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Geothermal energy generation: total potential at depths of 2000 to 5000 metres,
in megawatt-hours per square kilometre per year. It can supply heating and
process heat and power. Geothermal power generators are frequently operated
as base-load plants due to the large investment needed for their construction.
Biomass resource – sum of the energy potential, in terajoules per square
kilometre per year. Using biomass as a stored energy source, renewable
energy can be produced to compensate for fluctuations in solar and wind
power generation.
“During the first oil price crisis, the whole world suddenly start-
ed researching energy. Politicians ‘woke up’ and put money in-
to it. DLR – at that time still the German Research and Experi-
mental Institute for Aviation and Space (Deutsche Forschungs-
und Versuchsanstalt für Luft- und Raumfahrt; DFVLR) – had a
great deal of expertise to undertake such research projects,
both for developing various energy technologies and for theo-
retical systems analysis.” Commissioners of the initial studies
included German Federal Education and Research Minister
Hans Matthöfer, who had been interested in the potential of
developing renewable energies since 1977, and the State of
Baden-Württemberg, which commissioned a major study into
the prospects for energy supply in the 1980s. In these initial
studies, DLR researchers also investigated the potential of hy-
drogen in the energy system. “From the outset, our depart-
ment consisted of engineers and physicists. The advantage of
this was that our studies were always very close to the tech-
nologies, and we could estimate what was possible and what
was not with great accuracy,” recalls Nitsch. And today, with
economists, geographers and a social scientist in the team,
there are still regular exchanges with the engineers regarding
the possibilities of individual technologies, according to Nitsch.
“And there is also the occasional argument when we view the
situation differently. This close feedback with the researchers is
what makes systems analysis at DLR unique.”
Other milestones for systems analysis in Stuttgart are the
main studies into possible development strategies for renewa-
ble energy sources in Germany, which DLR has been producing
for the Federal Environment Agency since 1998 and for the
Federal Environment Ministry (BMU) since 2004. DLR research-
ers were able to build on the foundation studies on ‘Energy
Supply for the Future’ carried out in 1990. This was followed
by international studies (again done under contract to the
BMU) such as Trans-CSP (Trans-Mediterranean interconnection
for Concentrating Solar Power) and MED-CSP (Concentrating
Solar Power for the Mediterranean Region), which looked into
developing an electricity network between Europe, the Middle
East and North Africa. The DESERTEC Foundation and the DE-
SERTEC Industrial Initiative continued these studies. This is be-
cause they have set themselves the goal of delivering such an
energy network. “DLR has been establishing an ever broader
foundation for studies into energy systems since the early
1970s. The modelling has reached a peak with the REMix tool;
gas emissions by 2050. But to do this they assume there will
be various developments in, for example, electric mobility. In
addition, the researchers have computed the development
path for reducing greenhouse gases by 95 percent. “Using the
various scenarios, we get a range of potential developments
and understand how important individual technologies are for
the Energy Transition,” says Pregger, describing the benefits of
this process.
Energy modelling – an unbiased look into the future
Unlike scenario computations that assume specific tar-
gets, optimisation modelling leaves the results that will be ar-
rived at open. With the REMix (Renewable Energy Mix for Sus-
tainable Electricity Supply) modelling programme, the systems
analysts can reliably draw up minimum-cost energy supply sys-
tems that are economically viable under the respective cost as-
sumptions. The computations for this are complicated, as RE-
Mix compares the power demand and the potential energy
supply for individual countries or for the whole of Europe for
every hour over the course of a year. In the case of a large re-
gion or a high temporal resolution, these calculations can
sometimes take several days. With the REMix modelling tool,
the systems analysts are currently focusing their research on
whether and how realistic the scenarios they have computed
are. For each year of the scenario, they can check the extent to
which the complex of power plants computed in the scenario
can meet the energy demand and how many storage units are
required. “We can make sounder predictions in our scenarios
with the optimisation models,” says Yvonne Scholz, who de-
veloped REMix for her doctorate. She also knows the limita-
tions: “The quality and usability of the results depends largely
on the parameters and basic assumptions entered. We have to
carry out our computations with numerous parameter varia-
tions to get sound predictions.” This means that, even with
the optimisation models, numerous iterations are needed on
the way to a realistic model of the energy requirement for the
future.
How did DLR end up performing energy systems analysis?
How did the German Aerospace Center end up comput-
ing scenarios for future energy supply? If anyone knows, it’s
Joachim Nitsch, who established the department in 1975:
furthermore, we can now map the heat sector very well and
analyse the resources for renewable energy sources both glob-
ally and domestically,” says Joachim Nitsch in praise of his for-
mer department.
The systems analysts have not developed any preference
for a specific technology yet: “Future energy supply will be a
combination of various technologies, depending on the poten-
tial available in a country,” says Pregger, adding: “Scenarios
are not just standard off-the-shelf tools. We have our experi-
ence to draw on, and if a client’s requirement does not follow
a consistent development path in our eyes, it will be dis-
cussed.” This was the case with the Greenpeace scenario,
where the researchers could not feed in all the basic condi-
tions with the client’s exact specifications. This meant that they
could not adhere to the strict path for gas consumption,
which assumed that no new reserves would be tapped. “To
manage the transition to a renewable supply while at the
same time making the least possible use of biomass, gas will
have to continue to play an important role as a source of ener-
gy in the long term,” notes Pregger. With the addition of new
gas reserves, the DLR researchers were able to use various sce-
narios to illustrate a coherent development path, at the end of
which more than 80 percent of primary energy will still come
from sustainable sources in 2050, even as the global popula-
tion continues to increase at a steady pace.
Our energy supply is changing; the expansion of renew-
able energy sources is progressing and, at the same time, re-
serves of oil, gas and coal are becoming limited. With the En-
ergy Transition, politicians have decided that Germany will rely
on renewable forms of energy in the long term. Nobody can
look into the future of energy supply, but energy scenarios like
those being generated by the DLR systems analysts provide im-
portant bases for decision-making by politicians and econo-
mists.
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Solar energy resource – total horizontal irradiance, in kilowatt-hours per square
metre per year. Total irradiance is the sum of direct and diffuse irradiance. In
desert regions, this is more than twice than in central Europe.
How can an energy network between North Africa and Europe be established?
What is the best energy mix for this? The DLR systems analysts have
researched this for the first time. These studies form the basis for the
DESERTEC concept, which the DESERTEC Foundation and the DESERTEC
Industrial Initiative are working on today.
Since 2004, the DLR researchers have been working on studies for the German Federal Ministry for the Environment, Nature Conservation and
Nuclear Safety (BMU), to see what the energy supply in Germany might look like in the future. The scenario illustrated here shows the develop-
ment with an average speed of growth in renewable energies until they reach 85 percent of power generation.
Development of gross energy generation in Germany according to the 2011 Scenario A
(average expansion of renewable energies; use of biofuels, electric mobility and hydrogen in transport).
614
2005
2010
2015
2020
2025
2030
2040
2050
700
600
500
400
300
200
100
0
617
Hydrogen renewable energy (CHP, gas turbine)
European renewable energy network
Photovoltaic
Wind energy
Geothermal energy
Hydroelectricity
Biomass
CHP, gas, coal
Gas, oil
Lignite
Coal
Nuclear energy
585
564
558
548
562
574
Bruttostromerzeugung, [TWh/a]
G oss electricity production [TWh/a]
More information:
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