Monday, September 8, 2014

Running entirely on Renewable Energy-Germany in 2050

A research project funded by Germany’s Federal Ministry for the Environment shows that if renewable energy sources were networked with storage systems and standby power plant, they could secure the country’s power supply in the future. How much that would cost is another story.
A research project funded by Germany’s Federal Ministry for the Environment shows that if renewable energy sources were networked with storage systems and standby power plant, they could secure the country’s power supply in the future. How much that would cost is another story.
February 1, 2050, is a good day for German electricity consumers. The breeze off the north coast is blowing so strongly that offshore wind farms and the wind turbines on land are running non-stop. Since it's a sunny day, photovoltaic modules, which are mostly located in the south, are also working at peak capacity. On monitors in a central control room, engineers can see from a diagram that, in total, an average of 80 gigawatts (GW) of renewable electricity is being generated, with a midday peak that is as high as 120 GW.
In this scenario, renewable electricity produces enough energy to supply industry, trade, commerce, and households throughout Germany with power derived exclusively from wind and sunlight. The largest consumers are Berlin, Hamburg, and the municipalities in the Ruhr district. But thanks to new transmission lines, densely populated areas such as these have no problem. If at some point there isn't enough wind or the sun isn't out, this scenario includes standby power plants that operate on methane and biogas systems — but they certainly aren't needed today. Staff members in the control room decide that this is an ideal day for replenishing storage systems across the country with excess electricity and using power-to-gas systems to produce methane gas that can be fed into the natural gas lines or turned into electricity again. Can an infrastructure based almost completely on renewable energy provide grid stability and dependability in the same way that fossil-fuel plants do today as demand rises and falls? In other words, are technical solutions up to the task of balancing natural fluctuations in the wind and the sun?
As a result, power-to-gas plants will play a crucial role. These plants would use excess renewable electricity to decompose water into its constituents (hydrogen and oxygen) in the chemical process known as electrolysis. Carbon dioxide (CO2) would then be added to produce methane gas. The methane would then power gas and steam turbine power plants directly — and be converted back into electricity with an efficiency rate of more than 60 percent. Methane can replace natural gas, and it can be fed into the public gas grid. The study pointed out that the German natural gas grid can easily handle the storage needs of renewable energy surpluses. Wind and solar power stations would be supplemented by biomass plants in addition to gas-fired power plants. Both can respond quickly and flexibly and can thus be used to balance out fluctuations in power generation. However, researchers have calculated that these power plants must be numerous enough to collectively be capable of reaching approximately the maximum load in Germany. Even if existing gas-fired power plants could be used for this purpose, this would still require the construction of plants capable of generating tens of additional gigawatts,which would be a problematic investment if the plants were needed only a few hundred hours per year.
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