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Chapter 3

Direct Solar Energy

Lifecycle GHG Emissions of Photovoltaic Technologies

250

Lifecycle GHG Emissions [g CO eq /kWh]

2

Estimates:

124

30

56

12

13

4

6

2*

1

References:

26

9

15

3

3

1

2

2

1

as well as discharge of pollutants related to today’s steel production technology (Felder and Meier, 2008).

India (Rajasthan and Gujarat states), Australia, Chile, Peru, Mexico and south-western USA.

The cost of land generally represents a very minor cost proportion of the whole plant. A 100-MW CSP plant with a solar multiple of one (see Section 3.3.4) would require 2 km2 of land. However, the land does need to be relatively flat (particularly for linear trough and Fresnel sys- tems), ideally near transmission lines and roads for construction traffic, and not on environmentally sensitive land. Although the mirror area itself is typically only about 25 to 35% of the land area occupied, the site of a solar plant will usually be arid. Thus, it is generally not suitable for other agricultural pursuits, but may still have protected or sensi- tive species. For this kind of system, sunny deserts close to electricity infrastructure are ideal. As CSP plant capacity is increased, however, the economics of longer electricity transmission distances improves. So, more distant siting might be expected with according increases in transmission infrastructure needs. Attractive sites exist in many regions of the world, including southern Europe, northern and southern African countries, the Middle East, Central Asian countries, China (Tibet, Xinjan),

In the near term, water availability may be important to minimize the cost of Rankine cycle-based CSP systems. Water is also needed for steam-cycle make-up and mirror cleaning, although these two uses represent only a few percent of that needed if wet cooling is used. However, there will be otherwise highly favourable sites where water is not available for cooling. In these instances, water use can be substan- tially reduced if dry or hybrid cooling is used, although at an additional cost. The additional cost of electricity from a dry-cooled plant is 2 to 10% (US DOE, 2009), although it depends on many factors such as ambi- ent conditions and technology, for example, tower plants operating at higher temperatures require less cooling per MWh than troughs. Tower and dish Brayton and Stirling systems are being developed for their ability to operate efficiently without cooling water.

In a manner similar to that for PV, NREL conducted an analogous search for CSP lifecycle assessments. Figure 3.15 displays distributions

*same value

Figure 3.14 | Lifecycle GHG emissions of PV technologies (unmodified literature values, after quality screen). See Annex II for details of the literature search and citations of literature contributing to the estimates displayed.

225

200

175

150

125

100

75

50

25

Maximum

75th Percentile Median

25th Percentile Minimum

Single Estimates

0

Cadmium Selenide Quantum Dot (QDPV)

All Values

Ribbon Silicon

Cadmium Telluride (CdTe)

Nano-Crystalline Dye Sensitized (DSC)

Concentrator

Mono-Crystalline Poly-Crystalline

Silicon (m-Si)

Silicon (p-Si)

Amorphous Silicon (a-Si)

371

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