Memorandum submitted by the Royal Society
of Chemistry
The Royal Society of Chemistry (RSC) welcomes
the opportunity to comment to the Environmental Audit Committee
on the subject of Reducing Carbon Emissions from Transport.
The RSC is the largest organisation in Europe
for advancing the chemical sciences. Supported by a network of
43,000 members worldwide and an internationally acclaimed publishing
business, our activities span education and training, conferences
and science policy, and the promotion of the chemical sciences
to the public.
This document represents the views of the RSC
and has been put together by our Environment, Sustainability and
Energy Forum. The RSC's Royal Charter obliges it to serve the
public interest by acting in an independent advisory capacity,
and we would therefore be very happy for this submission to be
put into the public domain.
The document has been written from the perspective
of the Royal Society of Chemistry. The chemical sciences and chemical
scientists will play an essential role in driving forward technological
breakthroughs reducing carbon emissions from transport.
The evidence submitted was in the most part
published in an RSC report entitled "Chemical Science Priorities
for Sustainable Energy Solutions" [www.rsc.org/Gateway/Subject/EnvEnergy/].
SUMMARY
Oil derived liquids are at present the most
cost efficient transport fuels and the most efficient energy storage
materials available to us.
A number of different strategies for reducing
carbon emissions from transport are required, the realisation
of which will require contributions from chemical scientists.
In essence technologies are required to make vehicles more efficient
and to provide alternatives to fossil fuels:
— The fuel efficiency of vehicles must
be improved through the use lightweight materials and fuel/engine
additives to increase engine efficiency.
— Development of battery technology
for hybrid vehicles will enable their more widespread acceptability.
— Similar technological challenges
face the development of fully electric vehicles as those facing
the development of hybrid cars, except the electricity should
be generated from renewable or non-carbon based sources to have
a significant effect on carbon emissions.
— Biofuels are a renewable, carbon
neutral source of vehicle power but many technological challenges
must be overcome for their widespread use to be practicable.
— Hydrogen power vehicles too require
many technological challenges be overcome before they can become
a reality.
— Reducing carbon emission from air
transport too presents challenges: use of lightweight materials
will yield improved efficiency.
STATE OF
PLAY
In spite of current concerns about the constrained
oil supply and high cost, most scenarios for the next 20 to 50
years suggest that the world's growing demand for energy will
be primarily met by fossil fuels. Currently, about 74 million
barrels of oil are consumed every day, mostly for transport, which
is the sector where oil is most suited as the primary energy carrier,
and where substitution is arguably most difficult. By 2020 this
is predicted to have increased to about 110 million barrels per
day (bpd). The demand for oil for transportation in the Asia Pacific
countries is growing at 3.5% per annum from a current demand of
about 18 million bpd compared to growth in Europe of just 0.5%
from a demand of about 15 million bpd.
Trends in vehicle design are being driven by
the need to increase efficiency and reduce CO2 emissions.
In 1997 there were 600 million vehicles on the world's roads,
with engines operating at efficiencies of 10-25% for petrol and
15-35% for diesels. Transmission, road and other losses reduce
efficiency significantly for the overall vehicle. Vehicle engineers
around the world are currently chasing every lead with a view
to achieving the goal of improved fuel efficiency coupled with
reliability and affordability. It is generally accepted that the
customer is unprepared to compromise his or her expectation of
vehicle performance, reliability or cost, so technological improvements
are necessary alongside environmental developments.
Multidisciplinary teams including chemists and
chemical engineers have already achieved significant improvements
in the operation of the internal combustion engine by developing
direct injection spark ignition systems and small diesels with
more efficient turbo chargers. Efforts to improve engine efficiency
by variable valve timing, cylinder deactivation, to reduce engine
displacement during normal driving, reductions in engine friction
and accessory loads, and sophisticated engine management systems
all show promise.
