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A PHYSICIST WRITES . . .
(March 2018)
Writing this column often seems to be a process of never quite catching up (like my life in general!). When I aim to bring topics up to date, as I did last month, invariably more news of at least one of them will emerge within a few weeks, and I shall feel the urge to pass it on. A case in point is the National Grid, which (I said) has only limited storage capacity for helping it to balance supply and demand, when these are changing unpredictably and rapidly – think for example of wind farms and solar panels (unpredictable supplies), and electric vehicles being plugged in for charging (sudden demands).
Certainly the two new ways of storing grid-energy that I described last year (as you may recall), namely large flywheels and big lithium-ion batteries, are still only making a tiny contribution (if any). The most practical means of storage is – and always has been – pumping water uphill into reservoirs, from where it drives a turbine-generator as it comes down again, when needed: what’s happening is that the electricity is being converted into gravitational potential energy, and then back. But this brings us to the latest idea that I’ve seen on electricity storage, one so simple that I should have thought of it myself!
A large number of disused mineshafts are dotted around the country, and each one offers the, er, potential for storing potential energy, but much more compactly than the reservoirs do (also, there aren’t that many elevated locations suitable for reservoirs!). The proposal that I read about last month was to adapt such shafts, and also sink new ones, so that weights of up to 3000 tonnes can be lowered down them to generate electricity, and hauled up again to store it.
The stored energy won’t gradually leak away (unlike that in a flywheel). The system can be expected to last for more than 50 years without any loss of storage capacity (which is doubly unlike a lithium-ion battery). And if the space above the weight was made airtight so that the air in it compressed as the weight rose, then the capacity could be trebled or more. The name of the company intending to make this superb idea work is Gravitricity: you saw it here first (probably)...
By the way, if you want to get an impression of the complexity of balancing our electricity supply, take a look at www.gridwatch.templar.co.uk, where you will see displayed (a) the almost-up-to-the-minute power consumption in the UK, (b) how much each different energy source (coal, gas, nuclear etc) is supplying to satisfy it, and (c) how all these figures have varied over the past day, week, month and year.
In January I tried to bring you generally up to speed on ‘autos’ (my name for driverless cars): I explained that although the technology is steadily advancing, it’s impossible to say when autos will become a familiar sight on our roads, because of all the other considerations – legal aspects, infrastructure and public approval. I’ve since seen two interesting predictions, however. One was that the most hazardous time for an auto will be if it suddenly requires the driver-occupant to take over control.
Tests in a simulator and in an actual auto have revealed that although the ‘sleeper’ could wake up, so to speak, and be in charge (of the manual controls) in a couple of seconds, it would probably take a further 50 seconds for him or her to apply full concentration. But suppose that several autos are moving together at speed on a main road, and their systems decided simultaneously that negotiating the traffic was beyond their capability: it’s alarming to think of them all being inexpertly driven for nearly a minute. The only recommendation in the report was to program autos to slow down before handing over control. Or better still, I think, to stop!
The other prediction was that when, eventually, all vehicles are self-driving the flow of traffic will be much more efficient than it is now, and so commuting (by road) will be faster. Hence the incentive and attraction of living further out of town will increase, and this will generate huge suburban sprawls of housing – of which we have quite enough already, not to mention wide roads and motorways. The Green Belt (which in England and Wales really means 15 individual green-belt areas) was set up originally to block urban expansion, but it will simply be leap-frogged, where it hasn’t been already, as commuting across it becomes fast and easy.
The Oxford University man who published this gloomy outlook advocated tighter restrictions to protect the countryside, as well as engineering solutions such as lowering main roads into tunnels, which “won’t be cheap, but becomes easier when human drivers are taken out of the equation.” What he meant by this was that autos would cope better (on their own) with the disruption from the construction, and then afterwards with the tunnels themselves. My guess, though, is that drivers will be needed for autos for a long time yet...
Finally, forgive me for finding fault with smartphones again, but whoever had the idea of incorporating a camera in them? And then who started the craze for using them to take selfies? Because the news this month (though it must have been a worry for much longer) was that people so dislike the size of their nose in a selfie that they’ve been asking plastic surgeons to give them a nasal reduction.
What they haven’t understood is simple perspective: the closer you are to a face (or anything that’s three-dimensional), the wider the nearest part of it will appear, in comparison to the rest. Viewed from several feet away, almost any face looks ‘normal’. Hold the camera closer in, at arm’s-length or less, and inevitably the question will be: “Does my nose look big in this?”. But it has taken the efforts of a research team at Rutgers New Jersey Medical School to work out and publish the simple geometry required to quantify the answer, which turns out to be: “Yes, about 30% wider than it should do.”
It isn’t clear, from the reports I’ve seen, if the surgeons have been encouraging or discouraging the worried nose-owners in their desire for treatment – the situation must present quite an ethical dilemma. And there’s another aspect which doesn’t seem to have been discussed at all (not this month anyway): a near viewpoint expands the nose but flattens the ears! When the smartphone-narcissists finally get the message and start asking others to take photos of them from a sensible distance, I fear they will be returning to the plastic surgeon and asking for a pinning-back operation instead.
Peter Soul
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