Developments in Energy Storage Technologies

Name the developments in energy storage technologies:

• Peak shaving using Pumped-Storage HEP

• Rechargeable batteries

• Fuel cells

• Compressed gas

• Types of Storage Systems

• Peak shaving using Pumped-Storage HEP

1. Surplus electricity is used to pump water from a lower reservoir to a higher one

2. The energy stored as gravitational potential energy

3. Water is released when there is an increase in demand

4. It is rapid response

• Rechargeable batteries

Batteries that enable the original chemicals to be reformed using electricity so that the batteries can be reused

What factors affect rechargeable battery viability?

Energy density

Cost per unit of energy stored

Recharging speed

Examples of rechargeable batteries

Lead acid

NiCad (Nickel-cadmium)

• Fuel cells. What is a fuel cell?

Am electrochemical device the produces electricity from a chemical reaction (usually between hydrogen/alcohol and oxygen.

What do fuel cells require?

They require new fuel and oxidant chemicals to continue to operate

• Compressed gas

Surplus energy can be used to drive a pump that compresses air.

Compressed air can be released later to power machinery.

Where do large scale systems get their compressed air?

Underground caverns like in salt mines

How much power could large scale air compression systems produce?

200 MW

What can compressing the air also produce?

Heat

How are compressed gas systems made efficient?

The system will have a heat storage. This can recover over 90% of the original energy.

• Types of Storage Systems

• Thermal storage

• Vehicle to grid systems (V2G)

• Power to gas systems (P2G)

• The ‘hydrogen economy’.

• Thermal storage

• Heat energy is lost through conduction, convection, and radiation, making long-term thermal storage difficult.

• However, short-term storage can be efficient using molten salt, high-volume water, or high thermal mass materials

• They all have a high specific heat capacity, so the greatest possible amount of heat energy can be stored in a given volume

• Vehicle to grid systems (V2G)

• If vehicles are parked for long periods, then they should be plugged into the grid

• Peak in demands for electricity mean that a small proportion of energy from the vehicle battery may be used

• Surplus energy can then be used to recharge vehicle batteries

Why is the Vehicle to Grid system good?

Avoids the cost and ev impacts of using rapid response-low efficiency-high cost power stations such as “Open Cycle Gas Turbines”

• Power to gas systems (P2G)

Surplus electricity is used to produce gaseous fuel which can be stored

• It does this by using the surplus electricity to electrolyse water, splitting it into hydrogen and oxygen

• Hydrogen can be used to produce methane that can be fed into the natural gas pipe network

• The ‘hydrogen economy’.

The hydrogen economy is where surplus energy is stored as hydrogen, then used during high demand or low supply.

Storing excess energy helps manage intermittent energy supplies like solar and wind.

Why hydrogen?

Unlike many renewable energy resources, hydrogen has a high energy density and therefore could replace fossil fuels for many uses (such as powering vehicles)

What is a benefit to the hydrogen economy?

It reduces the energy losses created during energy conversions.

• If primary energy were converted directly to produce hydrogen, it reduces energy losses that would take place during multiple energy conversions.

What could the stored hydrogen power?

• Heating

• Vehicles

• Steam-turbine power stations

• Fuel cells to generate electricity.