Superconducting Magnetic Energy Storage-- A Solution to the Energy Crisis

Weijia Yuan1, M. Husband2 and T. A. Coombs1

1Engineering Department, University of Cambridge, UK2Rolls Royce inc., Derby, UK

1. Energy Crisis 2. Introduction of superconductivity

3. Superconducting Magnetic Energy Storage - what is it and why is it better ?

4. Cambridge Uni’s prototype SMES

[1] ABB Inc., Energy efficiency in power grid[2]Hassenzahl etal, Electric power applications of superconductivity, IEEE trans on appl. supercon. 92(10) 2004[3] Xue etal, A study of the status and future of superconducting magnetic energy storage in power systems, Supercond. Sci. Technol. 19(6) 2006

5. Broader applications of SMES and superconductivity for UK

Type of storage Relative delivery time (%)

SMES 0.1-1

Batteries 100

Pumped hydro 100000

Flywheel 10

Batteries

Flywheels

SMES

Capacitors

Comparison of cyclic efficiencies Comparison of energy delivery time Comparison of energy and power densities

Acknowledgement: This project is funded by Rolls Royce plc. and Cambridge Overseas Trust.

20% wasted energy

A superconductor carries a large current without any resistance. A superconductor can operate with liquid nitrogen, which is even cheaper than milk. A superconductor is a ‘green’ material by reducing energy losses and hence carbon emissions.

A ‘fat’ copper bar carries 240 A with 8% energy loss

A ‘slim’ superconductor carries 240 A without any loss

Superconducting Magnetic Energy Storage (SMES) systems store energy in the magnetic field created by the flow of current in a loop. They can be used an infinite number of times.

SMES has an almost 100% cyclic efficiency SMES can deliver energy faster than other storage methods

SMES has the best balance between energy density and power density

A simulation model was developed to analyse the operation of the system

Current density distribution Magnetic field distribution

A prototype superconducting coil was made.

100m of superconductors were used.

This coil can store several kJ energy and provide 1 kW power.

A prototype SMES system was integrated It can improve the stability of a power

system It can supply large pulsed power for

aircraft and ships

Combining with superconducting machines, SMES is a compact way of supplying large pulsed power for aircraft, ships and other machines.

SMES can integrate off-shore wind turbine and tidal generators with the main power grid together with superconducting cables.

20% of energy is wasted during the generation and transmission of electricity. Since they have no resistance and are able to save a large amount of energy, superconductors will bring a more fundamental change to electric power technologies than has occurred since electricity use became widespread a century ago. Superconducting Magnetic Energy Storage (SMES) systems will help bring cleaner energy.

a superconducting machine

SMES a wind turbine SMESsuperconducting cables

Nearly 20% of energy is wasted during the generation and transmission of electricity. The wasted energy worldwide per year is 1 billion MWh, which is worth £50 billion, equivalent to 3.5% of the total energy consumed by US, and 180 million tons of CO2 emissions.

£50 billion 180 million tons of CO2

Superconducting coil

Control

Protection Refrigerator

current

Main power output

SMES