What Is Base Load Power

Whenever conservatives argue against the introduction of renewable energy, they talk about “base load power” and the inability for renewable energy generation such as wind and solar to supply base load power.

Former Federal Liberal PM Tony Abbott:
“The only way we can have reliable baseload power is through coal and gas, particularly coal.”

Minerals Council of Australia (MCA):
“The MCA has highlighted that generators which provided 66 per cent of low-cost baseload power in 2016 will retire between now and 2030.”

Federal Liberal MP Craig Kelly:
“In Australia we need to get at least one or two of these [coal-fired power stations] built to ensure there’s enough baseload power in the grid.”

Firstly, solar and wind generation has nothing to do with base load. Secondly, there are only two sources of energy generation that are concerned with base load, coal and nuclear. Thirdly, base load is not the baseline of consumer demand or the minimum continuous demand from consumers.

Let’s Start at the Beginning

When Australia was expanding its grid in the fifties, sixties and seventies, we built large coal fire power stations that were never meant to be turned off. They were to be run continuously regardless of demand. And why not; we had plenty of cheap coal and these coal fire power stations were the cheapest option.

The idea was that as the demand rose during the day you could increase the output from those generators, because they wouldn’t be operating at full capacity (intermediate demand, see diagram). If demand for electricity went above the generating capacity of the coal fired generators, we would look at “peaking power” generators like gas or hydro generators to meet the excess demand.

Base-load power stations, especially coal-fired and nuclear, are generally cheap to operate, but their capital costs are high. So, they cannot be used just to handle peaks in demand. To pay back their high capital costs, base-load power stations must be operated as continuously as possible. A faster, cheaper, more flexible type of power station is needed to complement baseload and handle the peaks. Peak-load power stations are designed to be run for short periods of time each day to meet peaks in demand e.g. gas.

Coal-fired power stations can take days to fire up from cold to full capacity and when demand slumps during off-peak periods, shutting down isn’t an option. This is why off-peak electricity charges came into being. Rather than having to shut down power generation at night when demand falls, operators offered very cheap electricity to consumers so they could heat the hot water in their hot water systems. This sustained the “base load” of the power station. Professor Anthony Vassallo holds the Delta Electricity Chair in Sustainable Energy Development at the University of Sydney. “The baseload, that is the lowest load on the generators, is met at 4 a.m.,” Vassallo continues. “At that time of the day the idea is that the cheap fuel generators, the coal-fired generators, would be ticking over, just meeting that minimum demand.”

Symons power usage graph

Symons power usage graph

“If the demand dropped even more, some of the big generators would have to turn off, which is very inefficient. So, there were schemes like off-peak hot water to provide extra load and use the generator power that was available at that time of night.”


Today we have renewables such as wind and solar feeding into the grid. This means that in the early hours of the morning, when the coal fire power stations are working at base load and wind turbines are generating electricity there is an excess of supply and prices for energy drop. It sometimes drops so low that spot price for electricity is zero dollar or less. In turn, coal fire power stations are forced to pay to keep their turbines running. Big Coal has to pay for people to use their electricity.

But as the day moves ahead solar power joins wind power to increase the supply of electricity to the grid. Overtime, as more and more renewables come on line, the grid develops a dip in the middle of the day and we end up with a graph that looks lot like a duck (see Duck Curve diagram), with its tail representing the demand increase as we get up in the morning, a dip in the middle of the day and the head being the increase in demand in the evenings.

CSIRO Energy Director Dr. Glenn Pratt describes the old baseload generator as an “anachronism” in a modern electrical system. According to Dr. Pratt, “It’s entirely possible to operate electricity systems without baseload electricity generation. It’s technically challenging, but it’s certainly possible.”

Symons duck curve

Symons duck curve

“Technology has moved on from base load, and now you want flexible power. And that’s what demand management, batteries and pumped hydro is,” says Professor Andrew Blakers, director of the ANU Centre for Sustainable Energy Systems.

I can hear the conservatives now, “What happens when the wind does not blow and the sun does not shine?” According to Dr Mark Diesendorf from the University of New South Wales, “All this talk about ‘you’ve got to have baseload power stations’ is complete nonsense,” Dr. Diesendorf’s team has run thousands of computer simulations correlating hourly power-consumption data from the National Electricity Market (NEM) in 2010, with the potential power generation of renewables, based on recorded weather data for the same year.

Diesendorf claims that a combination of existing technologies, including hydro and biofueled gas turbines, were able to supply the simulated NEM even during “peak demand” — on winter evenings following overcast days. “No single one does all the job… You probably
need a mix of hydro, which may include off-river pumped hydro, and possibly open-cycle-gas turbines,” he says.

Renewables are now cheaper than any other form of generation. If you look again at the “duck shaped demand graph”, it is easy to understand that the key is energy storage; pumped hydro, hydrogen, batteries etc., Storage will cut of the head and the tail off the duck dramatically increasing supply and drastically reducing the price of electricity.

Author : Kosta Symons

Published Date : February, 24 2020

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