In the past couple of
years, several
developed countries
have begun investing
in small-scale pilot
projects to figure out
the best way to take
CO2 out of power plant
emissions and
store it underground.
Awareness of carbon footprint
has been increasing with time
as reasons for some of the
disasters are converging to the view
that there is a strong need for it to
secure the future generation. There is
a push to cut the amount of carbon we
release into the atmosphere,
solutions usually focusing on how to
reduce our human contribution by
adopting slightly diff life style. Much
analysis confirms that major
contribution to Carbon emission is
from power system and
predominantly from power
generation. In US 40 per cent of
carbon emissions are contributed by
power.
The Swedish utility Vattenfall
carried out a study of full life cycle
emissions of nuclear, hydro, coal,
gas, solar cell, peat and wind which
the utility uses to produce electricity.
The net result of the study was that
nuclear power produced 3.3 grams of
carbon dioxide per KW-Hr of
produced power. This compares to
400 for natural gas and 700 for coal
(according to this study). The study
also concluded that nuclear power
produced the smallest amount of CO2
of any of their electricity sources.
Developing countries like India
with large percentage of coal filed
power plants have to focus on
reducing the carbon emission. Is it
possible to replace carbon fuels i.e.
coal and oil/diesel with renewable
sources like solar, wind, biofuels, to
some extent yes, we should keep
doing it, but the contribution is much
less as we still have approximately 56
percent of coal fired power
generation. According to a recently
released report by India's Planning
Commission, by bringing in new
technologies like super-critical
thermal power plants, gas-fired
power plants and low-carbon power
technologies like nuclear, hydro and
renewable energy, Indian power
sector's carbon footprint can reduce
significantly , approximately 21
percent by 2020.
This situation is not going to
change drastically for years to come.
India will not be going to suddenly
shut down all their old/new coal
power plants and the factories. Solar
and wind may be today's sexy new
energy sources, but coal is the
fastest-growing fuel in the world,
boasting twice the known gas
reserves and three times the known
oil reserves.
Many governments with large coal
based power plants are publishing the
strategy in dealing with reducing
carbon emissions from fossil-fuelled
power stations. In UK, the strategy
report considers Carbon Abatement
Technologies (CATs) and identifies
three CATs that might be deployed:
- Higher efficiency conversion
processes
- Fuel switching to lower carbon
alternatives
- CO2 capture and storage (CCS).
Thus in India too one can surely
think of reducing the carbon emission by employing the use of advanced gasification plants. By using
gas powered electricity generation, the carbon footprint can
be reduced to around half that of coal, because gas has a lower
carbon content than coal. Also deploying distributed control
system monitoring these gases and also controlling them etc.,
thus focusing on conversion efficiency which is ongoing
process in our existing and new plants.
Second possibility is switching on to lower carbon
alternatives like wood chips, coconut shells, sunflower husks,
rice husks and grasses along with coal in a coal fired power
plants. Drax, the UK’s largest power station, powered by coal,
and providing up to 7 percent of the UK’s electricity, has
launched a project to replace 10 percent of the coal it uses with
biomass.
Basically, a powder made of materials such as wood chips,
sunflower husks and grasses will be injected into the coal-fired
furnaces, thus reducing the amount of coal burnt on a daily
basis. As biomass is regarded as carbon neutral, this also
reduces the overall amount of CO2 emissions from the power
plant, helping Drax on the way to their target of reducing their
emissions by 15 percent by 2012. The amount of biomass
injected could be increased, reducing emissions even further.
However, one question remains how we are going to control
this large carbon emission when 56 percent generation still
depends on the coal and diesel.
One technology which many governments in west begun to
pay more attention is carbon capture and storage (CCS) — a
process that traps CO2 produced by factories and gas or coal
power stations and then stores it underground. Many of these
panels on Climate Change predict that CCS could contribute
between 10 percent and 55 percent of the cumulative
worldwide carbon-mitigation effort over the next 90 years.
The International Energy Agency recommends that CCS is the
most important single technology for CO2 savings in power
generation and industry, and will need to account for about
one-fifth of the carbon-mitigation effort this century —
reducing carbon emissions as much as renewable energy
sources will.
One disadvantage is the technology is commercially not
available, though world's first CCS coal plant opened in
Germany; the operation captures approximately 240 tonnes of
CO2 a day and trucks it to an empty gas field where it is
injected into an underground aquifer. Other concern is to run a
CCS integrated coal power plant needs 40 percent more
energy than a regular coal plant and however, CCS could
potentially capture about 90 percent of all the carbon.
In the context of technology, it is not nascent; Oil companies
started injecting CO2 into underground oil-bearing strata in
the U.S. however, the target was enhanced oil recovery,
allowed them to extract up to two-thirds more oil than by
simply pumping the fuel to the surface increased efficiency in
exploration.
The first country to store CO2 underground deliberately to
keep it out of the atmosphere was Norway. When the
government there introduced a carbon tax in the early 1990s,
energy giant Statoil began capturing the CO2 from its naturalgas
platform in the North Sea and pumping it into a salinefilled
sandstone layer under the seabed. Since 1996, the operation has cut Norway's CO2 emissions by almost a million
tons a year, or about 3 percent of the country's 1990 CO2
emissions. Other projects have followed, including one on the
U.S.-Canada border that has been pumping CO2 from a coal
plant into an oil reservoir for the past decade.
The question is whether the technology can be scaled up and
used on power plants everywhere. In the past couple of years,
governments in Australia, Canada, China, Europe, Japan and
the US have begun investing in small-scale pilot projects to
figure out the best way to take CO2 out of power-plant
emissions and store it underground. Every government has
earmarked fund, e.g. European Union has set aside $1.5
billion to build seven CCS pilot projects; US has promised
millions of dollars for trials and a large-scale CCS power
plant, the Australian government is spending almost $100
million a year on the GCCS. Large-scale CCS deployment is
still few years away, today world is better off focusing on
renewable energy.
Some environmental groups say that, just like nuclearpower
stations, CCS technology leaves behind a dangerous
waste material that has to be stored. Greenpeace says there's
no way of knowing that carbon will stay underground for
centuries and has called CCS "unproven, risky and expensive.
The problem we have with power today is that we need it, and
more of it, and we need it to be reliable too. There is no immediate
solution other than that mentioned above that can enable us to
replace current CO2 emitting power stations with so clean and
100 percent reliable solutions, or unless we install millions of
wind turbines, solar panels and tidal flow generators, completely
ignoring the sometimes reasonable cries of those who believe they
have a negative effect on the environment. What’s more, these
solutions still have their issues - no wind, no sun, up and down tides
don’t make for regular supplies.
(Prakash Nayak is the Chairman of the Power Panel, The
Institution of Engineering and Technology (IET).)