Unfortunately, most of the time the actual amount of electricity produced is only a fraction of the installed capacity .
Worse, on “bad days” it can fall to nearly zero. In 2016 for example
there were 52 nights with essentially no wind blowing in the country. No
Sun, no wind. Even taking “better days” into account, the average
electricity output of wind and solar energy installations in Germany
amounts to only about 17% of the installed capacity.
The obvious lesson is: if you want a stable, secure
electricity supply, then you will need reserve, or backup sources of
electricity which can be activated on more or less short notice to fill
the gaps between electricity demand and the fluctuating output from wind
and solar sources.
The more wind and solar energy a nation decides to generate, the more
backup capacity it will require. On “bad days” these backup sources
must be able to supply up to 100% of the nation’s electricity demand. On
“good days” (or during “good hours”) the backup sources will be used
less, or even turned off, so that their capacity utilization will also
be poor. Not very good economics.
Much better would be to limit wind and solar to a relative minimum,
and rely instead upon controllable, non-fluctuating power sources
operating with a high capacity factor, to meet the nation’s base load
electricity requirements and to adjust total output in accordance with
varying demand. This corresponds to world-wide practice prior to the
recent huge buildup with renewable energy.
In theory the ideal backup for wind and solar energy would be
to store excess electricity produced when the Sun is shining and strong
winds are blowing, and inject it back into the grid when needed.
Unfortunately, electricity is a difficult and expensive commodity to
store.
By far the most efficient presently available solution for storing
excess electric power is to use it to pump water against gravity into a
reservoir. When electricity is needed again, it is produced by letting
water flow down again via a turbine generator. In this process about 25%
of the energy is lost.
Naturally, the costs of construction and operation of such pump
storage plants will add to the real costs of providing electricity.
Plus, these installations use up a large amount of land area.
Here, too, Germany provides an instructive example. A
2014 study by the Bavarian Ministry of Energy came to the conclusion
that pump storage plants were not an economically viable solution. Much
better would be to exploit already existing water reservoir resources in
Norway and Sweden, where the capacity of pump storage plants can be
greatly expanded and new ones built at much lower cost.
This “solution,” however, would require transporting large amounts of
electricity over long distances back and forth between Germany and
those countries – which in turn would require additional high-voltage
lines and cables that have not been built and that no one wants to pay
for.
Given the high costs and other obstacles to creating large
electricity storage systems, it is not surprising that Germany’s
electricity storage capacity amounts today to less than 2% of total
electricity output.
There has been much discussion and research concerning alternative
ways to store electricity. Theoretically one could be to use excess
power to produce hydrogen, store it somehow and then use fuel cells to
generate electricity back from the hydrogen. This would be vastly more
expensive than pump storage, however, and with much greater losses.
Overdose of renewables?
Today, in order to guarantee stable baseline power and fill the gaps left by its fluctuating wind and solar generators, Germany
is forced to rely on (1) CO2-spouting coal and natural gas power
plants; (2) its remaining handful of nuclear plants, which it plans to
shut down by 2022; and most notably (3) importing electricity from other European nations.
German Chancellor Angela Merkel (CDU) fetches a green folder from
her briefcase at the start of a government consultation round
concerning bill on renewable energy at the Chancellery in Berlin,
Germany, 31 May 2016. Photo: AFP / Maurizio Gambarini / dpa
Most of the imports come from France, where about 75% of electricity
is produced by nuclear plants, and from Sweden, where 40% is
nuclear-produced. On “bad days” Germany could hardly get along without a piece of this much-dreaded nuclear energy.
On “good days” Germany floods the rest of Europe with excess power
from its wind and solar installations, often at dumping or even negative
prices. In this way Germany has turned its huge amounts of wildly
fluctuating renewable power sources into a European-wide problem.
Even with the flourishing European electricity trade,
however, Germany is still far from being able to close down its coal and
gas power plants.
The German Energy Agency (DENA) published a long-term scenario for
electricity production in Germany, based on the assumption that
so-called renewable sources should account for 80% of total electricity
consumption by the year 2050.
Among other things DENA concluded that in order to insure a stable
electricity supply, Germany would still need to maintain 61 gigawatts of
conventional power plant capacity “in reserve” and for a remaining
portion of base-load production. Electricity storage systems would
provide only 9% of reserve capacity in 2050.
