Base load power is a term we're hearing a lot in discussions about our energy future. But what does it mean, and is it really relevant?

Because wind and solar are intermittent, the argument goes, we need a constant power source chugging away in the background to cover supply when the sun goes down and the wind stops.

Key points: The 'base load' concept is misinterpreted and outdated

The 'base load' concept is misinterpreted and outdated Demand varies hugely and energy production needs to be responsive

Demand varies hugely and energy production needs to be responsive Hydro can be used to balance intermittent solar and wind

But energy researchers say the term is a "dinosaur" that has been misunderstood, and that it no longer applies to our dynamic energy market.

What is base load power?

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.

So when these power plants were being built in Australia, a market solution was created, says Professor Anthony Vassallo, Chair of Sustainable Energy Development at the University of Sydney.

"In the 70s, to stop them from having to turn off overnight, the regulators and the operators offered very, very-low-cost electricity for consumers to run their hot-water systems, which in turn sustained the 'base load' on the power station," he says.

"[Base load] refers to the minimum level of output that these big power generators could go to, before they turned off."

But today, as more and more renewables such as wind are feeding the grid, coal-fired power stations are often forced to pay to keep their turbines running when demand drops.

Coal-fired power stations have been forced to pay to keep supplying to the grid. ( ABC News )

"At night when wind in some areas is generating a lot [of power], it's the coal-fired stations that don't get dispatched and the price can drop negative — below zero dollars — and so the big [coal] generators end up having to pay for people to take their electricity," Professor Vassallo says.

If not base load, then what?

Researchers argue that this "base load" of supply from coal-fired power stations has been falsely translated as a baseline of consumer demand.

"The idea of there being an average or 'base' electricity load, doesn't make sense. Let alone having this sort of big, slow-changing power station to meet that load," says CSIRO Energy Director Dr Glenn Platt.

"Things are much more dynamic and the difference between the minimum and the peak amount of electricity we use is huge these days."

Throughout the day, electricity demand peaks in the morning as people get ready for work, and again in the evening.

But electricity use also changes across the year, with huge differences between hot summer days, when air-conditioners are at full blast, and mild spring nights — with particular lows at unusual times like Christmas night.

"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.

Researchers say hydro can balance intermittent wind and solar supply. ( Supplied )

"If you have an increase in demand, a coal power station will take hours [to meet it], a gas turbine 20 to 30 minutes, batteries about a second, demand management about a second, and pumped hydro will take anywhere between 20 seconds and two minutes."

Researchers say a combination of these rapid response, dynamic power sources is the future of power generation.

What about when the sun doesn't shine and the wind doesn't blow?

"All this talk about 'you've got to have baseload power stations' is complete nonsense," says Dr Mark Diesendorf.

"It's a dinosaur."

His team at the University of New South Wales ran "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.

He claims that a combination of existing technologies, including hydro and biofuelled 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.

"For those of us who work in the field, this is very straightforward now. But the barriers aren't primarily technological."

Professor Blakers agrees. He says that Australia's energy future lies in solar and wind, with pumped hydro as a balancing source.

"Pumped hydro is 100-year-old technology, completely off the shelf, and importantly you can get these pumped-hydro sites built before 2022," he says.

"A recent study that we published shows that there's about 22,000 [potential] pumped-hydro sites on the east coast. We only need 20 or 30 of them."

A more connected energy grid

"The question isn't really a case of can you do it; it's a question of what cost," says Dr Platt.

Regardless of the energy mix, the researchers agree that a much greater capacity to transmit power across a connected grid is essential for a future dynamic energy system to work.

"It would be very, very good to join South Australia by transmission line directly to New South Wales... It would make the whole national electricity market a more stable system," Dr Diesendorf says.

"It's this long, skinny system — 5,000km long. Putting in one or two cross-links would benefit the whole system, but you can't do that overnight."

None of these researchers are under any illusions that a transition to a dynamic energy system will be cheap.

It will involve investment in infrastructure, across state borders, and a forward-thinking approach from our political leaders.

And leaving base load power in the past, they all agree, would be a good place to start.

Editor's note (20/11/17): This story was changed to reflect that times like Christmas can cause power demand to dip even lower than seasonal fluctuations.