Visualizing Environmental Science

© Kyoungil Jeon/Getty; inset, © Fabio Bianchini/iStockphoto

0

0.2

0.4

0.6

0.8

1

1.2

1980

Cost per kilowatt-hour (dollars)

1985 1990 1995

Year

2000 2005 2010

Based on data from M. A. Schilling, M. Esmundo,

Energy

Policy

37 (2009) 1767–1781; U.S. DOE Energy Information

Agency, (2012).

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These thin-film solar cells look much like conventional roofing

materials.

'ENERATINGCOSTSOFELECTRICPOWERPLANTS sTable 18.1

Generating costs (cents

Energy source per kilowatt-hour)*

Hydropower 2–10

Biomass 6–9

Geothermal 3–8

Wind 4–7

Solar thermal 5–13

Photovoltaics 15–25

Natural gas 5–7

Coal 6–8

Nuclear power 6–8

*Electricity production and consumption are measured in

kilowatt-hours (kWh). As an example, one 50-watt light bulb

that is on for 20 hours uses 1 kWh of electricity (50 × 20 = 1000

watt-hours = 1 kWh).

Cost of electricity from solar photovoltaic
ViÃ]Ê£™näqÓä£äÊUʈ}ÕÀiÊ£n°ÎÊ

The cost of generating electricity using photovoltaic cells has
dropped from over one dollar per kilowatt-hour three decades
ago to about $0.15 in 2010.

The average cost of electricity

to consumers in the United States is currently

about 12 cents per kilowatt-hour. Based on this

graph, in what year do you expect power from

photovoltaics to cost less than the average cost?

Think Critically

manufacture than standard PVs, has decreased costs for

PVs across the board. Japan is considering a national policy

that all new buildings incorporate PV on rooftops by 2030.

Through the Million Solar Roofs initiative, California ex-

pects to have solar roofing on 1 million buildings by 2016.

By late 2012, Californians had installed over 1000 MW

of solar capacity on their roofs. This is equivalent to the

power generated by a typical nuclear power plant. An-

other technological advance that shows promise is dye-

sensitized solar cells, which can be produced at about

one-fifth the cost of conventional silicon panels.

While operating PVs creates no air or water pollution,

the manufacturing process requires industrial chemicals,

many of which are toxic. Finding cleaner ways to produce

solar panels will be important as more are produced.

Solar Thermal Electric

Generation

Systems that concentrate solar en-

ergy to heat fluids have long been

used for buildings and indus-

trial processes. In solar thermal

electric generation, electricity is

produced by systems that collect

solar thermal

electric

generation

A means of producing

electricity in which

the sun’s energy is

concentrated using

mirrors or lenses onto

a fluid-filled pipe; the

heated fluid is used to

generate electricity.

Direct Solar Energy 447