The German Energiewende Electricity Solely From Renewable Resources
The German "Energiewende" Electricity Solely From Renewable Resources?
Contents § Introduction § Boundary conditions and presumptions § Simulation § Results § Conclusions
Introduction § CO 2 causes Greenhouse effect § Germany is one of the biggest CO 2 emittents § Countermeasure: „Energiewende“
Annual energy consumtion in Germany § 1202 TWh for heating § 718 TWh for fuels § 600 TWh electrical energy Heating Fuels Electricity
Present sources for electrical energy § Total average power: 70. 0 GW § Total energy: 600 TWh Others 5% Renewables 26% Electrical energy Black coal 18% Brown coal 26% Nuclear energy 16% Petroleum gas 10%
Renewable electrical energy § Annual total energy: 157. 4 TWh 60 48. 9 50 TWh 40 52. 4 35. 2 30 20. 8 20 10 0 Water Photovoltaics Bio mass Wind
Boundary conditions and presumptions § Presumptions: § Continuously increasing share of renewable energy § Chemical energy storage by H 2 via electrolysis Electrolyser H 2 tank Gas turbine 2 H 2 O -> O 2 + 2 H 2, Dh = +571, 8 k. J/mol
Boundary conditions and presumptions § Leading questions: § Optimum layout of photovoltaics, wind and (bio mass + water power)? § Required peak powers? § Maximum energy storage? § Required power for electrolysers and gas turbines?
Boundary conditions and presumptions § Realistic electricity consumption profile § Power: 32 – 94 GW § Total annual energy: 600 TWh Summer Power Maximum load Winter Maximum load Average load Basic load Time
Characteristics of renewables § Water Capacity fully used § Bio mass Ethical problems, only waste should be used § Geothermal energy Small scale § Wind Public resistance § Photovoltaics Expensive, small efficiency
Assumptions for weather § Annual number of depressions: 20 (period: 18 ¼ days) § Amplitude sun power: 15 – 100 % § Amplitude wind power: 0 – 100 % § Seasonal distribution of wind power: Between 5 % in June and 12 % in December § Phase shift between maximum sunlight and maximum wind: p/2 = 4 ½ days § Day length: 7 – 17 hrs
Simulation with Excel § 1 hr per line = 8760 lines for one year § Cosinus interpolation between the curves
Simulation of sun power § Present sunpower: § Heigth of sun over horizon (0 during nighttime) § Multiplied with weather factor
Simulation of wind power § Present wind power: § Weather factor § Multiplied by seasonal wind factor
Overlay of simulation results § Required power § Minus present sun power § Minus present wind power § Minus permanent power Water + Bio mass = 22. 8 GW § Equals § Electrolyser power (when negative) § Auxiliary gas power (when positive)
Optimum shares: § Solar 15 % § Wind > 50 % Power [GW] or Energy [TWh] Result 300 250 200 150 100 50 0 0% 10% 20% 30% 40% 50% 60% Share of photovoltaics Excess power [GW] Auxiliary power [GW] Required reservoir [TWh] 70%
Required powers § Required reservoir space: 26. 5 TWh § Required power: Source Peak power Existing Utilisation ratio [GW] (2013) Photovoltaics 75. 6 36. 0 13. 6% Wind 96. 7 33. 7 36. 6% Others 22. 8 100. 0% Electrolyser 53. 5 0. 0 23. 2% Gas standby 70. 6 21. 0 17. 6%
Conclusions § Enough electrical power can be produced by renewable energy § Storage space already exists § Technical bottleneck for the Energiewende: The realisation of high-power electrolysis § Economical bottleneck for the Energiewende: The recovery of the stored energy by gas power (average load less than 18 %)
- Slides: 18