A solar mega-project to supply the evening peak in UK and W Europe, would ideally be located at longitude 70-110⁰ W, so maybe in Florida, Texas, Cuba, Guatemala, Nicaragua or Peru. Certainly some geopolitics involved in setting that one up!

On the tidal lagoons, the proposed Swansea lagoon would generate 14 hours a day, but it was envisaged as part of a chain of at least six lagoons in Somerset, S & N Wales and Cumbria to give a continuous power supply as the tide moved up the Irish sea, with options for Kent and Lincolnshire. The total power from all the lagoons would be 3-5 GW (averaged over the cycle) which would be handy, but not on the same scale as offshore wind.

The Hendry review noted that lagoons can operate clever schemes with pumping between multiple compartments to give more continuous power, at the expense of less efficiency, so fewer MWh generated overall and less £ income. As the economics are very challenging anyway, the developers are not keen.

Lagoons are built in bays, so the habitat effects could be less severe than with dams built across estuaries, but would still be difficult to predict.

I'd been reading that too!
The emissions were overwhelmingly from Turkmenistan (who knew?) and Russia.
Followed by the US, Iran, Kazakhstan.

Rather surprisingly, the cost of fixing those leaks was estimated to be cheaper than the value of the methane saved, so not just "cost effective" but even "profitable"!

Posted By: WillInAberdeenAs the economics are very challenging anyway, the developers are not keen.

I think one of the biggest hindrances to these kinds of large scale infrastructure projects is the applied discount rate and term (i.e. delivery timescale). Often, this is calculated over just 25 years whereas we know these facilities generate review for much longer, as hydro projects have demonstrated and where this problem has historically been a factor. The need is to re-evaluate much of these to include longer and potentially multi-generational terms, which would dramatical help on the side of investment.

After a govt prints money rather than borrowing it/issuing bonds, why does it ever have to be 'paid off'?

Thanks Will - clarity is your thing.

Posted By: WillInAberdeen"I promise to pay the bearer on demand the sum of ... "

is really antique, from early medieval merchants' promisory notes which meant exactly that, and got reconciled pretty quickly, like end of the day, or on an annual date agreed by society, or at a once-a-generation Jubilee on which all debts were extinguished to re-set accumulated inequality of wealth and associated power.

Then, as usury was taboo to Christians, to finance their wars the princes of Europe forced Jewish goldsmiths, despite their own taboo, to write them interest-bearing promisory notes against the stock of customers' gold deposited with them, soon for multiple times the gold's value, which made nonsense of "I promise to pay the bearer on demand the sum of ... ". That's how Jews - farmers and craftsmen - were forced to learn to become Europe's bankers, as a royalty-enforced fraud and a religious outrage, needed, enriched, envied, resented, judged for violating their taboo and for the heartless avarice that usury creates, blamed, persecuted; accompanied by regular 'bank failures' when the promise couldn't be fufilled and/or by princes reneging on their debts.

It wasn't till early 20C that the theory of why this kinda worked became fully formed
https://core.ac.uk/download/pdf/6917403.pdf
enabling the fraud to be more glossed over than ever, but the usury taboo remains to this day, taken seriously only by Muslim banks which require convoluted rationalisations to function.

So "I promise to pay the bearer on demand the sum of ... " is a meaningless nostalgia today and only appears on banknotes, which make up only a few % of total money. Though it (debts must be honoured) holds good for individuals, corporations and banks, it need not apply when govts 'print money' (except as self-inflicted unnecessary free gift to the private sector), especially to govts that issue independent currencies, like dollar, euro, pound, yen, renmimbi (lesser govts' currencies are only rebranded dollars, euros (the EU member states) or soon renmimbi). It is very far from being the self-evident principle of Will's first two paras above.

2nd para should read
"Central banks creating money by computer keystrokes, helicoptering same into the community which buys stuff with it from same community, is a completed transaction, with no further obligations."
No debt is (or need be) promised or implied to anyone. It may be true that an excess of spending over tax receipts may accumulate but so what - it's just a number which in a way is a measure of historic healthy vitality in an economy, that it can sustain injections of 'tokens of liquidity' (money creation) with less need for 'putting the brakes on' (taxing money back out of the economy).

However, Will's central two paras, starting 'The ideal' and 'But if' are perfectly correct. Just as much skill and judgement as ever, pacing the money creation, targeting initial recipients of the created money without political favoritism, and ensuring the money stays liquid, not just siphoned into spiraling barely-liquid (tokens of power) stock market 'wealth', is needed, otherwise the classic danger of inflation will soon arise and wealth inequality will accelerate.

"Thomas acknowledged that concerns over possible damage to an internationally important marsh and mudflat habitat, harming wildlife had blighted previous schemes.
But Thomas said: “The changing landscape of the climate emergency, energy insecurity, rising costs, and rapid technological improvements, indicate that many of these policy, cost and environmental barriers may no longer be as significant.”

So this is of a piece with the (mainly Tory) gang who want CoP's green impetus watered down, in UK, first because of rising gas price, and now for energy independence from Russia etc. Estuarine ecological catastrophe? never mind.
"More than £25bn and 10 years or more to come to fruition" is perverse, when the path of least resistance is actually to just let rip the extraordinary impetus and quick results of renewables.

Yes, he's not coming from that Tory climate-denier pro-biz-as-usual fringe, but he's falling right into their reasonable-seeming honey-trap which is in fact incremental tactics towards an extreme-libertarian endpoint.

Far better that their
"Western Gateway “powerhouse”, a coalition of politicians, business and public sector leaders and academics covering an area stretching from Swansea to Swindon and straddling the Severn, designed to rival the Northern Powerhouse and Midlands Engine"
should wholeheartedly embrace environment, ecology, climate etc as both the end and the means to the prosperity they desire. How refreshing that would be! Instead of
"At its inaugural conference, delegates were told a Severn estuary tidal project could provide up to 7% of the UK’s energy needs"
- same old ...

Posted By: WillInAberdeenI don't think Jeremy Corbyn sees his support for tidal power as an "extreme libertarian endpoint"!

Probably not! The old left, from Lenin on, loves its heroic socialist-infrastructure fix-its just as much as Boris loves his ego-boosting ditto. The 'extreme libertarians' have no particular love of infrastructure, except as part of general scope for unfettered, untaxed money-making for their paymasters the rich and powerful. They want no restraints to that such as environmental/ecological/climate considerations, and adopt any available pose, such as false concern for citizens' cost-of-living, to 'temporarily' postpone 'green' policies. I'm saying that the traditional left (as is well rooted in Wales) easily allies itself with that same tactic, for its own quite different reasons, in this case adopting the available pose of energy independence, and hang the estuary's ecology.