Storing Green Energy

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Mrs SG and I are big fans of green energy. We have as many PV panels as we could cram on our roof, and they generate an average of 18kWh/day. That varies a lot through the year, of course. At the moment they are managing 10kWh/day, but the midsummer record is 31. As it happens today is the 9th anniversary of the panels’ installation and their total output has been 60,831kWh. I estimate the financial return on our investment to have been 8.8%pa – not taking into account depreciation (the system will probably outlive Mrs SG and me), the public subsidy or the value of carbon credits that we had to sign over to the installer.

We don’t have a battery though. When we have surplus production we sell it to our French-owned supplier (on average 6kWh/day) and when we’re running our centralised heating/cooling system we buy to make up our deficit at more than three times the price at which they buy from us.

Tesla Battery – the biggest in the world when it was built in South Australia

Some people talk glibly about large-scale battery storage to solve the problem of intermittent output from solar panels and wind turbines, but the cost of this strategy is not sidely understood. AGL (an Australian company that generates and distributes electricity, and has been characterised by Greenpeace as the country’s biggest emitter of greenhouse gases) has commissioned a huge Li-ion battery to be built on Torrens Island, South Australia. It will have capacity for 250MWh and cost A$180M (US$130M at the present rate of exchange). The capital cost is therefore A$720/kWh (US$520/kWh). Feel free to check the maths in case I’ve made a mistake.

Our car – an average-sized petrol-driven sedan – has a fuel tank that holds 51 litres. 1 litre of petrol contains 8.8kWh of energy. Therefore the cost of a Li-ion battery with the energy capacity of our fuel tank would be 51 × 8.8 × US$520 = US$233,000. This is an order of magnitude more than we paid for the car.

So how does AGL think it can make money from this huge battery? The answer lies in the magic of the free market, which now prevails in Australia thanks to the fragmentation and privatisation of what used to be a publicly-owned monopoly. According to the Australian Energy Market Operator (AEMO) the average wholesale price of electricity in 2020-21 ranged from A$0.045/kWh in Tasmania to A$0.072/kWh in NSW. At these prices AGL would have to fully charge and discharge its battery at least 4 times a day to turn a profit.

Nuclear: the clean, green political no-no

But, due to wildly mismatched supply and demand profiles, on 22 occasions last year the market price of electricity spiked about A$5/kWh. That’s not a misprint: five dollars per kWh!  So AGL will keep its powder dry until there is a sudden extreme shortage and then sell the contents of its battery to the highest bidder.  If the whole battery is emptied at A$5/kWh (which is nowhere near the maximum price, mind) AGL will receive a windfall of A$1.25M. At its maximum discharge rate the battery will empty in an hour.  Great for price spikes and short-term outages, but it’s not like having a hydro-electric dam full of water.  Hence the need for:

  • Snowy Hydro 2.0 – pumped storage for 350GWh (1,400 times more than AGL’s battery) that’s expected to take 8 years to build and cost at least A$5bn. That’s equivalent to US$10/kWh, about midway between our petrol tank and AGL’s battery on a logarithmic scale.
  • Back-up dispatchable power (available at the push of a button) from some other source. The Government favours natural gas, of which Australia has an abundance; green voices propose biomass; some contrarians suggest nuclear power, which is a political no-no at the moment.

That’s all. There’s no punchline.

Australian Liberals

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Here’s a letter I wrote to my MP, who happens also to be a Minister in Australia’s Liberal-led Commonwealth Government. I have just received a stock answer.

Dear Christopher,

As one of your constituents and a Liberal voter since I came to Australia in 1978, I have to tell you of my growing disenchantment with your party, to the point where I feel I can no longer vote for it.

I would like you personally to remain in Parliament and on the front bench, whether in government or in opposition, but the ongoing factional civil war and our new PM’s antics have me in despair. First there was the lump of coal in Parliament, now we’ve had the abandonment of the NEG, the refusal to take a stand on climate change, the description of the country’s most iconic building as a ‘billboard’ and – the last straw for me – the news that Mr Morrison is considering moving our Embassy in Israel from Tel Aviv to Jerusalem!

I know we have to trot submissively at President Trump’s heels to some extent, to keep our place under the USA’s nuclear umbrella, but to kowtow to a rogue state whose disregard for humanitarian principles and international law matches Russia’s or China’s, and to take sides against some of the most oppressed and dispossessed people in the world… well, words fail me.

And is it really only a device to curry favour with the 13% of Wentworth voters who are Jewish, as I heard on Radio National this morning? Is our foreign policy being driven by short-term electoral gaming? If so, I’d rather give Penny Wong a go.

I don’t usually send off an email while I’m still angry; I prefer to wait, re-read and edit. But not this time. I suspect my anger will only grow, so I might as well shoot this off now.

With good wishes to you, if not to your party or its present leader…

John Standingford
Linden Park
https://StroppyGit.com
16/10/18

Explanatory notes:

In February 2017 Scott Morrison brought a lump of coal into Parliament as a prop for a speech promoting the continued mining and burning of coal in spite of its alleged contribution to climate change.

