POWER March 2017 - 54

RENEWABLE ENERGY
A 100% Renewable Grid: Pipe
Dream or Holy Grail?
The boom in renewable energy, spurred by dramatically falling costs, has led
some experts and political figures to begin talking seriously about what
was once science fiction: A world powered entirely by renewable generation.
But is it truly feasible or economic? One series of studies suggests it
is-with some important caveats.
Thomas W. Overton, JD
I
n the first half of the 20th century, as
the world struggled to come to terms
with dramatic leaps in technology across
transportation, communication, and energy
production, one favorite activity of media organs
was speculating about what the world
would look like 50 or 100 years in the future.
Popular Mechanics magazine was a favorite
forum for such predictions, and in the February
1950 issue, Waldemar Kaempffert, then
science editor of The New York Times, took a
stab at describing what the cities of the 21st
century would look like.
Among some fairly eye-opening ideas (for
example, housewives of the 2000s throw everything
away-laundry included-instead
of cleaning because synthetic manufacturing
has become so cheap and efficient),
Kaempffert offers some predictions on energy
that, if inexact, are nevertheless awfully
prescient for 2017. " It is a crime to
burn raw coal and pollute air with smoke and
soot, " he writes, and " [p]ower plants are not
driven by atomic power as you might suppose. "
Why? It's too expensive: " Because of
the heavy investment that has to be made in
a uranium or thorium power plant, " he says,
attention would soon turn to solar energy.
" Atomic power proves its worth in Canada,
South America and the Far East, but in tropical
countries it cannot compete with solar
power. "
In 1950, the idea of powering an entire
country with solar energy was science fiction.
But in 2017, it's become-paired with
wind and other renewable generation-an
idea many experts and policymakers are talking
about as an entirely feasible goal. Municipalities
around the world have made 100%
renewables targets a matter of law, large
corporations like Google and Amazon have
declared intentions to source all their power
needs from renewables (Figure 1), and even a
few countries such as Denmark that currently
rely on fossil fuels for a substantial portion
54
of their power are targeting 100% renewable
generation in the next few decades. Most recently,
the COP21 Paris climate agreement
set a target of 100% renewables worldwide
by 2050.
A Question of Labels
But is it really possible, as a matter of economics
and engineering, to transition an
entire national grid from fossil fuels to renewables
in just a few decades? At the outset,
it needs to be recognized that multiple
national grids operating on 100% (or close
to it) renewable energy sources already exist.
But all of them are nations that benefit from
a combination of small populations and large
hydroelectric capacity: Iceland, Norway,
Costa Rica, Paraguay, and Uruguay (Figure
2). The south island of New Zealand also
gets virtually all of its electricity from hydropower.
The largest of these-Paraguay-has
a population smaller than New York City
or London, and far smaller than giant cities
like Shanghai or Delhi. Other nations and regions
with high renewable penetration, such
as Germany and Portugal, have at times of
low demand and high renewable output met
or nearly met all electricity demand with renewable
generation.
A few island grids have also gone 100%
renewable, though not always with complete
success. The Spanish island of El Hierro in
the Canaries announced with much fanfare in
2014 a scheme to generate all of its electricity
from wind turbines and a pumped hydroelectric
storage facility (see " A Spanish Island's
100% Wind-and-Water Power Solution " in
the August 2014 issue). In practice, however,
the project has struggled to meet expectations,
generally supplying only a fraction of
the island's demand.
Answering the titular question requires
agreeing on certain definitions. Nuclear is
generally considered low-carbon generation
but is not usually included in 100% rewww.powermag.com
1.
Going green. The Amazon Fowler
Ridge Wind Farm (a 2016 POWER Top Plant),
which came online last year, is part of the
company's long-term plan to source 100% of
its electricity needs from renewable energy.
Amazon has power-purchase agreements
with several other wind farms under development
or construction. Courtesy: Amazon
newable scenarios for a variety of reasons,
usually environmental but also including
proliferation concerns. Many countries, especially
in Europe, have grids that are deeply
interconnected with each other, and in these
cases nations with high renewable penetration
often rely on neighboring grids for balancing
purposes, much as a home with a
large solar array and no storage needs a grid
connection even if its net generation may be
zero. Denmark, for example, met 52% of its
demand with renewables in 2015, but it also
imported 20% of its electricity. Scenarios
like the latter are not fairly viewed as " 100%
renewable. "
Corporate and municipal pledges to source
POWER | March 2017
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POWER March 2017

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