BP Educational Service
Science at Work
Carbon capture and storage
Carbon from the past
2.How did the tiny marine organisms trap
carbon dioxide?
Oil and gas began their long process of formation
many 10s to 100s of millions of years ago. One
period when this happened was about 200–145
million years ago in the Jurassic period.
Just as oil and gas were formed from buried marine
creatures, coal can form when land plants die and
are buried. The coalfields of the UK and Europe
formed over 300 million years ago in the
Carboniferous period. Plants from huge forest
swamps locked up carbon when they died and
were converted into deeply buried coal.
Conditions on Earth were very different then. It was
much warmer and there was no ice cover in the
polar regions. Sea levels were much higher than
today and much of the planet was covered in deep,
tropical seas.
These processes continue today. The oceans
still contain vast quantities of plankton and algae.
The land still has huge forested areas. All form
part of a wider process called the carbon cycle.
1.Why was the sea level higher during the
Jurassic period?
The carbon in the oil and gas we use today was
trapped by algae and plankton living in these
tropical seas.
The atmosphere
contained very
high levels of
carbon dioxide (CO2).
CO2 dissolves easily
in water.
Algae and
plankton thrived
in CO2-rich, warm
seawater near the
surface. They
photosynthesised
in the sunlight, just
like modern plants.
These tiny
creatures died
and sank to the
seabed. They were
buried by sand
and mud.
View of earth from space
1
Over millions
of years, high
pressures and
temperatures
deep underground
transformed the
dead matter into
oil and gas.
Today, this
oil and gas
provides most
of our energy.
It contains
carbon that was
trapped millions
of years ago.
The carbon cycle
Carbon dioxide in the atmosphere
Photosynthesis
Respiration
Decay
Combustion
Fossil fuels
Burial and
geological
processes
Death
Animals
Feeding
Dead plants
and animals
Respiration
Combustion
Plants
Death
The carbon cycle
3.Why is the atmosphere called a ‘sink’
for carbon?
All known life forms are based on carbon. It is a key
component of most organic material, from fossil
fuels to your DNA. But almost all of the Earth’s
carbon is ‘locked up’. Sedimentary rocks, such
as limestone and chalk, may hold as much
as 99.999% of the Earth’s carbon.
The carbon content of the atmosphere has always
changed slowly. However, when people burn
fossil fuels, stored carbon is released into the
atmosphere as carbon dioxide. It is added back
into the carbon cycle. Most scientists agree that
this is causing more rapid increases in atmospheric
carbon than has ever been seen in the past.
The tiny fraction that is left constantly flows
through the Earth’s environment.
The carbon cycle is made up of:
– ‘carbon sinks’, where carbon is stored for long
or short periods of time, e.g. the atmosphere
4. How have fossil fuels acted as a carbon sink?
Adding carbon to the atmosphere matters because
carbon dioxide is a greenhouse gas. Greenhouse
gases trap the Sun’s heat. The concentration of
these gases has increased in recent decades and
this has contributed to global warming. Scientists
do not know how this will change the carbon
cycle, or how global warming will affect life on
Earth. But most are convinced that the increase is
due to burning fossil fuels.
– processes that exchange carbon
between sinks.
Adds carbon to the
atmosphere
Removes carbon from
the atmosphere
Combustion
Decay
Respiration
Photosynthesis
(Geological processes also add or remove carbon.
These processes are incredibly slow. Oceans also
contain huge amounts of dissolved carbon dioxide.)
Carbon dioxide is also absorbed by the oceans,
which are slowly becoming more acidic. This could
have a significant effect on marine life.
2
The chemistry of combustion
Coal, oil and gas are all hydrocarbons and are
important energy sources. Their energy is released
by combustion. Combustion is a chemical
reaction in which the molecules of a fuel react with
oxygen in the air. Coal, oil and gas are examples of
fuels. Combustion always produces oxides, and
releases energy.
Incomplete combustion happens when
there is not enough oxygen:
Complete combustion happens when plenty of
air is available:
When methane burns in limited oxygen
we can write:
hydrocarbon +
oxygen
hydrocarbon +
insufficient oxygen
2CH4 + 3O2
carbon dioxide +
water + energy
CH4 + 2O2
carbon monoxide +
water (+ less energy)
2CO + 4H2O
This is just one example of incomplete
combustion. Sometimes soot is formed, which
is made of pure carbon.
CO2 + 2H2O
6. Write a balanced equation for incomplete
combustion, where carbon is also produced.
(Remember that water is the oxide of hydrogen –
the equation shows this.)