NEG was the National Energy Guarantee, the closest thing to an energy policy that Australia has had for many years. It resulted from hard negotiations between parties that put energy prices ahead of decarbonisation and vice versa, Federal and State Governments, industry and consumers. Scott Morrison dumped it as soon as he became Prime Minister.

Wentworth is the constituency where Malcolm Turnbull, the deposed PM, had a 17% majority. The Liberal-led ruling coalition had a 1-seat parliamentary majority and was desperate to retain the seat after Turnbull’s resignation. They lost it to an independent. Coincidentally a TV serial called Wentworth is running at the moment. It’s set in a women’s prison and shows brutality almost on a par with what’s going on in the Liberal Party.

Penny Wong is the Shadow Foreign Minister – fair-minded, level-headed and popular.

Forty Thousand!

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No wonder the Sun has been an object of worship! Today our solar panels reached another meaningful milestone: meaningful to us roundists, anyway. Forty is a special number: forty days and forty nights, life begins at forty, the roaring forties, Ali Baba and the forty thieves, forty winks… But raise it by three orders of magnitude, and you have something grand!

And I remember a popular song from the forties – or maybe the fifties, but it fits my narrative better if it was the forties. The song was about 2-year-old Johnny Brown’s impressive cockney utterance: “Faw’y Fahs’nd Fevvers on a Frush!”

Billy Cotton delivering his trademark “Wakey-wakey!”

I knew about feathers and thrushes, and I knew about big numbers, but for some reason I always heard ‘frush’ as ‘brush’ and assumed that bristles could also be referred to as feathers.

The song was written by Paul Boyle and Eddie Carroll, of whom I know in no other context, and was popularised by the great Billy Cotton in the equally great Billy Cotton Band Show on the BBC Light Programme.

“Temperatures could halve…”

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I just read this headline in an Australian newspaper: “The mercury could plummet by as much as half this weekend.” In the same story was the caption: “Temperatures could halve in some places.”

This is stroppy-making balderdash!

Having read the article it was clear that its author was referring to a drop from 20°C to 10°C. If the Fahrenheit scale were used, the drop would be 36%, not 50%. But the only sensible scale to use in this way is the Kelvin scale, in which zero corresponds to absolute zero – colder than which it is impossible to go. On that scale the drop would be a mere 3.4%. That wouldn’t make much of a headline, would it?

This isn’t an isolated instance. Journalists seem to lack basic scientific understanding, and their sub-editors are more interested in concocting clever puns (“Lion Park Roaring Success”) than ensuring accuracy.

Here’s another example. Elon Musk is going to build the world’s biggest lithium battery in South Australia, my home state. It has been variously described in the press as a 100MW battery and a 100MWh battery. The former makes no sense. A watt is a rate of flow of energy. A watt-hour is a unit of energy analogous to a volume of fuel. In fact 1 litre of diesel oil contains about 10,000 watt-hours (or 10kWh) of energy.

This is not actually me

An aside…

When I use the rowing machine at the gym I can maintain an energy flow of about 140W (or 0.14kW). So if I rowed for a living, selling the energy I generate for 23 cents per kWh (which is roughly what I pay for electricity in my home) I would earn 0.14 x 0.23 x 40 = $1.29 for a 40-hour week.

Roundism, Patterns and Solar Power

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Last year a posted my thoughts on roundism – our obsession with round numbers: special birthdays, wedding anniversaries and the like. So I thought, “When the meter that records the cumulative output of our solar panels reaches 25,000, I’ll photograph it and put up another post.”

But I missed it. I estimated when the meter would hit 25,000 and then I forgot to go to the garage with my camera.  So I thought, “I know, I’ll wait for 25,252 and do a post about our obsession with patterns and palindromes – and put in a plug for solar power.”  And this time I didn’t forget!

Solar25252_20160322

Solar panel against blue sky

Our 3 kW array of photovoltaic cells was installed on my late mother’s 100th birthday, so I can’t forget the date and I know we’ve been harvesting the sun’s energy for 1,301 days.  That means we’ve averaged 19.4 kWh per day, earning/saving us close to A$6 per day.  That’s like having over A$90,000 invested in 20-year US treasury bills.  And the system cost us only A$6,800, so that’s pretty good.

Power

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Yesterday I rowed 500m – not on an actual lake or river, but on a rowing machine in a gym. I rowed hard and was panting at the end.  My average power output was 152 watts.

Were I able to row like that for 8 hours per day, six days per week, my output would be equivalent to 5% of the electrical energy that Mrs SG and I consume.

If my efforts were rewarded in cash, at a rate corresponding to the average price we pay for electricity, I would be earning about US$2 per week. Maybe electricity is not so absurdly expensive after all.

So why am I stroppy? Because a calculation like that makes me feel feeble and inadequate!