UE 13: Sector integration

Question 1

Name flexibility options for the integration of renewable energies.

Answer 1

Efficient grids

• Electricity grids: Grid optimization, reinforcement and expansion
• Coupling with gas grids and heat grids in the context of sector coupling
• Imports/exports

Flexible consumers/Demand side management

• Load management in industry, service sector and households (especially electric heat pumps and electric vehicles)
• Power-to-heat as a sector coupling technology

Storages

• Electricity storage
  –> Pumped storage
  –> Compressed air storage
  –> Battery storage/accumulators
• Heat & gas storage
  –> Power-to-gas/power-to-liquids as a sector coupling technology
  –> Expansion of heat storage/gas storage for flexibilization of CHP or power-to-heat

Flexible producers

• (Controllable) renewable energies
  –> Flexible use of biomass and biogas
  –> Grid- or market-induced curtailment of wind and photovoltaics
• Retro-fitted carbon neutral power plants
  –> Transition: Retro-fitted existing (gas fired) power plants, CCS
  –> Electricity-led use of CHP depending on electricity prices
  –> New construction of flexible (hydrogen-fired) power plants

Question 2

What is missing?

Flexibility Options for the Integration of Renewable Energies

• “…” in generation and consumption
• “…” in energy transport
• Goal: integration of renewable energies

Answer 2

“Temporal flexibility”

“Spatial flexibility”

Question 3

What is missing?

Flexibility options: grid expansion

• Goal: Overcoming “…”

Answer 3

“spatial discrepancies/providing spatial flexibility”

Question 4

What is missing?

Flexibility options: storages

• Goal: Overcoming “…”

Answer 4

“temporal discrepancy/providing temporal flexibility”

Question 5

Provide the actual technologies behind:

1) Power-to-Heat
2) Power-to-Mobility
3) Power-to-Gas
4) Power-to-Liquids
5) Hydrogen-to-Heat
6) Hydrogen-to-Mobility
7) Hydrogen-to-Electricity

Answer 5

1) Power-to-Heat

• Heat pump
• Electrode boiler

2) Power-to-Mobility

• Electric Motors and batteries

3) Power-to-Gas

• Electrolysis
• Pyrolysis

4) Power-to-Liquids

• PtG + Fischer–Tropsch process

5) Hydrogen-to-Heat

• H2 gas heater
• H2 CHP

6) Hydrogen-to-Mobility

• Electromobility fuel cell
• Synthetic fuels

7) Hydrogen-to-Electricity

• Fuel cell
• H2 gas turbine
• H2 CHP

Question 6

What are the advantages of sector coupling/integration?

Answer 6

Improved energy efficiency

• E.g. waste heat from industry can be used to heat buildings (e.g., district heating)
• E.g. using electricity directly in heating and transport (e.g., heat pumps, electric vehicles) increases the energy efficiency

Integration of renewables into energy system

• E.g. avoiding curtailment by using surplus power (through flexible consumers (e.g. PtG))

Increasing flexibility and grid stability

• E.g. flexible consumers curb/delay demand in times of a high residual load and increases demand in times of a negative residual load
• E.g. grid expansion enabling more options to balance supply and demand

Decarbonization of hard-to-abate sectors

• Green hydrogen or synthetic fuels made from renewable electricity can decarbonize sectors like steel, aviation, or shipping.

Question 7

True or false?

Power-to-Heat: Converting Power (Surpluses) into Heat and Replacing Fossil Fuels

• In principle, both space heat and process heat can be generated by power-to-heat.
• Space heating can be generated decentrally (at the customer) OR generated centrally and then distributed via district heating.
• There are several technologies available for process heat, but often processes must be adapted to switch from conventional to electric heating.
  –> Not all processes can be switched to electric heating (e.g. temperature level requirements, need for carbon).
  –> Adjustments to processes often lead to pauses in production and are therefore only possible when major revisions are due anyway.

Answer 7

True!

Question 8

Power-to-Heat: Converting Power (Surpluses) into Heat and Replacing Fossil Fuels

Name the most relevant PtH technologies providing space and process heat.

Answer 8

Power-to-heat

Space heat

• Central
  –> District heating
  –> Industrial heat pumps
• Decentral
  –> Heat pumps

Process heat

• Induction heating
• Conductive heating

Question 9

Name the different types of storages, the type of energy they store and provide an example for each.

Answer 9

Electrical storage

• Electrical energy
• E.g. capacitor, inductor

Chemical storage

• Chemical energy
• E.g. hydrocarbons

Electro-chemical storages

• Electro-chemical energy
• E.g. batteries

Mechanical storages

• Kinetic or potential energy
• E.g. pump hydro storages, compressed air reservoir

Thermal storages

• Thermal energy (heat + coldness)
• E.g. latent or sensible heat storages