The chemical sciences have been, and continue
to be, pivotal in the development of systems that offer significant
improvements to fuel and exhaust systems in vehicles; this has
been demonstrated through the development of unleaded petrol (eradicating
harmful lead additives), detergent additives (that have increased
fuel economy and increased engine lifetime), oxygenated fuels
(that improve fuel efficiency) and catalytic converters (to reduce
harmful carbon monoxide, volatile organic compounds and NOx emissions).
FUTURE CHALLENGES
Reducing vehicle weight
Vehicle performance can be considerably improved
by reducing weight through the use of lighter construction materials.
The past 20 years has seen a steady decrease in the amount of
iron and steel in a typical family car with a corresponding increase
in the amount of polymer composites, aluminium and even magnesium.
Increased attention to the various bulk, surface and compositional
chemistry aspects of the forming, joining and recycling of these
materials, to reduce manufacturing, design and assembly costs
without compromising safety, will greatly enhance the use of lightweight
materials in vehicle construction. This will require polymer and
synthetic chemists to create new structural materials and designs
to reduce radically vehicle weight without compromising safety.
Such materials are also required to conform to legislation such
as the EU ELV (End of Life Vehicles) directive and thus be demonstrably
recyclable.
Systems engineering approach
A further fruitful area of research might be
to consider personal mobility as a systems engineering problem
consisting of the engine and fuel, the transmission system, the
vehicle itself including the wheels, the road surface and construction,
the refuelling infrastructure and the eventual recycling of the
components. Much of this will require a deep understanding of
the chemistry and chemical engineering aspects of the fuels, their
combustion characteristics, the engine and vehicle shell materials,
the control systems and sensors required, transmission and energy
storage and the re-use of the component materials. The task of
creating a sustainable transport system when cars will continue
to be the preferred means of personal mobility in the urbanised
regions of the developed world is considerable and will require
the ingenuity of chemists as well as engineers.
Hybrid vehicles
In the past few years some vehicle manufacturers
have introduced hybrid drive trains into the market place. Various
arrangements are possible but the combination of a smaller gasoline
or diesel engine coupled to electric batteries and electric drive
motors, together with recovery of the vehicles momentum through
regenerative braking, have led to dramatic increases in energy
efficiency. Further improvements in this approach will require
lightweight construction materials and technology, efficient low
emission engines and improved battery or alternative energy storage
technology. Introduction of hydrogen fuel cells, alone or in hybrid
configuration with a battery, offer the possibility of removing
the car from the environmental debate, as well as allowing the
use of renewable and sustainable fuels.
Electric vehicles
Fully electric vehicles have a number of issues
in common with hybrid vehicles in so much as energy storage technology
(eg battery technology) is absolutely critical to success. Electric
vehicles differ from hybrid vehicles in that there is no back
up supply, so when the battery runs down, the vehicle stops. Therefore
the range of the vehicle is dictated by battery technology available
and also the weight (and thus efficiency) of the vehicle is related
to the number/size of the batteries required. For low emission
vehicles the electricity must be supplied through low emission
electricity sources, such as that derived from, renewables, nuclear
power or fossil fuels coupled with carbon capture and storage
technology. Therefore there is a need for an infrastructure to
supply "charging points" for electric vehicles. An electric
vehicle supplied by low carbon technologies would in theory be
a very low carbon emission vehicle.
Biofuels
Today, biomass provides about 20% of Brazil's
primary energy supply, with much of this being alcohol fuel, which
accounts for about 30% of gasoline demand. In early 2003, the
European Commission issued a directive promoting the use of biofuels
for transport, setting out two indicative targets for EU member
states—2% biofuels inclusion in the fuel pool by December
2005 and 5.75% by December 2010. The UK is currently not on track
to meet the 2010 target.
