No adjustment has been made for the substantial CO2 emissions
resulting from the manufacture, transportation, and assembly
of turbines, blades, towers, and ancillary equipment required – of
which the concrete requirements for access roads and foundations
is huge. Manufacturers, developers, and the
BWEA are keen to understate the latter
sources of emissions. Thus the BWEA states: “The
average wind farm in the UK will pay back the energy used
in its manufacture within three to five months, and over
its lifetime a wind turbine will produce over 30 times
more energy than was used in its manufacture.” [5] In fact the manufacturing stage is only a small part of
the total delivery and installation process, and although
exaggerated claims exist that the full cycle creates CO2
emissions which wind turbine operation can take upto 16
years to offset, a more realistic judgement is that they
take upto three years to show a positive balance.
No judgement is made of the claim by Entec/Nuon UK Ltd.
that over 1 million tonnes of CO2 emissions will be saved
over the assumed 25-year lifetime of the proposed development,
except to observe that – in line with the above calculations – the
lifetime savings would not be above 4000,000 tonnes on
the basis claimed by the developers. It is known from Danish
experience that turbines may be replaced within fifteen
years.
Electricity Generated
Entec/Nuon UK Ltd. have claimed that
with a rated capacity of 20.7 MW (nine turbines of 2.3
MW capacity), the Airfield Farm proposal would generate
5.589 MW of electricity at an assumed 27% load factor.
This represents the actual UK average load factor achieved
between 2000 and 2004. The UK Department of Industry’s
quarterly “Energy
Trends” published a Special Feature in March, 2006,
on Renewables which showed that for the years 1998 – 2004
the UK average was 28%. However, this average disguises
significant regional variations. For Northern Ireland the
figure was 36%; for Scotland 30%; for England as a whole
26%. Then within England there are significant variations,
with North East England at 21% and East of England 24%.[6] Both
these figures reflect wind speed regimes significantly
higher than the average wind speed in the area of Airfield
Farm. Although there have been adverse criticisms expressed
of the NOABL system, it is currently the most reliable
official data source available. For the Airfield Farm location
the UK Department of Industry (DTI) shows an average wind
speed at a height of 10 metres above ground level of 4.9 – 5.0
metres per second (m/s).[7] At 45 metres the average wind
speed is 6.2 m/s. At a hub height of 80 metres the average
wind speed can be expected to be barely 7 m/s. As various
reports commissioned by the DTI have shown (e.g. OXERA,
August, 2005), at average wind speeds below 8.5 m/s wind
energy developments are unviable without massive and ongoing
taxpayers’ and government subsidy.
At such low average wind speeds, which are typical of
Central England, load factors of 18% and below are to be
expected. Although it has been correctly claimed that the
UK has the best wind resource in Western Europe, that resource
is not evenly distributed. The figures given for Northern
Ireland, Scotland and English regions earlier demonstrates
that point. The same is true for many other countries – which
is why, in inland Germany for example, wind energy schemes
have load factors as low as 12% against a national average
in the range 22% to 24%. The latter figures reflect coastal
Länder and offshore results.
The implications of seeking to place wind energy developments
in low average wind speed areas are numerous: a misallocation
of national, regional and local resources; intensification
of cost and availability pressures on the industry (bearing
in mind these large turbines were originally designed for
offshore use); a reduction in regional, and thus national,
load factors; and lower CO2 emissions savings and electricity
generated than claimed and anticipated.
The resultant outcome of wind energy developments such
as Airfield Farm is that the load factor can be expected
to be below 18% (compared to the 24% East of England average,
and 27% national average), and could be as low as 14%.
This has dramatic consequences for both CO2 emissions savings
and electricity generation. Instead of the 5.59 MW output
(‘net export’) claimed by Entec/Nuon UK Ltd.
the actual outcome can be expected, at best, to be no more
than 3.73 MW – and could be as low as 2.90 MW (just
over 50% of what the developers have claimed).
It may be of interest to record that
the low average wind speed regime in Central England, and
its implications, have been pointed out to various specialists,
including Graham Sinden of the Environmental Change Unit, University of Oxford
(whose recent work reflecting the UK’s wind generic resource has been
widely quoted) and the British Wind Energy Association. None of these specialists
has attempted to counter the points made, presumably because they are inconvenient
for their narrow agendas.
Homes Provided For
Entec/Nuon UK Ltd. claim that an average 10,000 homes
will be provided for by electricity from the proposed Airfield
Farm development.
For the reasons of low average wind speed and lower than
claimed load factors, in fact at best only some 6,330 homes
would be provided for (at worst closer to 4,900). Thus
the developer has greatly exaggerated the possible benefit.
For an area of England where energy from wastes, biomass
and biofuels has far greater potential (leaving aside the
possibilities of micro-generation) this is an attempt at
imposing a gross misallocation of resources which has little
or nothing to do with optimising renewable energy developments
in the area or the country at large. As a doyen of the
UK wind energy industry, and international authority on
this subject, has remarked of this and similar plans in
the area: “It’s crazy!” Or, as the director
of a leading national organisation concerned with sustainable
development has remarked: “This is the sort of thing
gifting the nuclear option to those who favour it.”
In a broader context, the contribution
of the proposed Airfield Farm development to electricity
generation and CO2 emissions is trivial. One need not look
further than the CO2 emissions generated at the adjoining
Santa Pod Raceway, or those that will result from the planned
expansion of Luton Airport, to confirm that view. Thus
the claim in the main volume of Entec’s Environmental
Statement that the contribution to the reduction in greenhouse
gas emissions will be “Significant” is a further
gross exaggeration and distortion.[8]
June 8th, 2006.
References:
1. The writer is Chairman,
Policies Committee, World Renewable Energy Network and
Congresses. Associate Editor: “Renewable
Energy”, a journal published by Elsevier.
Described
by, and appointed as, “Expert Reviewer” by
the Intergovernmental Panel on Climate Change (IPCC), Working
GroupIII, with special reference to energysupply and use
matters.
Previously a Lead Author, Contributing
Author, Synthesis Report drafting team member, and Editorial
Reviewer for the IPCC.
Author: “Energy Policies for Sustainable
Development”, being the policies chapter of “World
Energy Assessment: Energy and the challenge of sustainability”,
UNDP/UNDESA/WEC, 2000.
Contributor/Lead Author: “World
Energy Assessment Overview – 2004 Update”,
UNDP/UNDESA/WEC, 2004.
Joint Editor: “Renewable Energy
Sources: A Guide to the Future”, Kogan Page, 1994.
Author of numerous papers and reports on climatic change
and energy matters.
He has delivered papers on these matters
in over fifty countries.
2. See Entec statement
on behalf of Nuon UK Ltd., of September, 2005, Table 2.1,
page 7.
3. See (2) supra.
4. See March, 2006,
issue of “Energy Trends”,
Department of Trade & Industry, Special Feature: “UK
onshore wind capacity factors 1998 – 2004”,
p. 29.
5. British Wind Energy
Association at
www.bwea.com/edu/calcs.html
6. DTI: “Energy
Trends”, March, 2006. Special
Feature: “Renewables”, Table 1, page 29.
7. See www.dti.gov.uk/cgi-bin/nre/noabl1.pl
8. Entec
UK Limited/Nuon UK Ltd. “Proposed Wind Farm
at Airfield Farm: Environmental Statement – Main
Volume”, Table 6.2, page 61. |
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