Introduction - Wind Power Integration: Connection and System Operational Aspects - page 2

1.2 World energy and climate change

World primary energy demand more than doubled between 1971 and 2010 and is
expected to increase by another 40% by 2020. During the last 30 years there has
been a significant shift away from oil and towards natural gas. The latter accounted
for 21% of primary energy and 22% of electricity generation, worldwide, in 2010
(International Energy Agency, 2013).
When used for heating or electricity, natural gas generates lower carbon
dioxide emissions than coal or oil, and so the rise in carbon dioxide emissions
during the last 40 years did not match the growth in energy demand, and did not
quite double. However, increasing concerns over global warming have led world
governments to discuss ways of slowing down the increase in carbon dioxide
emissions. International climate change negotiations are proceeding under the
auspices of the United Nations, and, at a key meeting at Kyoto in December 1997,
an overall target for global reduction of greenhouse gases by 5% was agreed
between 1990 and the target date window of 2008-2012. National targets were then
set. The Kyoto protocol finally became legally binding on 16 February 2004. The
protocol was extended in December 2012 to include emission targets for the period
up to 2020, but still does not include the United States and China and only includes
about 15% of world carbon emissions.

1.2.1 Renewable energy
In 2010, renewable energy contributed 12.2% of world total primary energy
(2.3% hydro, 10% combustible renewables and waste, and 0.9% geothermal, solar
and wind). As much of the combustible renewables are used for heat, the
contributions for electricity generation were somewhat different: hydro contributed
16% and geothermal, solar, wind and combustible renewables contributed 3.7%.
Although significant amounts of hydro capacity are being constructed in the
developing world, most renewable energy activity in the developed world
is centred on wind, solar and biomass technologies. In 2010, world electricity
production from hydro accounted for 3,428 TWh and all other renewables

delivered 792 TWh (International Energy Agency, 2012).
There are no technical or economic reasons constraining the further develop-
ment of hydroelectric energy, but large-scale developments need substantial areas of
land for reservoirs and such sites tend to be difficult to identify. For this reason,
large-scale hydro generally does not come under the umbrella of most renewable
energy support mechanisms. Small-scale developments, including run of river
schemes, are generally supported, but these tend to have higher generation costs.
Future developments of tidal barrage schemes are likely to be constrained for similar
reasons, although the technology is well understood and proven. Tidal stream tech-
nology, on the other hand, is relatively new. It involves harnessing tidal currents
using underwater turbines that are similar in concept to wind turbines. It is the focus
of considerable research activity within the European Union and prototype devices
are currently being tested. Wave energy is also at a similar stage of development,