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CLOSE THIS BOOKRenewable Energy Technologies: A Review of the Status and Costs of Selected Technologies (WB, 1994, 184 p.)
VIEW THE DOCUMENTAnnex 1. Cost calculations and currency adjustments
VIEW THE DOCUMENTAnnex 2. Costs of ethanol production
VIEW THE DOCUMENTAnnex 3. Costs of electricity from biomass
VIEW THE DOCUMENTAnnex 4. Land requirements for power stations
VIEW THE DOCUMENTAnnex 5. The Luz experience
VIEW THE DOCUMENTAnnex 6. Calculated cost of electricity from solar-thermal technologies
VIEW THE DOCUMENTAnnex 7. The photovoltaic effect
VIEW THE DOCUMENTAnnex 8. Cost of electricity from photovoltaic systems
VIEW THE DOCUMENTAnnex 9. Photovoltaic efficiencies
VIEW THE DOCUMENTAnnex 10. Photovoltaic module costs

Renewable Energy Technologies: A Review of the Status and Costs of Selected Technologies (WB, 1994, 184 p.)


Annex 1. Cost calculations and currency adjustments

The costs quoted in this paper are drawn from a variety of sources. Some are actual costs, whereas others are results of tabletop and engineering studies. Frequently, the sources quoted do not specify the details of their calculations and the assumptions made therein, such as discount rates and tax credits. Where these assumptions have been specified, I have attempted to note them. However, it is worth bearing in mind that this does cause difficulties in making direct cost comparisons.

Where data is available, the levelized cost of electricity has been calculated using the following standard formula

Cost of electricity (levelized) = (in $/kWh)


AC = Annualized capital cost (&/yr)
C = Total capital cost ($)

A = The annuity rate = ,

where r = 0.10, i.e., a discount rate of 10%, and n = life of plant (yr)
(O&M) = Annual operating and maintenance cost ($/yr)
F = Annual fuel cost for plant ($/yr.)
E = Number of kilowatt hours produced annually (kWh/yr).

All currency values have been converted to 1990 currency figures using the Consumer Price Index (line 64) quoted in the IMFs International Financial Statistics. They have then been converted to U.S. dollars (1990) using the period average of the market exchange rate (rf) taken from the same document. For 1992 dollars, an average of the first three quarters of the market exchange rate (rf) has been used for conversion to 1990 dollars. Any variations from the methods given above are noted in the relevant section of the text.

The reader is referred to the International Energy Agency's Guidelines for the Economic Analysis of Renewable Energy Technology Applications or to the Electric Power Research Institute's Technical Assessment Guide (EPRI TAG) for more detailed cost analyses of these technologies.

Annex 2. Costs of ethanol production

Table A2.1. Costs of Ethanol Production

Table A2.1. Costs of Ethanol Production (continued on next page)

Table A2.1. Costs of Ethanol Production (continued on next page)

Table A2.1. Costs of Ethanol Production (continued on next page)

Table A2.1. Costs of Ethanol Production (continued on next page)

Table A2.1. Costs of Ethanol Production (continued on next page)

Table A2.1. Costs of Ethanol Production (continued on next page)

Annex 3. Costs of electricity from biomass

Table A3.1. Costs of Electricity from Biomass (continued on next page)

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Annex 4. Land requirements for power stations

Table A 4.1. Land Requirements for Power Stations

(Table A4.1 continued)

Annex 5. The Luz experience

The bankruptcy of LUZ International Limited (Luz), the company responsible for setting up and running the Luz SEGS power plants in California, has raised many questions about the future of the technology. It should be noted, however, that the plants are still operating under new companies formed by groups of the SEGS plants' owners/investos (which include some U.S. utilities), and they continue to provide much information on technical performance and costs. A synopsis of the difficulties encountered by the Luz Corporation, along with comments, is presented below (see Lotker 1991, De Laquil and others 1993, and Kearney and Price 1992 for further information).

Each SEGS project was set up with private financing from investors, who benefited by receiving a return on their investment from revenues generated from electricity production; investors also benefited from certain financial incentives, such as Californian and U. S. Federal tax credits, that were in place at the time. The internal rate of return to investors was about 15 percent.

In 1991, Luz was unable to finance a tenth plant (SEGS X) because of financial and regulatory constraints. In the same year, the company was forced into bankruptcy. This business failure had a number of causes:

  1. The revenues generated from the sale of electricity were expected to cover the cash flow requirements of the plants, including operating and maintenance expenses. However, this sale price was linked to the price of natural gas, which progressively decreased from 1981 to 1991 (see figure), in real terms, by 78 percent This resulted in reduced electricity revenues.

b. Financial incentives, such as Californian and U.S. federal tax credits, although still available, had decreased by about half over the period 1981-91 (see figure) The incentives could also change unpredictably. For example, tax credits were renewed annually; however, in 1989 these were only renewed for nine months, forcing Luz to reduce the construction period for the SEGS IX plant from a planned ten months to seven months. This was achieved, but it weakened the company financially, as investors demanded a higher rate of return on their investments because of the increased risk, while vendors of goods and services charged a higher risk premium for their services from the company. Ironically, the tax credits were later extended in late 1990 until December 1991.

c. The state of California recognized the greater land requirement of these solar plants compared with, say, a natural gas plant, and therefore exempted the solar field part of the plant from a state property tax. This exemption expired at the end of 1990 and was not reenacted until May 15, 1991; the delay meant that the tenth SEGS plant was also required to be constructed in about seven months (to get in under the December 31, 1991, expiration of the energy credits). Hence, Luz was further "squeezed"' after the shortened construction period of the SEGS IX plant.

