Environmental Impact

In this section the environmental impact of the above-said non-conventional (renewable) sources of energy would be discussed in terms of equivalent carbon dioxide emission into the atmosphere. Figure 3.1 shows the equivalent CO2 emission for different energy sources for direct and indirect carbon dioxide emissions. The former is used for the emission during the operation whereas the latter is responsible for CO2 emission other than the operation, say, during the installation of a system.

c 150

Biomass

1 Direct emission □ Indirect emission 410

Hydro

Wind

Renewable energy sources

Solar

Fig. 3.1 Worldwide CO2 emission into the atmosphere from various energy sources (data from IAEA, 2001).

It can be seen that the direct emissions per kWh electricity generation from the wind, biomass, hydro, and solar are 37, 16, 11, and 30 g/kWh and indirect emissions are 116, 410, 75, and 279 g/kWh, respectively. Some of the renewable technologies, i.e., hydro and wind, are competitive with conventional technologies as they have better efficiencies. Table 3.1 shows that the conventional technologies like coal and gas are more economical for per kWh electricity generation but they pollute the environment more. However, the price of per kWh electricity generation for coal and gas is lower than the renewable energy sources which is also given in Table 3.1.

Table 3.1 Mfean price, efficiency of electricity generation, and average greenhouse gas emissions expressed as CO2 equivalent for individual energy generation technologies.

Energy Sources

US$/kWh

Efficiency (%)

gCO2/kWh

Photovoltaic

0.24

4-22%

90

Wind

0.07

24-54%

25

Hydro

0.05

>90%

41

Geothermal

0.07

10-20%

170

Coal

0.042

32-45%

1004

Gas

0.048

45-53%

543

On the other hand the renewable energy sources are either cost-effective (for example, wind, biomass, and geothermal) or less polluting the environment. Further, the electricity generation efficiency of the different technologies is given in the same table and it is clear that some renewable sources (for example, wind and hydro), which possess better efficiency, are competitive with the conventional technology (coal, gas, etc.).

The greenhouse gases are responsible for global warming and climate change. Other than CO2 some other pollutants like SOX, NOX, and CFCs, etc., also affect the environment adversely. Some other environmental problems are acid rains, ozone layer depletion, etc. Former is caused due to SOX and NOX whereas latter is due to CFCs, CO, and the unbent hydrocarbon from the exhaust of rockets.

Table 3.2 Sustainability indicators for some renewable energy sources.

Photovoltaic

Wind

Hydro

Geothermal

Price

4

3

1

2

CO2 emission

3

1

2

4

Availability and limitations

4

2

1

3

Efficiency

4

2

1

3

Land use

1

3

4

2

Water consumption

2

1

3

4

Social Impact

2

1

4

3

Total

20

13

16

21

Evans et al. (2009) have given some sustainability indicators for some renewable technologies; each technology was ranked from 1 to 4 according to the corresponding indicator as shown in Table 3.2, with 1 being the best technology for that indicator. The average and range were considered together, where values were quantifiable, as there was often significant overlap between values.

Some impact categories, such as availability and limitations as well as social impacts that are unable to be quantified, were assessed qualitatively. In case of limitations, hydro was chosen as the least limited, due to its ability to provide base load power, number of suitable sites worldwide, and flexibility of operation. Wind was considered the second best for similar reasons. Geothermal is slightly more limited worldwide, with less suitable locations. Solar is considered the most limited, since excess power during daylight hours is not yet able to be stored enough to provide adequate power during off sunshine periods (nights and on cloudy days). As far as social impacts were concerned, wind was allocated the least negative social impacts, due to its benign nature. Solar was second, as careful management during manufacture and proper site selection mitigate its potential negative impacts, and geothermal was third due to increased seismic activity and pollution potential. Hydro had the largest impact, primarily due to the large number of people and animals displaced during dam inundation. The ranking in Table 3.2 suggests electricity production from wind is the most sustainable followed by hydropower and then solar and geothermal were found to rank the lowest from the four non-combustion renewable energy technologies (Evans et al., 2009). This ranking was provided for the global international conditions, while each technology can be significantly geographically affected. For a certain geographical location, some of the listed sustainability indicators may become more important than others.

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Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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