Tides rise and fall, and can be used to produce electricity. If that electricity is sufficient to pay for the cost of developing and maintaining the equipment to produce the electricity, then what has been created is a free energy machine.

Similar with solar power, wind generators etc.

I wonder why the author didn't think of this.

Almost all patents are developed by men, and there is a definite difference between men and women regards inventing and building things.

I wonder why the author didn't think of this.

The article reminds me not to vote for the Green party in the next few elections at least.

Cheryl, I see you've gone all quiet. Did you have a look at those reports or are Goldman Sachs and the ABS too "asinine and unsubstantiated" for you?

It's hurtful when one's assumptions are challenged, isn't it? Even more hurtful when the challenge is based on hard numbers. I can understand why you'd not want to believe the figures, but unless you can come up with something better, I'm afraid they have to stand.

Do try to make sure that whatever you come up with isn't "asinine and unsubstantiated" won't you?

Vanna, tides aren't really very good for power generation, unless they can be buffered in some form of dam. They simply don't have a lot of energy, mostly because they don't rise very fast in most cases. There was a proposal I was actually involved with at the preliminary investigation stage to dam the Exmouth estuary and make a hydro power facility. Exmouth is good because the tide has a range of almost 5 metres, but the proposal fell apart on both environmental grounds and on simple costs. It takes a lot of money to build 30km of dam in alluvium.

Another possible method is to use floats that are driven by tides, but 1 cubic metre of flotation only produces about 1kW per tide in the sorts of tides that we see in SE Australia and the mechanical aspects of capturing that are complex to say the least. The same problem applies to other mechanical methods, such as vanes or impellers.

It's a nice idea, but the energetics don't stack up.

An excellent article grounded in reason--no wonder it has no impact on most of the cohort above.
The old alchemist was indeed motivated by praiseworthy ambitions, but sadly the modern alchemist is an economist, who's insane logic is that the market can cure all ills. The entrepreneur is the amateur alchemist and puts his faith in the economist that the perpetual motion system has indeed been discovered; it's incongruously called the free market. Not only are these modern alchemists able to place absolute faith in the mystical properties of the market, but their able to dismiss with the same breathtaking surmise, irrefutable empirical evidence, as well as their own god-given powers of induction. To wit: "none of the 'silver bullet men' are anywhere near as deluded as those who believe that 'our planetary civilisation is being confronted by a dizzying array of chronic problems – from climate change, to desertification, to ocean acidification'". It's all a conspiracy Jon J, right?
What the author doesn't say explicitly is that the capitalist system has evolved to exploit gendered propensities; it doesn't cater to human needs, it cultivates them, ad nauseam.
As I've said elsewhere, economic growth in a closed system is as subject to entropy as energy is, it's as unequivocal as the second law of thermodynamics--though the minimifidianist is capable of denying anything.
Technology won't solve the problems the free market creates; like any household budget, we have to live within our means. Far from having found the secret to eternal life, we profligately live for the moment.

squeers:"we profligately live for the moment"

The moment is all there is. Any experience is just the sum of the moments that composed it. The trick is to make each moment count as best you can in whatever way you choose to do the measuring.

The great achievers manage to get more out of their moments because they can string them together with more purpose than most bother with. It doesn't really matter if their purpose was "useful" or not - the moments still passed. If they caused someone else to invest their own moments with more purpose, then in such small ways is human life made more tolerable.

Antiseptic,
a philosophy of living in the moment is all well and good, and it's true that he who throws away the present moment throws away all he has. But it's a philosophy "founded" on material security rather than preceding it. Life is precarious and uncertain ultimately, but we do not occupy geological time and in terms of all of human history (the blink of an eye) there has been a mostly prosaic continuity in terms of natural conditions, while we've adapted slowly to regional differences. To apply what amounts to an individualistic and existential philosophy to the rapacious impacts we are having as a species on this ancient biosphere, with no regard for tomorrow, notwithstanding the overwhelming likelihood that the planet would maintain the current equilibrium for millennia if we treated it with respect, shows and utter want of philosophy ("how should we live?") and contempt for all ethical considerations that might have made humanity worth preserving.

squeers:"it's a philosophy "founded" on material security"

Not at all. If one is not materially secure there is even more reason to give primacy to the present. The past is gone and the future unknown. the only way to ensure there is a future at all is to make one's moments count.

I think you should re-read my post above, old boy. You seem to have worked yourself into rather a lather over something quite invisible to me.