Renewable energy only as good as its backup power

With fears that higher electricity prices will follow after the closure in 2023 of AGL Energy’s Liddell coal-fired power station in NSW’s Hunter Valley, Scott Morrison’s plan for a gas-fired power plant to replace Liddell appears to have merit (“Power up or we build gas plant”, 15/9). But as former resources minister Matt Canavan says, building a gas-fired power plant in the middle of one of the world’s greatest thermal coal basins doesn’t make a lot of sense (“Nats arc up over future of coal”, 16/9).

Morrison says the reason he is backing the gas plant is because it could be put in place in 18-24 months, whereas a coal-fired power station would likely face lengthy approvals delays. John Durie suspects Morrison’s hidden message behind his gas plan is an admission that the future is renewables and gas is simply a transition mechanism (“Game of bluff’s takeaway: the future is renewables”, 16/9). Voters could be forgiven for suspecting that a gas plant built in time for the 2022 federal election is the reason for the PM’s decision.

In any case, Morrison should level with the people on the future of cheap, reliable coal-fired power. Does he believe it should remain the driving force behind the economy, job security and our way of life? If he does, what is his long-term plan for coal?

Dale Ellis, Innisfail, Qld

Those who like to lecture us on the virtues of renewable energy should take a good look at what is happening in California. This state has been closing down its nuclear plants and replacing them with solar farms and wind arrays since the 1970s. Only the Diablo Canyon nuclear plant remains, but not for long.

In the face of this latest heatwave the grid has been unable to cope with demand, resulting in blackouts and power rationing. The population is discouraged from using airconditioning in temperatures of up to 46C.

Renewable energy is only as good as its backup power system, owing to its unreliability and its low-energy density. This is a major contributor to its high cost and the requirement for heavy taxpayer subsidies to make it viable. California has among the highest electricity charges in the US.

Parallel to the closure of nuclear plants, carbon dioxide emissions in California have actually increased with the expanded adoption of natural gas backup. Even the gigantic Ivanpah solar farm in the Mojave Desert has to be primed every day with natural gas.

With decreased reliability, increased cost to consumers and increased emissions, renewables have been a disaster for California. It is no wonder people are fleeing this once-prosperous state in droves.

Christopher Murphy, Mundingburra, Qld

AGL is proposing to replace the 1680MW coal-fired generators at Liddell with a 500MW battery. The coal-fired generators at Liddell can supply 1/20th of the grid continuously. A 500MW battery could supply 1/20th of the grid for 20 minutes. It would then need to be recharged. AGL wants to replace the orchard with a single piece of fruit — a lemon.

Colin Davidson, Fadden, ACT

Stop toying with cosmetic solutions for electricity, think big and construct a 3000MW thermal power station on the Hunter Valley coal face to replace the 2000MW Liddell power station, thus taking advantage of existing easements /transmission networks.

Rex Womersley, Cairns, Qld

I refer to your editorial “Morrison energy plan’s focus is ‘stuff that works’” (16/9). Proponents of a “gas-led recovery” from the COVID-19 crisis overlook major problems with gas as an energy source. Both natural gas and coal seam gas are composed largely of methane, a global-warming gas that is about 30 times more potent than carbon dioxide on a 100-year timescale, and 100 times more potent than CO2 on a 20-year timescale. Large amounts of methane “fugitive emissions” escape unburnt into the atmosphere during the extraction process, especially if this involves fracking, and during transport to power stations and export terminals.

According to Bloomberg New Energy Finance, renewable energy was cheaper than energy from new coal- and gas-fired power stations back in 2013. Bloomberg showed that electricity from a new wind farm costs $80 per megawatt-hour compared with $143/MWh from a new coal plant, or $116/MWh from a new baseload gas plant. Alas, gas is not the answer.

Douglas Mackenzie, Deakin, ACT