Energy Supply Mitigation Opportunities
Sources: Climate Change 2001 Synthesis report pages 323-4, Climate
Change 2001 Working Group 3 Mitigation Section 3.8.4
If we are to stabilize greenhouse gas emissions and meet our Kyoto
Protocol commitments, we need to change our sources of
energy.
Fossil fuels continue to dominate heat and electric power production.
Electricity generation produces 37.5% of global carbon emissions.
This means 2100 MtC (Megatonnes of carbon). With no carbon emission
policies, emissions grow to 3500 for 2010 and 4000 for 2020.
There are several technologies which can contribute to lower
emissions.
Combined Cycle Gas Turbines (CCGTs): These are the dominant
option for new electric power plants where there is adequate
natural gas supply. They are low cost and are about 60% efficient
in converting the fuel into electricity. This is because the
waste heat from the gas turbine exhaust is captured and used
to generate electricity by a steam turbine. So in a CCGT plant,
electricity is generated by both gas and steam turbines.
Integrated Gasification Combined Cycle (IGCC) systems: These
plants first gasify coal or other fuel. They have similar efficiency
and low cost as the CCGTs but can use fuels such as tar and biomass
fuels like wood. Their efficiency in converting fuel to electricity
is about 51%. These systems can possibly reach over 60% efficiency
as the technology improves. Another promise of this technology
lies in the gasification process. The gas from the gasifier can
be converted into a stream of H2 and CO2. The CO2 can be removed
for disposal and the H2 can be used in fuel cells.
Cogeneration: Combined heat and power (CHP) can use up
to 90% of the fuel energy for heating and power generation. These
systems are used industrially and commercially for space heating
and manufacturing needs.
Fuel Cells: There are many types of fuel cells, but they
all have the same advantages over gas turbines. They are smaller
but have similar conversion efficiency, basically zero GHG emissions,
lower maintenance costs, and less noise. The internal fuel is
hydrogen. Some fuel cell types can use carbon monoxide, methanol,
natural gas or coal if these fuels are converted to hydrogen
at the plant. Other fuel cell designs convert fuel to hydrogen
internally as part of the technology.
Nuclear Power: The life cycle greenhouse gas emissions per kWh
from nuclear power plants are two orders of magnitude lower than
those of fossil-fuelled electricity generation and comparable
to most renewable energy sources. This makes it an effective
GHG mitigation option. It has become cost effective to extend
the lifetime of existing nuclear reactors. However, other than
in Asia, there are few new plants being built. Instead, the effort
is in developing intrinsically safe and less expensive nuclear
reactors. The goal of the new nuclear power technology research
is to reduce public concern about safety, storage of nuclear
waste and proliferation of nuclear weapons.
Renewable Energy:
Hydropower: Hydroelectricity is the most developed renewable
resource worldwide. Construction of new hydropower projects has
slowed down for several reasons; few available major sites, high
initial costs, environmental impacts (e.g. flooded fertile land)
and social costs (e.g. uprooting communities). Numerous small
scale hydro schemes with low environmental impacts continue to
be developed globally.
Biomass: In addition to energy crops, biomass resources
include agricultural and forestry residues, landfill gas and
municipal solid wastes. Since biomass is widely distributed,
it has good potential to provide rural areas with a renewable
source of energy. One current biofuel is ethanol. It is made
by fermenting a source of sugar. Ethanol production is commercially
undertaken in Brazil from sugar cane and in the USA from maize
and other cereals. It is used as a straight fuel and/or mixed
with gasoline at 5%-22% blends.
Wind Power: There has been a recent rapid growth of wind turbines which
has been greater than 25% per year. The cost of wind turbines
continues to fall as more new capacity is installed. The trend
follows the classic learning curve and further reductions are
projected. In high wind areas, wind power is competitive with
other forms of electricity generation.
Solar Power: The amount of solar radiation intercepted by the
earth may be high but the market potential for its use a central
power generation is low for several reasons:
It has relatively high costs. There is a time variation from
daily and seasonal fluctuations, so the energy has to be stored.
There is great geographical variation, i.e. areas near the equator
receive approximately twice the annual solar radiation than areas
at 60o latitudes. Large-scale generation from direct solar energy
can require significant amounts of equipment and land.
The use of photovoltaic cells is increasing. The costs
of photovoltaics are slowly falling as more capacity is installed.
Solar power is proving competitive in niche markets, and has
the potential to make substantially higher contributions in the
future as costs fall. Photovoltaics are often installed at the
point where the electricity is used, such as buildings. This
can give a competitive advantage over power from central power
stations to offset higher costs.
- In your group, research one of the technologies for reducing
GHG emissions.
- Create a commercial story board or magazine ad for the technology.
- Your commercial or ad should contain three key messages to
the viewer.
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