Incomplete combustion has many
disadvantages, e.g.:
– Carbon monoxide is toxic, and can kill
– The reaction is less efficient, so less energy
is released
Oil burner
Iced water
Oil and gas processing scientists create advanced
fuels that combust more easily. They work with
car manufacturers to help them design better
engines. These engines release more energy,
and less carbon monoxide and soot.
Limewater
Apparatus for identifying the products of combustion
5. How does this apparatus identify the
products of complete combustion?
3
Capturing carbon
As the world’s population grows and develops,
demand for energy is increasing rapidly. The world’s
coal reserves could last for more than 150 years,
much longer than oil and gas. This coal could help
meet increasing demand for energy.
However, burning coal produces large amounts
of carbon dioxide. How can countries use these
reserves, without increasing carbon dioxide
concentrations in the atmosphere?
Many scientists working in universities and in
the power generation and oil and gas industries
are pioneering Carbon Capture and Storage
(CCS). CCS captures the carbon dioxide where
it is produced – at power stations. It is then
transported by pipe and stored deep underground.
A BP carbon capture and storage facility in Algeria
7.Why might CCS be useful for power
stations, but not for cars?
CCS has many advantages:
– It can prevent carbon emissions from
rejoining the carbon cycle and contributing
to global warming
– It will last for a long time: there is far more
‘storage’ available than we need, and the longer
the carbon dioxide remains underground,
the more securely it becomes trapped
– The carbon dioxide can be injected into oil and
gas fields for storage and this can help extract
more oil and gas
‘CO2 storage in
geological formations
could provide a major
opportunity for holding
down CO2 levels
in the atmosphere.’
8.Why would existing oil and gas fields be
good places to store carbon dioxide?
BP and its partners are testing CCS to make sure
it is effective and reliable. Today, BP’s oil and gas
fields provide us with energy. In the future, they
could also store the carbon dioxide that this
energy produces.
Leader, BP CO2 storage
4
Removing carbon from coal
Carbon Capture and Storage (CCS) can trap the
carbon that power stations emit. This carbon could
also be removed from the fuels that the power
stations use.
At Abu Dhabi in the United Arab Emirates, BP
and its partner Masdar are planning a new power
station. Just like many power stations around
the world, this new station will use natural gas.
But it will not burn the gas directly as fuel.
Instead, the gas will be cleaned to remove
impurities such as sulphur. It will then be
treated before it is used in the power station.
The carbon capture and storage process © CO2CRC
The natural gas reacts with
oxygen and steam to produce
‘syngas’, a mixture of hydrogen
and carbon monoxide.
The components of the syngas are
further processed and separated.
The hydrogen is burned
in the power station:
2H2 + O2
The carbon dioxide is compressed.
2H2O
The carbon dioxide is piped offshore.
This provides almost carbon-free
energy for homes and businesses.
The carbon dioxide is stored
deep underground in a carefully
chosen geological formation.
5
Removing carbon from coal
The proposed Abu Dhabi power plant
The Abu Dhabi plant will use only the hydrogen
to generate power.
9.Why will the Abu Dhabi plant’s process
reduce the effect of power generation
on the carbon cycle?
The carbon dioxide that is extracted from the gas
will be stored underground in the oil reservoirs
deep under Abu Dhabi. The rock types, and the
shape of the formation, will secure this carbon
dioxide forever, in practical terms.
‘It will be many years until
the impact of renewable
energy solutions is felt at
scale, hence we need energy
solutions now to help us
bridge that time gap without
adding to CO2 emissions.’
10.How will storing the carbon dioxide from
natural gas make the Abu Dhabi station a
low carbon power station?
Up to 90% of the carbon dioxide from the natural
gas fuel is expected to be captured. Around 1.7
million tonnes of carbon dioxide are expected to
be captured each year – a carbon saving equivalent
to taking every car in Abu Dhabi off the road.
Director of CCS technology,
BP Alternative Energy
6
Glossary
Carbon cycle – the process by which carbon
is exchanged between the Earth’s oceans,
atmosphere, rocks and life.
Carbon sink – a part of the Earth that can
temporarily store carbon in some form or another;
sinks include the atmosphere, biomass, rocks and
the oceans.
Combustion – the chemical reaction between a
fuel and oxygen that creates oxides and releases
energy.
Decay – the breakdown of dead plants and
animals into simpler substances by bacteria and
other micro-organisms.
Fuel – a substance or material that can be burned
(combusted) to release energy.
Oxide – a compound of oxygen and another
element.
Photosynthesis – the process by which plants
convert light energy into chemical energy; carbon
dioxide and water combine to produce oxygen
and glucose.
Respiration – the process by which cells in living
organisms obtain energy; glucose is converted
into carbon dioxide and water.
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