According to a new study, 100 percent of the world's
energy needs can be met by renewable sources in 20-40 years
Here at Gizmag we cover a seemingly endless stream of
renewable energy technologies designed to wean us off our
reliance on fossil fuels and improve the health of the planet.
As important as such developments are, for these technologies to
have an impact they must of course be implemented – and on a
large scale. What has been sorely lacking is a plan to
accomplish such a Herculean feat. Now researchers from the
University of California-Davis and Stanford University have
published a study that details one scenario to completely
convert the world to clean, renewable energy sources – and they
say it could be done in 20 to 40 years using technology
available today at costs comparable to fossil fuel-based energy.
Electricity the key
The two part paper coauthored by
Stanford
researcher Mark Z. Jacobson and Mark Delucchi, of
UC-Davis, evaluates not only the technology required, but
also the costs and material requirements for converting the
planet to renewable energy sources. Their plan would see the
world running predominantly on electricity, with 90 percent of
this sourced from
wind and
solar.
The remainder would be made up from
geothermal and
hydroelectric sources, which would provide around four
percent each, while
wave and
tidal power would contribute the remaining two percent.
For our transport energy needs, cars, trucks, motorbikes,
ships and trains would be powered by
electricity and
hydrogen fuel cells, while aircraft would be fueled by
liquid hydrogen. Commercial processes would also be powered by
electricity and hydrogen, which would be produced using
electricity. Meanwhile, our homes would eschew natural gas and
coal in favor of electric heaters, while water would be
preheated by the sun.
20 to 40 years
"We wanted to quantify what is necessary in order to replace
all the current energy infrastructure – for all purposes – with
a really clean and sustainable energy infrastructure within 20
to 40 years," said Jacobson.
To that end, the plan would see all new energy generation
coming from wind, water and solar by 2030, and all pre-existing
energy production converted by 2050. The researchers say that
the millions of lives saved by the reduction in air pollution
and a 30 percent reduction in world energy demand – thanks to
the conversion of combustion processes to the more efficient
electrical and hydrogen fuel cell processes – would help keep
the cost of such a conversion down.
"When you actually account for all the costs to society –
including medical costs – of the current fuel structure, the
costs of our plan are relatively similar to what we have today,"
Jacobson said.
Addressing variability of solar and wind
To overcome that variability of wind and solar and ensure
there is a reliable base load of energy Jacobson says wind,
water and solar energy sources could be combined as a single
commodity as they are generally complimentary. Solar peaks
during the day, while wind generally peaks at night, and
hydroelectric could be used used to fill the gaps.
The plan also envisages the connection of geographically
diverse regions using long-distance transmission to overcome
energy shortfalls in a given area. If the wind or solar energy
generation conditions are poor in a particular area on a given
day, connecting widely dispersed sites would allow electricity
to be provided from a few hundred miles away where the sun is
shining or the wind blowing.
"With a system that is 100 percent wind, water and solar, you
can't use normal methods for matching supply and demand. You
have to have what people call a supergrid, with long-distance
transmission and really good management," said Delucci.
Additionally, off-peak electricity could be used to produce
hydrogen for the industrial and transportation sectors and, as
it is today, pricing could be used to control peak demands.
Material considerations
While the large-scale construction of wind and solar power
plants would require large amounts of materials, the researchers
found that even rare materials, such as platinum and the rare
earth metals, are available in sufficient amounts for their plan
to be realized. They say recycling could also be used to extend
the supply further.
"For solar cells there are different materials, but there are
so many choices that if one becomes short, you can switch,"
Jacobson said. "Major materials for wind energy are concrete and
steel and there is no shortage of those."
Crunching the numbers
The researchers also calculated how many wind turbines, solar
plants, rooftop photovoltaic cells, geothermal, hydroelectric,
tidal and wave-energy installations would be required to provide
100 percent of the world’s energy needs. They found that 0.4
percent of the world’s land would be needed – mostly dedicated
to solar – and that the spacing between installations – mostly
wind turbine spacing – would add another 0.6 percent, much of
which could be used for other purposes.
"Most of the land between wind turbines is available for
other uses, such as pasture or farming," Jacobson said. "The
actual footprint required by wind turbines to power half the
world's energy is less than the area of Manhattan."
Long way to go
Already 70 percent of the hydroelectric sources needed to
realize the plan are already in place, but only about one
percent of the wind turbines required and an even lesser
percentage of solar power. But the researchers say their plan is
doable.
"This really involves a large scale transformation. It would
require an effort comparable to the Apollo moon project or
constructing the interstate highway system," Jacobson says. “But
it is possible, without even having to go to new technologies.
We really need to just decide collectively that this is the
direction we want to head as a society."
Th researchers two part paper appears in the journal
Energy Policy.
Via
Stanford University News.
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