The Paris climate summit proposed some stringent targets
for global warming and emissions. These can only be reached if we manage to
engineer a reduction in greenhouse gas output and currently the main means of
achieving this are switching to gas away from coal and deploying renewable
energy and increased nuclear sourced energy.
BGS was asked by Friends of the Earth how we were
responding to the Paris decisions and the BGS Director of Science and Technology has produced a reply which is copied below.
BGS provides scientific evidence on subsurface processes
that are relevant to the economy of the UK, and may be used by government in
support of policy.
Response to Friends of the Earth
Introduction
BGS is an internationally recognised centre
in several sciences that contribute to lower emissions, including carbon capture
and storage, geothermal and the siting of offshore wind farms.
Carbon capture and storage
Predictions like those of the
International Energy Agency’s (IEA) New Policies Scenario
suggest that coal will continue to be used heavily in the future, and will probably
remain the backbone of global electricity generation for many years to come.
This underlines the need for a switch away from coal, and for the coal that is
to be burnt to be used in power stations that are fitted with carbon capture
and storage facilities. A look at three large countries with big coal resources,
China, India and South Africa, illustrates the problem. China is by far the largest coal
consumer in the world, accounting for almost half of global coal use in 2010.
In the IEA New Policies Scenario, China’s coal
demand will increase to over 2850 million tonnes per year by 2020, and
stabilise above 2800 million tonnes until 2035. Coal will continue to provide
more than half of China’s electricity until 2035. Similarly in the New Policies Scenario, South
African coal production, which is mainly for electricity, will peak around 2020
but continue to be high into the future. India is struggling to electrify its
rural economy and it is likely that much of this electricity will come from coal.
In Europe
for 2020, the EU has committed to cutting its greenhouse gas emissions to 20%
below 1990 levels, and further cuts are being decided for 2050. This commitment
is one of the headline targets of the Europe 2020 growth strategy and is being
implemented through binding legislation. Power generation will have to take a
particularly large part in emissions reductions, mainly by focussing on
increasing surface renewables (wind, tidal and solar), nuclear and geothermal
power, but it is likely that carbon capture and storage on fossil fuel power
plants will be important.
Carbon capture and storage may be
particularly important for the 2°C limit set at COP 21, in Paris in December. Most of the
Intergovernmental Panel on Climate Change’s (IPCC) scenarios limiting global
temperature increases to 2 °C include some form of ‘negative emissions’ or
permanent removal of greenhouse gas (GHG) emissions from the atmosphere. Of the
400 IPCC climate scenarios that have a 50% or better chance of less than 2 °C
warming, more than 300 assume the successful and large-scale uptake of
negative-emission technologies. The most popular of these is Bioenergy with
Carbon Capture and Storage (BECCS). BECCS involves growing energy crops for power
stations for electricity and scrubbing out the CO2 in the flue gas for permanent
sequestration in the subsurface.
The main
constraints on BECCS are how much land and resource can be devoted to biofuel
crops, and how much subsurface storage space for carbon dioxide there is. The
first is a difficult problem and not within BGS’ remit. Given the weight that
the IPCC gives to BECCS there is an urgent need to explore the potential
ecological limits to, and environmental impacts of, implementation of BECCS at a
scale relevant to climate change mitigation.
BGS main
research in CCS involves questions over the feasibility of large scale geological
storage of carbon dioxide. Though in Norway two deep subsurface sites 20
million tonnes of carbon dioxide have been safely stored, other geological environments
must be tested and it is vital that more demonstration and full scale schemes
are started, like the Aquistore scheme in south-eastern Saskatchewan where
40000 tonnes of carbon dioxide has been safely stored, and where 1100
tonnes of CO2 are injected per day.
Geothermal
BGS is researching the feasibility of
geothermal heat for residential and civic use including the use of disused mine
workings as a geothermal resource in urban areas, geothermal from deep sedimentary
rocks, and ground source heat pumps. Geothermal could be an important way for
the UK to achieve its goals in emissions reduction.
Although the UK is not actively volcanic,
there is still a substantial resource of geothermal energy at shallow depths
but it is exploited in different ways. The upper 10–15 m of the ground is
heated by solar radiation and acts a heat store. This heat can be utilised by
ground source heat pumps that can substantially reduce heating bills and reduce
emissions. The heat from the sun is conducted downwards into the ground. At a
depth of about 15 metres, ground temperatures are not influenced by seasonal
air temperature changes and tend to remain stable all year around at about the
mean annual air temperature (9–13°C in the UK). Hence, the ground at this depth
is cooler than the air in summer and warmer than the air in winter. This
temperature difference is exploited by ground source heat pumps that are used
for heating and/or cooling of homes and office buildings. There are different
types of systems which can be broadly grouped into closed-loop systems and
open-loop systems.
With increasing depth, the ground
temperatures are also affected by the heat conducted upwards from the Earth's
core and mantle, known as the geothermal heat flow. When combined with the
thermal conductivities of the rocks this allows the prediction of subsurface
temperatures. The UK's geothermal gradient, the rate at which the Earth's
temperature increases with depth, has an average value of 26°C per km. Some
rocks contain free flowing water (groundwater) and so at depth this water will
be warm and can be extracted for use in district heating schemes or for
industrial uses such as heating green houses.
There are also regions in the UK where
the rocks at depth are hotter than expected. This occurs in granite areas
because some granite generates internal heat through the radioactive decay of
the naturally occurring elements potassium, uranium and thorium. Granites have
very little free flowing water, but it is possible to engineer the fracture
system such that water can be made to flow from one borehole to another through
the granite. The extracted hot water is at a sufficiently high temperature to
drive an electricity generating turbine. Parts of Cornwall have geothermal
gradients that are significantly higher than the UK average due to the presence
of granite and have potential for geothermal power generation.
Offshore wind turbines
The Marine Environmental Mapping Programme (MAREMAP) and the Strategic Environmental Assessment (SEA), both of
which BGS is a part, are coordinated efforts to improve seafloor and shallow
geological mapping to establish the ground and geotechnical conditions for many
offshore wind turbines. The
shallow geology can produce impacts and constraints on design, installation and
operation of seabed structures and sub-seabed foundations. Some of these
constraints relate to the variability in the composition and
distribution of Quaternary sediments (at the seabed and in the subsurface)
and bedrock within the first 50 m below the seafloor. Additionally,
other constraints relate to the geological processes that have occurred in the
past or are active today.
As well as
these sciences aimed at direct emissions reduction, BGS is working intensively
on the effects of coming climate change, including on groundwater levels (in the
UK and in Africa), landscape and erosion, and sea level. We are working with a
whole range of partners on how these changes can be forecasted and planned for
so that society is more resilient to change.
BGS is, of
course, interested in all other areas of research into emissions reduction and
climate change science and welcomes discussions on its science strategy.
Best wishes,
Prof Mike Stephenson
Director of Science and Technology, BGS