The relatively low conversion efficiency of
sunlight into biomass means that large areas of arable land would
be required to allow a significant amount of the existing fuel
pool to be substituted with biofuels. Scenarios developed for
the US and EU indicate that short term targets of up to 6% displacement
of fossil fuels with biofuels appear feasible using conventional
biofuels. A 5% displacement of gasoline in the EU would require
about 5% of available cropland to produce ethanol and 15% to produce
diesel (land requirements for diesel are higher than for ethanol
because of lower yields of liquid fuel per hectare). Kheshgi et
al estimate that the equivalent of 12% of US cropland would be
required to produce enough ethanol to replace the energy content
of 10% of the US gasoline consumption in 1990. However, if all
the carbon dioxide emissions associated with the production, harvesting,
and conversion of corn to ethanol were to be offset, the land
area required would be nearer to 50% of available cropland.
Biofuels are more expensive than conventional
transport fuels, but improved conversion technologies will broaden
the range of feedstock. For example, the cost effective hydrolysis
of lignocelluloses (for example wood or straw) would considerably
increase the source of biomass for bioethanol production to include
woody and grass crops as well as bio-waste. Work is underway in
a number of countries and in particular the US to reduce the cost
of converting cellulose to sugars, although a considerable amount
of biomolecular and chemical engineering is required in order
to achieve commercially attractive prices. Recent work in this
area has led to the concept of a "bio-refinery" similar
to a petroleum refinery, which would use the whole of the biomass
feedstock to produce a number of products in addition to biofuels,
such as high value chemicals and co-generated electricity. Encouragement
by US government and EU funding and targets for inclusion of biofuels
in the transport fuel pool should see rapid developments in this
area. There is considerable research interest in the UK in the
area of the bio-refinery.
Gasification and thermochemical technologies
are receiving increased attention as methods of converting biomass
into transport fuels. Gasification to syngas (a mixture of hydrogen
and carbon monoxide) enables the production of a variety of fuels
including methanol, ethanol, dimethyl ether and synthetic diesel.
Hydrogen vehicles
On-board storage of hydrogen is posing significant
obstacles to delivering hydrogen-powered vehicles. Hydrogen is
a gas at room temperature and therefore needs to be liquefied,
compressed or stored in some other way to have enough onboard
to travel a reasonable distance. Nearly all of today's prototype
hydrogen vehicles use compressed gas, but this is relatively bulky.
Liquid hydrogen could provide an ideal way to transport hydrogen,
but the boiling point of hydrogen at -253°C means that this
storage method would be extremely energy intensive, requiring
considerable energy to keep and maintain such low temperatures.
Other advanced storage materials are being developed, such as
carbon based adsorbents (carbon nanotubes) and metal hydrides.
However, the high temperatures and pressures required to liberate
H2 and slow-H2 release are posing serious obstacles to these storage
materials.
There are also significant economic considerations
surrounding the cost of fuel cells versus the internal combustion
engine, with the latter typically costing $30 for each kilowatt
of power it produces while fuel cells cost a hundred times more.
Technical challenges such as making fuel cells rugged enough to
withstand the stress of driving, reducing their size and weight
while increasing power density and fuel flexibility also still
exist. In the interim, while fuel cell technology is preparing
for mass commercialisation, it is likely that more and more hybrid
electric vehicles will be deployed, offering significant improvement
in terms of energy use and significant reductions in carbon emissions
in comparison to the conventional internal combustion engine.
Air travel
Air transport is receiving increasing attention
because of environmental concerns linked to CO2 emissions,
air quality and noise. Continuing atmospheric chemistry research
into the impact of aircraft emissions in the upper troposphere
(extends from about 14 to 18 km) and lower stratosphere (extends
from the troposphere to about 50 km) is required. To reduce emissions,
designs with reduced weight will benefit fuel economy and efficiency.
Embedded sensors and controls (in intelligent gas turbine engines)
could reduce noise, emissions and costs through more effective
diagnosis and maintenance processes. New materials are required
(eg low-cost composites, corrosion-resistant, damage-tolerant
alloys and smart materials) to reduce manufacturing, life-cycle
costs and reduce travel time, whilst advanced coatings for the
next generation of gas turbine engines are required for improved
fuel efficiencies and emission reductions. There is a real need
for innovative work in this area. Multidisciplinary teams of chemists
and engineers are needed to develop viable solutions.
February 2006
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