AMSTERDAM — Scientists have developed a comprehensive computer model that simulates German energy supply and demand, in a bid to establish whether it is feasible for Germany to rely on renewable energy sources to power its economy and meet its carbon dioxide emission reduction targets.
Developed by Hans-Martin Henning and Andreas Palzer, two physicists at the Fraunhofer Institute for Solar Energy Systems, in Freiburg, the Renewable Energy Model-Deutschland, or REMod-D, is a computer simulation that models an all-sector future energy system for Germany, matching supply and demand on an hourly basis over a full year.
Using real data from 2011 and 2012, the researchers have run millions of simulations to optimize the model. They say they have demonstrated that there are several economically viable ways to achieve a low-carbon future, using existing technologies.
“We wanted to answer the question: Is it possible for Germany to meet its ambitious CO2 reduction target using predominantly renewable energies?” Mr. Henning said in an interview. “And, if yes, what is the composition of this system, and what is its cost?”
The answer to the first question is an unequivocal “yes,” according to Eicke Weber, the institute’s director and a professor of physics at Freiburg University.
“It is economically to our advantage to move as quickly as possible to a system of 80 percent renewable energy,” Professor Weber said during an interview.
“Our researchers have shown that the cost of this transformation of the entire energy system — not just electricity — would be the same as today’s system to run; but the needed investments would cost less than what would be saved by spending far less on fossil fuels,” Professor Weber said.
“Our estimate is that the changeover will cost about 500 billion euros,” or about $628 billion, he said. “However, between now and 2050 we will realize savings of between €600 billion and €1,000 billion. These are savings on the total energy system, including fossil fuels and the distribution system.”
“To go beyond 80 percent would cost a lot more,” he added. “But the low-hanging fruit is to start with an 80 percent renewable energy system. The faster you add renewable energy to the grid, the faster you reach the crossover point where the savings become greater than the costs. We estimate that Germany could reach that point as soon as 2025.”
The simulations show that switching to a low carbon economy can be done without damaging businesses or living standards, Mr. Henning said.
“We set as a baseline condition of our model that CO2 emissions could not exceed Germany’s ambitious CO2 reduction target for 2050,” he said. “Germany is committed to reducing its CO2 emissions by at least 80 percent below 1990 levels by then.”
“Another baseline condition was that Germany would not be economically harmed by our results,” Mr. Henning added. “Industry would become more efficient but would remain strong. There would be no decrease in the standard of living, in comfort levels or in mobility.”
“Everything is included in this model, starting from electricity generation, storage and end-use electricity, all the fuel sectors including biomass and also hydrogen production and even methane from power-to-gas technologies,” Mr. Henning said. “For mobility, electric vehicles, hydrogen-powered vehicles, and also fuel-powered vehicles are part of the model.”
“We think that this is probably the first model that is really able to appropriately treat this challenge of a highly complex system with many interdependencies and many components,” he said.
Prof. Manfred Fischedick, vice president at the Wuppertal Institute for Climate, Environment and Energy, said the model was an important contribution to discussions about renewable energy. “There are not many studies available trying to investigate what a renewable energy-based system would look like,” Professor Fischedick said. “This model distinguishes itself by its level of technological detail and its comprehensive coverage of the relevant interactions in the system.”
Energy efficiency in buildings is an important variable in the model — the more buildings are retrofitted to save on heat and power, the less solar and wind generating capacity needs to be installed. Another variable is the balance between renewable energies, conventional power plants and gas-fueled combined heat and power, or C.H.P., plants.
As an example of one scenario produced by the model, based on existing technologies and conservative projections of future cost trends for renewables, Mr. Henning cited an energy system incorporating a 40 percent reduction from current levels in building heating requirements.
Taking into account the baseline requirement for reduced carbon emissions — implying a large-scale closure of conventional thermal power plants and a switch away from gasoline and diesel-powered cars — “we would need 150 gigawatts of photovoltaics, about 120 gigawatts of onshore wind, about 30 gigawatts of offshore wind, and an electric capacity of 60 gigawatts of C.H.P. that would supply all the residual electricity needs of the system,” he said.
Germany currently has 35 gigawatts of installed photovoltaic generation and 30 gigawatts of onshore wind.
In this scenario, offshore wind capacity would be limited for environmental reasons, he said, while the electricity system would incorporate substantial storage capacity to handle the fluctuations of supply and demand. This could take the form of about eight million batteries connected to home photovoltaic systems and a doubling of current pumped storage capacity. Heat storage would be split among about 150 large-scale centralized storage plants and about seven million home storage units.
Finally, about 33 gigawatts of electrolytic plants would produce hydrogen or methane fuel for transportation.
“Altogether, this system uses 78 percent renewable energy,” Mr. Henning said, “and has a much higher overall efficiency than today’s system.”
Efficiency improvements would come from retrofitting insulation in buildings to cut heat loss; closing thermal power plants, “which produce lots of waste heat”; and switching a large part of the auto fleet to renewable energy, “either directly with batteries, or indirectly by using hydrogen or methane generated by renewable electricity,” he said.
Contrary to popular fears, Mr. Henning said, “there are many hours when renewables are not sufficient to meet demand, but even more hours when we have too much renewable energy.”
This system, after installation, would have running costs very close to the present system’s running costs of about 260 billion euros, or about $326 billion, per year, Mr. Henning and Mr. Palzer said.
According to their calculations, the cumulative investment over the next 35 years for all major renewable energy sources required by this system would amount to €470 billion. But this would save €660 billion in avoided fuel costs, at constant fossil fuel prices. If fossil fuel prices rose by 1 percent per year during this period, then the avoided fuel cost would be €830 billion. And if fossil fuel prices rose by 2 percent per year, the avoided cost would be €1,045 billion.
In addition, “our model would lead to significant local employment creation for the installation and running of the hundreds of thousands of components of all the conversion and end-use sectors,” Mr. Henning said.
Link to original article from the New York Times.