Despite – and to a large extent because of — the massive
expansion of renewables, conventional power capacity could only be
reduced by 14% up to 2030 and by a maximum of 37% by 2050.
Given the government’s commitment to shut down nuclear energy in
Germany, this would mean keeping a large reserve of CO2 -emitting,
fossil fuel-based generation capacity. At the same time the political
decision has been made to phase out the coal-power stations which up to
now have produced the largest part of Germany’s electricity.
That leaves essentially only petroleum (heating oil) and natural gas
as realistic fuels for backup power. Natural gas would take first place
because it generates about 50% less CO2 per kWh of electricity than coal
or petroleum-powered plants.
With this background one can appreciate the German
government’s concern to guarantee long-term supplies of natural gas at
stable prices. Hence also the government’s insistence on the North
Stream 2 project to build a system of offshore natural gas pipelines
from Russia to Germany.
The good news, so to speak, is that for most of the time the backup
plants would operate at only a fraction of their installed capacity,
with many even standing still on “good days.” That way they would
release much less CO2 to the atmosphere.
That’s nice for the environment, but not a very efficient way to
utilize equipment, infrastructure and manpower – and not very attractive
for investors. Also it’s still far from the green dream of a CO2-free
energy system.
Preserving the stability of Germany’s electricity grid while at the
same time integrating tens of thousands of fluctuating energy sources
distributed over the entire country has been a major technical
challenge. It has meant reorganizing much of the electricity
transmission and distribution system, which was designed and built to
operate in a completely different regime.
It means also the construction of thousands of kilometers of new
high-voltage lines, including four projected long-distance transmission
lines which are needed to move electricity from the windy north to the
industrial west and south of the country.
This again adds to the real
(systemic) costs of supplying the country with electricity.
There is no doubt that the attempted transition to renewable sources
as the foundation of Germany’s energy system – Angela Merkel’s famous
“Energiewende” – has already significantly reduced the country’s
economic efficiency. The constantly rising electricity prices, taxes and
levies only begin to reflect the true costs of the government’s policy.
There is also a debate concerning the future stability of the
electricity grid.
Merkel and others often argue that a successful
“Energiewende” would place Germany in a unique position to export
know-how and technology for the ongoing “green transformation” of the
world economy. Increased income from export of green technology
is supposed to compensate for the costs of the Energiewende. This
calculation assumes that the other countries will choose to follow the
radical German example in reorganizing their power sectors, which is
doubtful.
Meanwhile resistance has been growing inside Germany itself,
as local environmental groups and citizens’ initiatives mobilize to
block construction of wind turbines, transmission lines, pump power
stations and other renewable energy projects.
The environmentalist ideology is coming into contradiction with
itself. The unprecedented scale of destruction of the natural landscape
by 30 000 gigantic wind turbines has brought a growing realization, that
reliance on renewable energy is by no means friendly to the environment
– and not necessarily safe.
People don’t want to live near wind turbines,
because of unpleasant noise and possibly dangerous infrasound emissions,
disturbing optical effects, reports of fires, broken-off turbine blades
flying through the air, ice throws, etc. And the dead birds.
In Germany there is political pressure to increase the
legally-set minimum for the distance between wind turbines and houses to
1 or even 1.5 kilometers, which would drastically reduce the
availability of construction sites. Already, protests and law suits have
brought the construction of new wind turbines in Germany to a
near-standstill.
Solar energy has encountered much less resistance, no doubt to a
large extent because only a few large solar farms have been built in the
country. Most of the present capacity comes from roof-mounted solar
cells, especially on private houses, where they have become quite
popular.
The big problem is how to store the electricity, which is generated
only during daylight hours and fluctuates according to the cloud cover.
So far relatively few house owners have been willing to pay for
batteries and other storage devices. Instead, excess electricity is
taken up by the grid at a subsidized price.
Projects for pump storage stations, and for new transmission lines
have met with such intense resistance, that there is little chance of
fulfilling the original goals of the Energiewende.
The question is, whether it makes sense at all to depart from the
tried-and-proven model of a stable electricity system based on
continuously functioning sources, a large percentage operating in base
load mode.
If we want the system to be largely CO2-free, then the only available option is nuclear energy.
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