Case Study

Solar power

green energy

8.3.1 Describe how solar power can be harnessed for use in domestic products.

Consider active solar collection and various arrangements of photovoltaic cells (PVs), for example, small individual cells on portable equipment, use of PVs in sustainable building design for hybrid systems, incorporation of PVs into roof design to enhance the sustainability of buildings and also doubling as shelter over car parking areas.

8.3.2 Identify the advantages and disadvantages of solar power.

Consider set-up costs, running costs and maintenance, and continuity of supply.
Fuel source without limit
Very high price
Free main source is the sun
Solar power cannot be created at night.
Does not use fuel therefore does not contribute to the cost of the recovery and transportation of fuel or radioactive waste
Diffuse source – you need large number of solar panels to produce the needed electricity, from there you need a large land spot for this purpose
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There are locations in the world where this energy is collected efficiently. But some of the locations are not with the appropriate sunlight
The equipment needs little maintenance
Depends on the climate conditions
Saving money on long term basis
Large numbers of solar panels (and large land areas) are required to produce useful amounts of heat or electricity
The equipment is easy to install

8.3.3 Describe the design of a solar cooker.

A solar cooker is a simple machine that focuses the rays of the sun into a small area where they can be used to heat food. The sunlight, both direct and reflected, enters the solar box through the glass or plastic top then converting the sunlight into heat energy. This oven uses no power, making it easier to use in areas where electricity and fuel are scarce. Solar cookers work by using parabolic mirrors to concentrate the light at a focal point and heat up that point. This works because every parabola has a focal point at which all lines bouncing off the parabola will eventually reach. The box uses the greenhouse effect and traps the heat inside making temperatures high and sufficient enough for cooking.

external image solarCookersIllustration.gif
external image reflective_cooker.gif
external image Autotracking_Type_Spotlight_Solar_Cooker.jpg
external image solar-cooker---TB_medium.gif

8.3.4 Discuss the importance of solar cooking in sustainable development.

In some rural areas, for example, Nepal, traditional cooking methods involve the burning of biomass fuels and result in indoor air pollution, which is one of the four most critical environmental problems in developing countries. Women and children are more likely to be exposed to indoor air pollution as many women in developing countries spend hours per day cooking near an open fire often with a child strapped to their backs. Indoor air pollution can damage lungs, contributing to acute lower respiratory infections, chronic lung disease, lung cancer, asthma, low birth weight and heart disease. Collection of wood and other biomass fuels contributes to deforestation, with impacts on the water table.

Energy and transport

8.3.5 Compare individual and mass transport systems for sustainable development.

For development in urban areas, mass transport systems are more likely and feasible. A shared vehicle is more efficient than a private vehicle, considering today's oversized cars and light trucks. It is always the green move for an individual to take existing mass transit over their cars, because the transit is running anyway, so there is no incremental cost for carrying one more passenger. Similarly, it is green to carpool in somebody else's car that is going your way. USA Transit efficiency, portrayed in the picture below, can be made greener, reversing the trend of poor efficiency, but transit budgets are planned on decade scales. Ironically in Europe, transit is 2.5 times more efficient, and in Asia, 4 times more efficient, due to their more efficient vehicles.
external image heavyrail.gif
Advantages to mass transit, other than energy efficiency, are:

  1. Provides cheap transportation to those who can't drive or can't afford to, such as children, the elderly and the homeless.
  2. Reduces congestion at rush hour since without transit, roads could never handle the commuter loads in many areas, and would get more inefficient due to heavier congestion.
  3. Reduces the need for parking and allows efficient one-way trips.
  4. It's generally safer against accidents than car travel
  5. Mass transit use electric motors, which moves pollution out of cities and over to power plants.
Further Reading: http://www.templetons.com/brad/transit-myth.html

8.3.6 Discuss the barriers to transition from individual cars to mass public transport systems.

Consider convenience, flexibility, systems integration, for example, park-and-ride systems.

Wind energy

8.3.7 Identify the advantages and disadvantages of small-scale and large-scale wind energy generating plants.-battsengel

Consider small-scale wind energy generating systems, for example, for isolated houses, and large-scale wind energy generating systems for communities and feeding into the national grid.
When making a large or small scale wind energy generating plants, certain advantages and disadvantages can be found. The problem with making a small scale wind energy generating plant is the fact that there is not enough space to install enough windmills to create a substantial amounts of electricity. Also another problem is that they would not be reliable nor would they be consistent as wind is not a consistent source of energy. When discussing a large scale wind farm, the advantage is the fact that with a large number of wind mills, a decent amount of electricity will be generated that could be used to power cities.

8.3.8 Discuss the issues associated with the siting of large wind farms.

Consider impacts on the environment; noise and visual pollution; community lobbying and “not in my back yard” (NIMBY); who pays for the developments; onshore and offshore developments.
Siting issues
Development issues
Need high quality wind resources

Large footprint, small power output
Large footprint, small power output
– Industry rule of thumb has been that a conventional 1.5 MW
turbine design needs turbine spacing of roughly 40 acres of cleared
land/turbine to avoid wind turbulence interference. AWEA
believes 75 acres/turbine required for larger new turbine designs.
To displace energy from New England’s smallest coal unit
(Somerset) would require 167 turbines covering 22 miles of
mountain ridge line.
– As turbines have gotten larger (up to 3.6 MW offered), minimum
spacing requirements have also increased. Need spacing of roughly
8-10 blade lengths (4-5 rotor diameters) between turbines. Newer
larger model designs may require spacing equivalent to 75-100
Wind power — Green but high cost alternative
Wind power — Green but high cost power alternative
– High capital cost
– Low capacity utilization
– Little capacity credit towards reserve margin requirements
– Heavily dependent upon large ratepayer & taxpayer subsidies and mandates to compete against conventional electrical power generation sources
Wind generation environmental/economic benefits. High Cost
High Capital Cost
– Project capital costs have been rapidly escalating due to high turbine demand, weak dollar and rapid increases in labor, materials and supplies
– Capital costs have escalated to $2,100-2,400/kW
Impact on local property values
No air/water emissions but may pose other environmental health & safety challenges
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