Posts by John Robson 5225 publicly visible posts • joined 19 May 2008
"Except in rockets."
And even then it's a pain to use...
Hydrogen boils at about thirty kelvin below the temperature at which oxygen freezes - so you need vast (because low density) tanks, with substantial insulation even between the various cryogenic propellants (turbo pumps and injectors tend not to like processing solid oxygen).
For final stages the specific impulse (~460s, compared with ~370s for methane) can make a big difference though.
If SpaceX can get Starship and tankers working well... that would devalue (not eliminate) that ultimate efficiency advantage.
"I also wonder if we shall see battery pack swaps for trucks, where it doesn't seem to be popular for cars."
We already do see that, there is a company in Australia which is doing electric conversions with replaceable (with a forklift) packs. Which is great for "shuttle" style journeys, since you can leave a pack at each end charging slowly. It also means that they don't need to build whole trucks, there are lots of working chassis already out there.
"Also the pipework infrastructure is already there whereas the electricity grid simply won't cope with everyone going electric for everything."
Except that the pipework won't contain hydrogen (rather small molecules with a tendency to embrittle metals*), and you can't add an odourant as we do for methane (because the hydrogen will leak without the odourant leaking). You'd also need to run a very high flow rate.
And the grid will cope - it's not even particularly stressed at the moment.
A heat pump will output 3+kWh of heat for every 1kWh of electricity consumed... so you're hydrogen boiler had better be at least three times more efficient than using that hydrogen in a power station (which conveniently also eliminates the need for distributing the little buggers).
We have about 10TWh natural gas storage available - or ~1 trillion m^3
If you stored hydrogen in that instead, you'd get a third of the energy stored.
* Yes, I know copper is "less susceptible", but there is an awful lot of copper piping carrying gas in the country, it doesn't need to be very sensitive.
- 240 miles needs one break, but won't accept a vehicle that requires a break at the same time as the complainer's bladder.
- Must be able to do more than 7 hours (you shouldn't be driving for that long without a break anyway)
- Assumption that chargers at service stations are extortionate
Nearly a full Bingo card there... C- must try harder.
"I don’t know whether government statisticians know the proportion of houses that have a drive, and blocks of flats are an even bigger problem"
Well the RAC have some good published figures on this kind of thing:
- Average car is driven just 4% of the time (70%+ of the time they're parked "at home")
- Significant majority of households have, or could have, off street parking (75% in Wales, 68% in England, 63% in Scotland, 44% in London)
Consider that the figure likely correlates quite strongly with the 22% of households which don't have a car:
- through urban living with decent transport, e.g. London
- or through economic correlation, terraced houses usually cheaper than semi detached with off street parking
Blocks of flats often have car parks, so there is really no challenge there at all, you already have a car parking space, often a reserved one. The entire car park could, and should, be wired up for chargers at every spot. They're one of the easiest places to deal with.
"Again, not trying to say an EV is bad, just giving my tale with the data I collected to gauge if it would work for me."
That's a very odd test to see if it would work for you - do you spend lots of time at an unfinished customer site and a distant, and dishonest, hotel?
When you say a supercharger cost you $95 for 90%... that feels like you've fallen foul of overstay charges.
That doesn't *have* to be at home though - it can easily be an hour whilst you're shopping, then an hour or so when you're out for something else - let alone the potential for 8 hours if you have a place of work. It also doesn't need to be DC charging; an AC charger is a glorified light switch, which makes their installation, and therefore their energy, much cheaper.
Destination chargers, and that includes anywhere that has car parking, need to be utterly ubiquitous, and they will be...
Last year took a trip to London to visit the Natural History Museum - we used to drive to Cockfosters, but the tube is a pain in a wheelchair, so we drove all the way this time - pulled up just round the corner from the NHM, plugged in and then visited Hope, Dippy, and various other exhibits... Returned to the car which was heading towards being full again. The idea is to "ABC"... always be charging, just a trickle charge whenever possible is going to get you the miles you need.
