Energy Supply Sector

7.1.2.2.f

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.

Co-generation: 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.

ACTIVITY

• 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.