There’s a cuckoo in the Woods [Updated]

Yellow-billed cuckoo

Jonathan Young was back on the hunt for answers from Megan Woods, the Minister of Energy and Resources, after her answers to his questions yesterday left him (and all thinking people) deeply unsatisfied. Quote.

So when the Minister said yesterday “this Government is intent on building a resilient energy system with more resilient forms of renewable energy.”, how many megawatts of new renewable generation will be needed to reliably replace coal, gas, and diesel generation? End quote.

Nice simple question that could have a one sentence answer. “xxx MW”. Did he get that answer?  No, of course not.   Woods rattled on about how much extra electricity generation would be needed by 2050 and told us it was, Quote.

… a very achievable target of around the equivalent of 4.5 wind farms per year…. End quote.

4.5 wind farms per year!  My recent post about covering Taranaki in wind farms was a little tongue-in-cheek. It appears I was not joking after all; Woods said the first one was being built in Taranaki.

As Woods had not answered the question there was a bit of back and forth with the Speaker and Brownlee getting involved and Woods was told to answer again.

So Woods simply repeated the first non-answer.  Realising Woods had no clue what the answer was, Young pressed on: Quote.

Well, how can New Zealanders be confident in her assurances that there will be no energy supply gap when she doesn’t even know what investment is needed to achieve that assurance? End quote.

And that is when we disappeared into cloud cuckoo land. Quote.

WOODS: We can have confidence because, as I talked about in the reading of the legislation yesterday, there is a large body of evidence that shows that impediments to the transitions to renewable aren’t either financial or technical. They’re around political will, and this Government doesn’t lack in that. That member can have great comfort in the fact that in this country, we have hundreds of megawatts of consented but not yet built renewable energy. We also know that technological change to store the roughly 6 terawatts of surplus energy we produce in summer that we can use in winter is coming not just through battery power but through things like molten salt, like hydrogen, and a range of other storage facilities. I invite that member to join the 21st century. End quote.

The salvation for New Zealand is going to be storing the 6 TW of spare summer generation for use in winter.  I presume that the Minister really meant 6 TWh as that is energy rather than just 6 TW which is power.  We will run with the assumption that the Minister of Energy and Resources understands the difference between energy and power and simply left the “hours” off as shorthand.

6 TWh of energy storage for up to six months using “not just through battery power but through things like molten salt, like hydrogen, and a range of other storage facilities”

Working backwards through the list:

“a range of other storage facilities”  Like watt? (Sorry!) There is more than one in her potential list; she has a ‘range’ of them.  One, presumably, might be pumped hydro.  Build a big dam somewhere, spend the summer pumping water uphill into a lake behind the dam and then generate electricity in the winter by running the water down through the turbines.  Will the Greens let them create a huge artificial lake that has massive six-monthly fluctuations in water level?  My guess is – No.

Other storage facilities?  Compressed air, flywheels, moving weights up a slope?  Who knows? Are they commercially viable? What is their efficiency rating?  Will they store 6 TWh for up to six months?

Hydrogen:  “The storage of large quantities of liquid hydrogen underground can function as grid energy storage. The round-trip efficiency is approximately 40%.” Providing we can source a supply of taniwha free caverns and the needed amount of hydrogen we could try this. Unfortunately, with an efficiency of 40%, from the 6 TWh of summer surplus all we get back in the cold dark winter is only 2.4 TWh. Oh dear.

Molten salt:  “Molten salt storage is less efficient than battery storage—only about 70 percent of the energy used to heat up the salts becomes electricity again” but better than hydrogen as the 6 TWh summer energy will deliver 4.2 TWh in the cold of winter.

Batteries: These are up to 90% efficient so we will get back 5.4 TWh from the summer excess.  But at what cost, environmentally and financially?

The largest battery installations at present are 300 MWh for a sodium-salt battery in Japan and 129 MWh for a Lithium-ion battery in Australia.

Hornsdale battery, Australia

The Aussie one is the size of a “football field”; depending on the code, that is anywhere from 5000 to 7000 square metres. The Japanese one covers 14,000 square metres.  Both are used for short term load balancing and storage.

Buzen substation, Japan

Note that these figures are MWh and Minister Woods is talking about TWh.  MWh x 1,000 = GWh x 1,000 = TWh.  Current technology stores energy in the hundreds of MWh and Woods is suggesting a solution in the millions of MWh.

Now we are well into cloud-cuckoo land.

Using lithium batteries we would need 47,620 battery plants the size of the Tesla unit in Australia.  Just over 330 square kilometres of land for batteries. For comparison, that is approximately the area of the Egmont National Park.

Using sodium salt batteries the number of units drops to 20,000 and the area of land is a mere 280 square kilometres, approximately the size of Lake Wakatipu.

And while on the area required for storage, I am reliably informed that if the Ministers wanted to store 6TWh in a dam with a 102m drop to the turbine, and if the dam were 100m deep, its area would be 216,134 sq km or about 82% the area of NZ!  If the Greens didn’t object to that, I would! 216 square km, a bit larger than Lake Wanaka.  (My hydro engineer apologises for this slip of the powers of ten in his midnight calculations.)

The woman hasn’t got a clue and every time she defends her stupidity by saying, “The member needs to understand that actually leadership is required from a Government in order to send those long-term signals, and we are doing just that”, she looks more and more stupid.

The Minister tells us, “This government doesn’t lack political will”; but it surely lacks critical thinkers with a science or technology background.

I have an idea for the Minister:

How about we use our clean burning gas supplies and generate energy when we need it. We can even use the gas plants as standby instant load balancing facilities for your precious wind farms.

Just a thought.  You’re welcome.

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