https://theconversation.com/how-to-have-an-all-renewable-electric-grid-120713
[images and links in online article]
How to have an all-renewable electric grid
August 22, 2019 8.36am EDT
David Timmons
Associate Professor of Economics, University of Massachusetts Boston
The main solution to climate change is well known – stop burning fossil
fuels. How to do this is more complicated, but as a scholar who does
energy modeling, I and others see the outlines of a post-fossil-fuel
future: We make electricity with renewable sources and electrify almost
everything.
That means running vehicles and trains on electricity, heating buildings
with electric heat pumps, electrifying industrial applications such as
steel production and using renewable electricity to make hydrogen
(similar to natural gas) for other requirements. So the focus is on
powering the electric grid with renewable sources.
There is debate, though, about whether fully renewable electricity
systems are feasible and how quickly the transition can be made. Here I
argue that feasibility is clear, so only the transition question is
relevant.
Known technologies
My research focuses on the economics of renewable energy. To demonstrate
feasibility and estimate cost of renewable electricity systems,
researchers use computer models that calculate potential production from
different technologies at each point in time, based on changing weather
conditions. A model reveals which combination of electricity sources and
energy storage systems has the lowest cost while always meeting demand.
Many studies demonstrate that fully renewable electric grids are
feasible in the United States, Europe, Australia and elsewhere. My
colleagues and I recently completed a small-scale study on the
island-nation of Mauritius. Islands are attractive places for initial
renewable transitions because of their small scale, relative simplicity
and dependence on imported fuels.
There are a number of ways to make renewable electricity: hydro, wind,
solar photovoltaics, geothermal and burning various forms of biomass
(plant matter), besides improving efficiency to use less energy. These
are mature technologies with known costs.
Other possibilities include wave, tidal and concentrating solar power,
where reflectors focus solar rays to produce power. While these may be
used in the future, the need to address climate change is urgent, and in
my estimation, the mature technologies suffice.
Opinions on nuclear energy run strong, which is another conversation.
But models show that the United States does not need nuclear energy to
retire fossil fuels.
The grid of the future
Renewable energy systems are location-specific: The best system depends
on a location’s resources (is it windy?), its temporal pattern (how
often is it not windy?) and availability of complementary sources (is
there hydropower for backup?). Despite this location sensitivity,
studies in disparate places are finding similar results.
Having a diversity of renewable sources can reduce costs. In particular,
solar and wind are complementary if the sunny season is not the windy
season; models find that a combination of both is typically less
expensive than either alone.
For most technologies, larger scale reduces cost. For example, in the
United States, large-scale solar farms can be more than 1,000 times
larger than residential rooftop systems and about half the cost. To
minimize cost, we build large systems.
Because solar and wind conditions vary across the landscape, system
costs fall as a production area grows, so there needs to be a robust
electric grid to move electricity from places where there is supply to
places of demand. We also need more electricity for applications like
transportation that currently use fossil fuels. This means the grid must
grow.
Studies show that running an electric grid with variable renewable
energy will include not using, or dumping, some energy at times, a
strategy that reduces cost compared to always storing surplus energy.
Still, some form of electricity storage is needed. Batteries work well
for smoothing short-term fluctuations, but for storing energy for many
hours or days, pumped hydroelectric storage is less expensive. Pumped
hydro uses any extra energy in the grid to pump water uphill, and when
energy is needed, the water runs back down to generate power in a
turbine. The United States has some existing examples and many feasible
locations. With grid expansion, storage may be located at a distance
from users.
Hydroelectricity and biomass power are available on demand, so having
these in a renewable electric grid shrinks the energy storage need and
reduces cost. Both have environmental effects that must be managed.
Hydropower can alter local ecosystems. Burning biomass emits carbon
dioxide, but a study I worked on shows that biomass emissions are
reversible and are clearly carbon-preferable to fossil-fuel emissions.
Sustainability also depends critically on management of biomass fields
and forests; the human track record on this has not been stellar.
Renewable energy systems require land. A U.S. study shows that supplying
all electricity from wind, water and solar would need 0.42% of land
area, plus 1.6% of land area for space between wind turbines. Biomass
energy requires much more land than wind or solar, so biomass must be a
small part of the renewable energy solution.
Real barriers are political and cultural
A future renewable electricity grid with associated electrification may
or may not reduce energy costs. But avoiding the worst effects of
climate change means quitting fossil fuels, whether or not this saves
money. Still, the renewable transition will be faster and politically
easier if it is less expensive.
In Mauritius, our study finds renewable electricity costs to be similar
to present costs there, based on current capital costs for renewable
energy. Some studies also find costs for future renewable electricity to
be lower than present fossil-fuel costs, in the likely event that costs
fall as we build more renewable energy systems and get better at doing it.
And that’s it, from a technical perspective. A combination of renewable
sources and energy storage – the specific combination depending on local
conditions and preferences – can supply all the electricity needed at an
affordable price, and will reduce air pollution to boot.
But government policies are needed to make a transition to renewable
energy. Climate change is an external cost – borne by society rather
than by energy producers – so market forces alone will not make the
transition. Besides putting a price on carbon (perhaps with dividends
returned to the public), government could make it easier to build the
needed infrastructure. And public support is needed: For example, public
acceptance of transmission lines to move electricity from the windy
Great Plains to city centers is another challenge for an all-renewable grid.
A project on the scale of transforming the energy system will create
jobs – many jobs – which is perhaps the economic measure of most
importance to the citizenry.
Research from me and others shows that fully renewable electric grids
are feasible with current technology at current prices; barriers to
using renewable electricity are more political and cultural than
technological or economic.
=====================================
To subscribe, unsubscribe, turn vacation mode on or off,
or carry out other user-actions for this list, visit
https://www.freelists.org/list/keiths-list
Note: new climate change website is now in pre-launch
Visit https://www.10n10.ca/e/index.shtml