Session 7

Question 1

How can the German climate/energy goals be reached?

Answer 1

• electrification of heating & transport
• decarbonization of power sector

Question 2

What is Power to Gas, how does it work?

Answer 2

• use power to transform H₂O into H and use it either directly or transform into synthetic natural gas (SNG)
• both can be used as energy source and be stored/transported with the existing gas infrastructure
• advantages
  
  • can be used to electrify heating & transport
  • both can help create effective energy storages
  • can help to absorb surplus production from renewable energy
• use directly as gases for heating & transport has 75-80% efficiency, storage and then use to generate power only 30-45%
• large storage capacity available
• could help to make hydrogen production carbon neutral (if done through renewables)

Question 3

How can transport/mobility be decarbonized?

Answer 3

• less mobility
• less energy intensive mobility (less individual car & air travel)
• less polluting tech
• many options for passenger cars, fewer for trucks, ships and air travel

Question 4

What characterizes Battery Electric Vehicles?

Answer 4

• actually more efficient per kWh than combustion
• advantages:
  
  • conversion of electric to mechanic energy highly efficient
  • easier to construct
• challenges:
  
  • batteries expensive & limited in capacities
  • charging slow
  • public grid not yet there
  • batteries are heavy
  • batteries have limited lifetime
  • charging of BEVs has to be coordinated to ensure grid stability
• characteristics
  
  • well suited for stop and go, not optimal for long distance travel at high speeds
• market share and stock are rising

Question 5

What characterizes Fuel Cell Vehicles (FCEV)?

Answer 5

• contain fuel cell that transforms H into electricity and charges small battery
• advantages
  
  • higher ranges than BEVs
  • refilling is fast
• disadvantages
  
  • less efficient than BEV in conversion of energy into mechanical energy
  • handling H difficult
  • no network for filling stations & no cars available currently

Question 6

How can heating be decarbonized?

Answer 6

• increasing efficiency
• switching to SNG as heat source
• geothermal heating (limited potential in DE)
• small scale: heat pumps
  
  • installations as in refrigerators and air conditioning
  • efficiencies of above 1 are possible
• solar heat: limited capacity
• biomass: limited capacity
• direct use of power in boilers

Question 7

How will future electricity demand change in Germany taking into account the climate goals?

Answer 7

even in best case scenario 600% increase in production from renewable source of electricity is necessary to guarantee autarky

Question 8

What potential has Germany in renewable energy sources?

Answer 8

• wind power and PV currently promise largest potential for expansion
• potentials
  
  • onshore wind: 930 GW, 2400 TWh/a
  • offshore wind: 70-80 GW, 280-300 TWh/a
  • PV: 180 - 450 GWp, 163-405 TWh/a
• but: only PV and wind cannot effectively match demand and supply as it is unsteady, phasing out dispatchable generation will be a challenge for grid stability
• flexibility:
  
  • grid expansion for more imports/exports
  • storage
  • build up renewable flexible generation
  • switch off overproduction
  • demand response: identify and make use of loads that are switchable