A number of important lessons can be learned from the Luz experience. First, consistency and durability of policies is essential. It is a prerequisite at the early stage of any new technology—particularly one that is highly capital-intensive. The unpredictable changes in this particular case not only squeezed Luz financially by causing it to accelerate construction of the SEGS IX plant from 10 to 7 months but also raised risks and deterred investors. Second, the wisdom of basing the price of electricity from a renewable energy technology on a mature fossil fuel price, such as natural gas, which is linked to other factors, must surely be questioned. Thus, not only were the positive environmental features of the technology not recognized in the price obtained for the electricity, generated but investors were deterred, because any investment was tantamount to "gambling" on future fossil fuel prices.

Figure A5.1. Energy Prices and Policy Support for Solar Energy, 1980-1991

Annex 6. Calculated cost of electricity from solar-thermal technologies

Table A6.1. Calculated Cost of Electricity from Solar-Thermal Technologies (continued on next page)

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Annex 7. The photovoltaic effect

Excellent descriptions of the photovoltaic effect may be found in the U.S. Department of Energy's Photovoltaic Fundamentals (U.S. DOE 1991), Kelly (1993), and other texts. This description is for the reader's convenience (diagrams are from U.S. DOE 1991}.

· A silicon atom has 14 electrons with 4 electrons in its outermost orbit.
· These 4 valence electrons are shared by 4 other silicon atoms in a crystal.
· So silicon atoms form a lattice.

A silicon atom

· Light of a specific energy can dislodge a negative electron from a bond, creating a positive hole.

· These negative and positive charges, which can move around freely, are the constituents of electricity.

Negative and positive charges

· Silicon can be droped with atoms of other elements to after the crystal’s electrical properties.
· n-type material (e.g., phosphorus atom with 5 valence electrons) is "dopant."

- Results in the presence of an extra unbonded electron in crystal.
- Electrons are the majority charge carriers.

N-type material

· p-type material (e.g., boron atom with 3 valence electrons) is "dopant."

- Results in a hole in the crystal.
- Holes are the majority charge carriers.

P-type material

· When a p-type material is placed In contact with an e-type rnaterial, an electric field forms at the junction.
· This Is caused by two effects:

a. Diffusion of the charge carriers from areas of high concentration to areas of low concentration.

b. Electric attraction by the opposite charge of the majority canters across the junction.

Diffusion of the charge carriers

· Eventually equilibrium is reached when any additional crossover is repelled.
· The strength of the field depends on the amount of dopant in the silicon.

The amount of dopant in the silicon.

When sunlight of a specific energy (called the "band gap.”) strikes the cell, charge carriers are created.

· These carriers would normally recombine in a fraction of a second, however the cell is so designed that the electric field across the junction pushes electrons to one side and holes to the other.

"Band gap.”

· If an external circuit is connected, current flows.
· Electrons from the n-layer can flow through the circuit to the p-layer and recombine with the holes.

If an external circuit is connected, current flows.

Annex 8. Cost of electricity from photovoltaic systems

Table A8.1. Cost of Electricity from Photovoltaic Systems (continued on next page)

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Annex 9. Photovoltaic efficiencies

Table A9.1. Photovoltaic Efficiencies (continued on next page)

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(Table A9.1 continued)

Annex 10. Photovoltaic module costs

Table A10.1. Photovoltaic Module Costs (continued on next page)

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Van Diemien Editions Techniq
Ch. da Lacuez 41
CH1807 Bionay
Tel: (021) 943 2873
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Oxford University Press
Maktaba Street
PO Box 5239
Dar es Salaam
Tel: (51) 29209
Fax (51) 46822

Central Books Distribution
306 Silon Road
Tel: (2) 235 5400
Fax: (2) 237-6321

Systematics Studies Unit
#9 Watts Street
Trinidad, West Indies
Tel: 809-662-5654
Fax: 803-662-5654

Gustro Ltd.
Medhveni Building
PO Box 9997
Plot 16/4 Jinja Rd.
Tel/Fax: (41 ) 254763

Microinfo Ltd.
P.O. Box 3
Alton Hampshire GU34 2PG
Tel: (1420) 86848
Fax: (1420)89889

University Bookshop
Gneat East Road Campus
P O. Box 32379
Tel: (1) 213221 Ext. 482

Longman Zimbabwe
Toude Road, Andbennie
PO. Box ST125
Tel: (4) 6216617
Fax: (4) 621670

The World Bank

1818 H Street, N.W.
Washington, D.C. 20433, U.S.A.

Telephone: (202) 477-1234
Facsimile: (202) 477-6391
Telex wui 64145 WORLDBANK
RCA 248423 WORLD8K
Cable Address: INTBAFRAD

European Office
66, avenue d'lna
75116 Paris, France
Telephone: (1)
Facsimile: (1)
Telex: 640651

Tokyo Office
Kokusai Building
1-1 Marunouchi 3 chome
Chiyoda-ku, Tokyo 100, Japan
Telephone: (3) 3214-5001
Facsimile: (3) 3214-3657
Telex: 26838

Cover photographs by Kulsum Ahmed and Said R. Mikhail
ISBN 0-8213-2744 5