Is affordable, 24/7-reliable, electricity ever possible again?

Too good to be true? What do the physics tell us?

There's no such thing in the real world as a perfectly efficient machine. Efficiency losses are always a practical reality. For 'pumped hydro' systems, where renewables pump the closed-cycle water uphill, these losses are large. Is the all-up net energy supplied less than 20-30%?

There are energy density realities here. Using USA measures, gasoline power is one billion times more energy dense than wind and water power. It's ten quadrillion times more energy dense than solar power. To store the energy contained in 1 gallon of gasoline requires over 55,000 gallons of water to be pumped up 726 feet (and that's assuming 90% recycling process efficiency).

Whatever the efficiency of a closed 'pumped hydro' power system, using renewables to pump water uphill will require massive extra renewables generation capacity. That means much more demand pressure on the already-stretched grid in the NEM.

And yet a major 'pumped hydro' scheme is being developed within the Snowy Hydro system. It's called 'Snowy 2.0'. Other such schemes have been proposed by politicians elsewhere.

Snowy 2.0 is already way over the initial budget, up from A$2 billion to A$12 billion and counting. Almost certainly, costs will rise further. It's also way behind schedule. First power to the grid was supposed to be produced in 2024. 2030 now seems very much a best-case scenario. The tunnel borer (named Florence) developing this system seems regularly to get bogged and hasn't got very far.

And what could Snowy 2.0 do if it eventually operates as planned? The claim is it can power 3 million homes for a week. Every single week all the time, in all seasons and all weather? I don't think so. If powered by renewables, it will need time off for intermittent power to pump water uphill again. Or would Snowy 2.0 need many, many more extra batteries to store intermittent renewables power?

Proponents call Snowy 2.0 nation-building. I don't agree. It's very, very high-cost power at best.

Demand response. This is a euphemism. It's electricity rationing. It does not make power more affordable or more reliable. It makes it unavailable. It can start today. It already has. This is renewables power supply failure in its clearest, arguably most painful, form.

'Green' hydrogen? Electrolysis to produce hydrogen requires lots of very pure water (9kg for every 1kg hydrogen). Water purification requires lots of energy. 'Green' electrolysis requires huge inputs of extra renewable energy. Yet more power demand pressure on the grid?

If 'green' hydrogen can be produced and used intermittently, very large increases in renewables generation capacity will still be needed, even if storage requirements are reduced.

If hydrogen use is for continuous manufacturing processes (eg, 'green' steel), many, many more batteries will be needed for storage, too.