The Ecology Book

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turbines connected to generators.

China is the biggest producer of

hydroelectric power (HEP), with

45,000 small installations in addition

to “big-dam” schemes such as the

Three Gorges project, whose 32

giant turbines have the capacity

to produce 22,500 megawatts of

electricity. A downside of big HEP

schemes is that reservoirs created

upstream of the dam can flood

good farmland, forcing people to

relocate and destroying ecosystems.

Despite this, the IEA has estimated

that by 2023, hydropower will be

meeting 16 percent of the global

demand for electricity.

Tidal power is based on the

same principle: moving water turns

turbines, which drive electricity

generators. The source of energy

from a tidal scheme is reliable,

generating power each time the

tide ebbs and flows, but such

schemes are expensive to construct.

At present, the largest is the Sihwa

Lake Tidal Power Station in South

Korea, which was completed in

2011 and has reduced the annual

amount of CO 2 the nation generates

by 315,000 tons (286,000 tonnes).

Wave power involves the capture

of wave energy through a converter.

The first commercial wave power

scheme began off the west coast

of Scotland in 2000, and the first

multi-generator wave farm opened

at Aguçadoura in Portugal in 2008.

Biomass

Organic matter from plants or

animals is known as biomass.

It contains stored energy because

plants absorb the solar power they

need for growth via photosynthesis,

and creatures absorb that energy

either from the plants they eat

or from what their prey consumes.

Creating a renewable fuel from

plant, animal, and human waste

products such as straw, dung, and

garbage may seem an attractive

option, and some coal-fired power

stations have been converted to

wood-burners. Burning biomass

produces heat, electricity, and

transport fuels, such as ethanol and

biodiesel. However, biomass energy

is not necessarily “clean.” Burned

as a fuel, biomass releases CO 2 , and

creates air and particle pollution.

Clearing prime forest for its wood or

to cultivate biomass crops, such as

ENVIRONMENTALISM AND CONSERVATION

grain for biofuels, can also damage

the environment. Perhaps because

of this, biomass is a more common

fuel in nations that cannot afford

other renewable options. According

to the IEA, the majority of solid

biofuel supply in 2016 took place in

Africa, accounting for 33.2 percent.

The future

As growth in renewables increases,

the advantages of each type must

be balanced against their adverse

effects—from biomass pollution to

the reported role of wind turbine

blades in the deaths of migrating

birds. In 2014, the IEA predicted that

renewables would provide 40 percent

of global energy needs by 2040. In

2018, the IEA further predicted that

renewables would account for almost

a third of all world electricity by

2023, with solar power taking the

biggest share. Energy from ocean

currents could also generate huge

amounts of electricity, as could

large arrays of solar panels in space

or floating on the seas. ■

World energy supply by source in 2016

Renewables

13.7%

Coal

27.1%

Natural

gas

22.1%

Oil

31.9%

Hydro

2.5%

Biofuels

and

waste

9.5%

Other

renewables 1.7%

Nuclear

4.9%

Others

0.3%

A pie chart illustrating the sources for the total

energy produced and supplied throughout the world

in 2016, according to data published by the IEA.

“Others” includes nonrenewable wastes and other

sources not included elsewhere such as fuel cells.

... someday, renewable energy

will be the only way for people

to satisfy their energy needs.

Hermann Scheer

President, European Association

for Renewable Energy

US_300-305_Renewable_energy.indd 305 22/11/2018 17:51