Memorandum from the Royal Academy of Engineering
The Royal Academy of Engineering is pleased
to submit evidence to the House of Commons Select Committee on
Science and Technology Inquiry into Carbon Capture and Storage
Technologies. This response has been prepared following consultation
with a number of Fellows with expertise in this area.
The Committee will be aware of the Department
of Trade and Industry's recent Consultation "A Carbon
Abatement Technologies Strategy for Fossil Fuel Power Generation"
of August 2004. The Academy responded to that consultation
and our response to the DTI is annexed to this report.
The contributing Fellows are of the opinion
that fossil fuels will form a major component of energy supply
until at least 2050 and there is considerable evidence to support
this statement. Thus it is suggested that if the Government's
target of a 60% reduction in CO2 by 2050 is to be realised,
then carbon abatement technologies will be required. Carbon Abatement
Technology (CAT) using carbon sequestration is a means of undergoing
a smooth transition from a fossil based economy to a more advanced
energy supply. A number of large developing countries use fossil
fuels, particularly coal, on a very large scale and will continue
to do so for a long time and this would be an excellent technology
to export. A significant electrification of the developing world
will take place in the next few years and the UK could have a
pivotal role in assisting the developing world to progress towards
lowering CO2 emissions.
In addition to being used for electricity generation,
fossil fuels provide a route to hydrogen via gasification. Gasification
has the dual advantage that it can produce a clean fuel gas for
combustion in gas turbines via an Integrated Gasification Combined
Cycle (IGCC) producing electricity and heat. Secondly gasification
can produce, by alteration of the process conditions and in conjunction
with carbon sequestration, hydrogen. Such a plant is planned to
generate "carbon free" electricity from hydrogen by
BP, ConocoPhillips, Shell and Scottish and Southern Energy. In
this example, natural gas is used as the feedstock for a gasifier,
electricity being generated by a combined cycle gas turbine (CCGT)
and the carbon dioxide used for enhanced oil recovery (EOR) in
the Miller oil field.
Detailed responses to the Select Committee's
questions are set out on the following pages.
2. THE VIABILITY
OF CCS AS
(CAT); CURRENT STATE
There is a strong case for a trial to be undertaken
using a suitable power plant. The technology exists for CO2
removal from flue gases and this can be undertaken immediately
in a number of ways at the present time using developed technology
and either natural gas or coal as primary fuel. The efficiency
penalty of currently available carbon capture technology is too
high to be considered for a simple bolt-on addition to an existing
power station. Some other efficiency improvement technology would
be desirable to win back some of the losses associated with amine
regeneration as part of the CO2 capture process, but
even then the economics of retrofitting a power plant that may
be at or beyond its design lifetime or emissions control capability
would need close scrutiny.
The oil and gas industry in the North Sea has
also allowed the UK to develop geological, engineering, logistics
and PR skills that would be useful in CO2 sequestration
issues. Future development of CATs should trade on these skills,
rather than trying to replicate those that may exist in other
countries, to ensure that an optional position is reached in respect
of both meeting the UK's national requirements effectively and
without excessive cost, whilst exploiting overseas export potential.
Involvement with pilot or commercial scale demonstrations of relevant
technologies must form part of the future strategy. This should
be complementary to continuation of R&D into underpinning
sciences, for which the UK is rightly respected, in a vertically
integrated partnership between industry and academia.
There are several options for the continued
use of fossil fuels, mainly coal, for power generation together
with carbon capture. The choice will depend on local circumstances
and the decisions of the power companies. One route would be the
capture of CO2 from existing, possibly upgraded power
plant. In this respect, retrofitting a post combustion carbon
capture technology onto a CCGT power station could represent one
least costly, least risky and quickest option. It would enable
scale up of currently applied carbon capture technology to be
tested against all of the operational requirements previously
mentioned whilst potentially reducing the requirement for government/host
site funding because of the potential value of the CO2
being produced either for enhanced oil recovery (EOR) or as carbon
credits. Short term application to a coal fired plant is much
less attractive because of the additional costs and significant
reduction in efficiency from an already lower base figure. However,
continual involvement in the development and demonstration of
higher efficiency, ultra supercritical conventional coal combustion
technology might enable the combination with carbon capture to
be considered within a 15 year time frame. Other options being
studied for coal include gasification cycles and advanced combustion
cycles involving combustion in oxygen or oxygen/carbon dioxide
mixtures which facilitates the separation process. These options
may prove to have advantages over conventional methods in the
context of the development and demonstration of CATs. Thus it
is important that these developments should be carried out with
eventual application to both coal and natural gas fuelled plant
and hydrogen production in mind.
The technology will continue to develop after
the basic feasibility has been demonstrated. Particular lines
of development include oxygen separation technology, improvements
in CO2/H2 separation, gas turbine advances, and studies
of the behaviour of CO2 in oil and gas reservoirs and
coal seams. These studies need to be supported in UK laboratories
alongside the development and demonstration activities that may
involve international co-operation.
2.1 Projected Timescales for producing market
ready scalable technologies
Much of the technology required is available
and has been tested in this and other countries. Certain types
of plant could be constructed using existing technology in approximately
five to 15 years. There is a considerable amount of R&D required
to improve the solvent systems that are currently available to
address the efficiencies/cost issue. It is also worth noting that
the largest commercial demonstration of carbon capture is still
a fraction of that required for a 500 MW based power station,
so there may well be scale-up problems.
