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What is base load?
What is not base load?
What will be needed in the future?
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Base load power: the facts

In September 2017 the Australian Government proposed extending the life of the Liddell coal-fired power station by a further five years. The highly polluting power station is 46 years old and due to be shut-down in 2022. The owner/operator, AGL, has criticised the government's move as foolish.

The justification for this bizarre move was a claim that Australia needs the base load power that stations such as Liddell supply.

This page aims at debunking the claim that Australia needs more base load power to replace the coal-fired power stations that are reaching the ends of their lives.

It also aims to make clear what forms of power are, and are not, base load. There has been a remarkable amount of ignorance on this point among people who have been in positions where they had a responsibility to learn the facts.

This page written 2017/09/07, modified 2017/10/02 – ©
Contact: email daveclarkecb@yahoo.com (David K. Clarke)

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The ideal power station

The ideal power station would be available all the time, would produce low-cost emission-free electricity, and would be able to increase and decrease its generation quickly to follow the variation in demand.

The ideal power station does not exist.

What is base load power?

Wikipedia defines base load power as:
"The base load on a grid is the minimum level of demand on an electrical grid over a span of time, for example, one week. Base load power sources are power stations which can economically generate the electrical power needed to satisfy this minimum demand."
So base load power stations are those that produce power cheaply at a steady, or near steady, rate. Coal and nuclear power stations, which are unable to quickly, easily and efficiently change their output to fit the variation in the demand on the power grid, are well suited to provide base load power.

A solar thermal power station with molten salt energy storage
Sundrop Farms
Sundrop Farms solar power supply, Port Augusta, South Australia.
The molten salt tanks used for energy storage can be seen at the foot of the power tower.
A solar power photo-voltaic (PV) power station
Mugga Lane
Mugga Lane, Australian Capital Territory
A wind farm
Hornsdale, Mid-North South Australian
Much more valuable is "peaking power"; the power that can be provided at short notice, and reduced at short notice, to allow the supply on the power grid to respond to the variations in the demand for electricity that is happening all the time.

With the rise of renewable energy there will be less and less need for base load power and more and more need for peaking power.

What is not base load?

Power that is available at short notice is not base load, it is peaking power and is much more valuable than base load power.

Hydro power is not base load, it is available as required within the limits set by long-term rainfall.

Pumped hydro is not base load, it is readily available energy storage suited for storing large amounts of energy. Its availability is not limited by rainfall because it uses the same water over and over again.

Batteries do not provide base load, they also provide readily available energy storage, available at even shorter notice than pumped hydro. As of the time of writing, 2017, batteries cannot store the large amounts of energy that pumped hydro can. Batteries can also provide valuable grid services.

Solar thermal is not base load; it provides energy as required within the limits of available sunshine. It typically has several hours storage.

Obviously wind power and solar PV do not provide base load power.

What will be needed in the future?

More base load power will not 'keep the lights on' in Australia. Coal and nuclear can provide base load power, but they are not able to quickly change their rate of power generation to match the changing demand in a power grid; for that we need more peaking power, such as pumped hydro energy storage and solar thermal with energy storage.

The Liddell power station closure is not scheduled until 2022. This is five years off at the time of writing. In this time the Australian power supply mix will change greatly and the need for base load power will decline substantially. In these five years:

  • Many hundreds of megawatts of wind power will be built;
  • Many hundreds of megawatts of rooftop solar PV power will be built;
  • Many hundreds of megawatts of utility scale solar PV power will be built;
  • Some solar thermal power stations with energy storage will be built; many could be built;
  • Many hundreds of megawatts (MW) (and megawatt-hours, MWh) of battery storage will be built;
  • Many hundreds of MW and MWh of pumped hydro energy storage could be built;
  • Electric vehicles will become much more common (they can be charged when generation is abundant and power demand is low);
Other energy storage methods are undergoing development and testing, such as the power to hydrogen trial in South Australia in late 2017.

On current trends Australia will have far more renewable power five years in the future than it does in 2017. Much of this power will be available only when the wind blows or the light is bright (direct sunlight is not needed for solar PV power generation).

There will be a strong need for peaking power to fill the gaps when the renewables are not generating sufficiently to fill the demand. (In the longer term energy storage, most economically pumped hydro, will fill much more of this need.)

Diesel is easily and cheaply stored for long periods. Diesel powered generators, that will only be needed a small percentage of the time, will be ideal for the needed rare peaking power in exceptionally high demand times in the short- to medium-term. South Australia is planning to use diesel generators to fill this need for peak demand in the summers of 2017/18 and 2018/19.

Related pages

On this site

How should Australia generate its electricity?
South Australia's success with renewable power
Mid-North South Australia, leading the nation in renewable energy
Northern SA's renewables
Wind power in Australia
Impressive renewable energy developments in Australia
Pumped hydro power
Glossary of technical terms relating to wind power

Climate change
Climate change disasters and the Australian government's actions
Greatest crime in history
Major threatened disasters compared
The end of coal
Killer coal
Coal seam gas: an environmental disaster
The Turnbull Australian Government

On the Internet

A glossary of the energy debate; The Conversation.
Renew Economy; AGL ridicules Coalition request to keep Liddell [coal-fired power station] open extra 5 years.
The Conversation; Why coal-fired power stations need to shut on health grounds.
More coal doesn't equal more peak power, Alan Pears, The Conversation, 2017/09/13.

The big three Australian power generators see no future in coal

AGL's statement on the Liddell closure.
Energy Australia boss says there are much better options than keeping the old Liddell coal-fired power station running for a few more years.
Origin Energy boss regects coal