In the case of the BP, ConocoPhillips, Shell
and Scottish and Southern Energy project the announced time scale
is that it would commence in 2009. This uses existing technology
for a natural gas reformer plant to create hydrogen and sequester
the carbon-related gases, conversion of a CCGT unit to hydrogen-firing
and to adapt the Miller oil field topsides facilities and export
line. The Miller oil field is 240 km offshore and it would then
facilitate delivery and injection of the CO2 for enhanced
oil recovery and long term storage.
The costs arise from the separation process,
which entails a considerable loss in efficiency, transportation
and well-head operations. The overall loss in efficiency is about
30% but this estimate is subject to debate, and should be the
area in which much of the R&D effort should be directed.
The Royal Academy of Engineering Report (The
Costs of Generating Electricity, March 2004) gives the following
figures for electricity generation, and for generation with flue
gas CO2 removal by sequestration respectively.
COST OF GENERATING ELECTRICITY WITH RESPECT
TO CO2 EMISSIONS COSTS (£30 PER TONNE)
|Technology||Basic Cost (p/kWh)
||Cost with Carbon
|Coal Fired Pulverised Fuel||2.5
|Coal Fired Integrated Gasification
|Gas Fired Combined Cycle Gas Turbine||2.2
On this basis the total cost is comparable with that for
renewable energy. The embedded fuel costs play a significant role
in fossil fuel electricity generation and the sensitivity to a
20% change in fuel price has been examined in the Academy's report.
This suggests that the upward pressure of costs on natural gas
is greater than that for coal.
The typical cost of sequestration is about 1-2.5 p/kWh, whilst
the cost for EOR is about 0.5 to 1 p/kWh, but the latter process
is limited to a small number of suitable fields.
However the UK Offshore Operators Association (UKOOA) have
indicated that in the case of offshore sequestration the cost
of the well-head operations may be higher than previously estimated.
2.3 Geophysical feasibility
Evidence suggests that the technology is feasible since the
techniques are already available and employed using carbon dioxide
for enhanced oil recovery. It is estimated that the total capacity
for CO2 in aquifers in the North Sea is 13 times the
estimated output of the UK to 2050. Although natural gas has
been stored in some of these aquifers for many thousands of years
without leakage care has to be used in selecting appropriate reservoirs
with regard to rock cracking and the loss of the stored CO2
by seepage. Whilst the behaviour can be modelled it is impossible
to predict the situation in the long term, say 100 years and it
will therefore be necessary to install appropriate monitors.
2.4 Other Constraints
The Government will need to develop and enact enabling and
enduring policies to allow electricity from these projects to
compete with those using traditional fossil fuels. At present
Decarbonised Fuels (ie hydrogen etc.) are not competitive with
the fossil fuels from which they are derived and would need enabling
government policy valuing carbon at a level similar to Renewable
Obligation Certificates (ROC) available to renewable energy sources.
In the immediate future a major hurdle is the legality of
the disposal of CO2 offshore where enhanced oil recovery
is not appropriate. This is a well-known issue but has to be resolved
quickly before any considerable activities could take place.
Another matter relates to the planning of a complex activity
involving a number of multi-national companies.
A further issue relates to the long term ownership of the
reservoirs which will have to monitored and maintained for a considerable
3. THE UK GOVERNMENT'S
FUNDING CCS R&D AND
INDUSTRIAL R&D IN
The emphasis must be on reducing the efficiency losses currently
associated with CATs so that fossil energy is conserved and on
the safety, legal and public acceptability issues that are currently
shrouded in uncertainty.
The UK industry retains: niche capability in supercritical
boiler technology; biomass co-firing; modelling; project management;
advanced control systems; and materials. These capacities have
been developed or maintained by the involvement of industry in
major international projects.
Likewise the oil and gas industry in the North Sea has also
allowed the UK to develop geological, engineering, logistics and
PR skills that would be useful in CO2 sequestration
issues. These technologies should be encouraged and involvement
with pilot or commercial scale demonstrations of relevant technologies
should form part of the future strategy.
If a hydrogen-based economy is to be developed, particularly
for transportation, there is little doubt that a CAT programme
will make a significant contribution towards this aim. However
there are other possible alternatives such as the development
of synthetic fuels based on captured carbon dioxide and hydrogen.
Pre-combustion carbon capture combined with integrated gasifier
combined cycle gas turbine (IGCC) technology is likely to emerge
as the eventual natural gas or coal fuelled option that may be
sustainable in a carbon constrained world. This is recognised
by the US Department of Energy FutureGen programme and the European
equivalent (Hypogen), both of which have made significant advances
towards a hydrogen economy. However, the technology is at least
15 years away in respect of commercial viability and so interim
technologies will be required to help fulfil the growth in demand
in the developing world and the replacement plant that will be
required in more mature markets. Two possible options, both of
which could be produced in a carbon capture ready arrangement,
are IGCC and (ultra) supercritical pulverised fuel technologies.
Both provide a significant incremental increase in efficiency
and hence reduction in CO2.