An average car in the UK does about 20 miles each day - there will be some drivers who do substantially more, and the distribution won't be even so the relevant number for calculations will be lower, but 20 miles is about 5kWh each day, which is an hour of charging at a standard AC charger, two hours for a granny charger... it's really not a huge amount of charge to find.
They're basically all tap and go now - that technically being a mandated requirement on Rapids at least.
I use a combination of tapping a credit card and my octopus card.
Of course you can't use fuel cards at different groups either, so the situation isn't actually all that different.
It *was* a pain, but hasn't been for a number of years now.
The major exception... Telsa Superchargers, you don't do anything other than plug in, and the car and charger communicate and the billing is done automatically (which really ought to be the overall model).
With them opening up to other vehicles you would need the Telsa app to initiate the charge on those.
But I can't recall a rapid charger I've been to in the last several years that didn't accept contactless payment (though comms issues should be handled better).
In fact I can't recall a fast charger that didn't accept contactless either - though I can't recall (the last one I remember using was in Hull, and that was free, so...)
"non optimal"
110 miles a day from "non optimal"... that's the takeaway here. Even the slowest possible charger gets more miles over a normal day than you are ever likely to use.
I'd also not return to that hotel - getting one closer to the client, preferably much closer. But then I generally prefer to walk/wheel to work whenever possible...
I'd also be raising issues with the hotel... because that looks like deceptive advertising.
Yes - it worked.
A couple of extension cables isn't unreasonable.
Having to go to a smelly "special location" to put toxic fuel in a tank is a far less pleasant adjustment than plugging in a power cable.
Choosing to go to a park for a walk seems like a very nice way of passing time that would otherwise be sat in a hotel room staring at the wall.
Of course the fact that the hotel is aware that charging points are needed, and that the office is looking to install them seems to have completely passed you by.
> I guess I'm one of the vanishingly few to have an issue that's not for lack of trying?
From the voltage I guess you were in a different country, and from the anecdote you were renting on a trip, which is an interesting use case, but one that should be trivial to cover - as you pointed out there were two places that could/should have had destination chargers available...
But also - you made it work without much difficulty...
Even a 110V circuit gives ~ 2kW (1.8-2.4kW for 15-20A) which is about 6 miles/hour, so easily 60 miles overnight, or 50 for a working day.
That's 110 miles a day added on the very slowest of connections - even with a pretty excessive 45 miles round trip (feels like bad planning) that's 65 miles added per day without you ever having to visit anywhere special.
Would L2 chargers have been better - yes, if either location had what is basically a glorified light switch on a decent circuit then you'd not even have had to think about charging - just plug in overnight, or whilst working.
a) What uncertainties? There is no uncertainty any more, there is just a deliberate lack of research, or a lack of up to date research.
b) Not an option - that's the point.
c) Great, I don't suggest that BEVs are the be all and end all - public transport needs a huge amount of investment, and to be run as a public service, not as a profit centre.
EVs *are* the easy option, unsurprisingly the used market isn't mature yet.
a) What issue - the "I can't drive a million miles before breakfast" brigade are just one group that won't listen.
b) The point is that if the issues disappear with experience... because the issues aren't.
"The main use for services is usually for a toilet break, and stretch your legs a bit, not to fuel up."
Only because service station fuel is generally expensive... with an EV many more people will be using the motorway chargers on their journeys at the start/end of each major holiday.
We do need a good array of chargers at each service station, but that's a long way from "every space".
I'd like to see SMR or micro reactors located at service stations - with 10-20MW generation at each of the ~100 service stations that's a couple of GW for the grid when the chargers aren't in use, and therefore a 20MW grid connection available, so a max draw of 40MW, which would be a very substantial number of rapid chargers.
People don't like change... that's always been the case, and petrol took a while to take over from horses.
We're in a position now where we don't have the time to take a generation or two to transition away from ICE vehicle (to whatever).
The "issues" which are raised are always raised by people who haven't driven an EV, not by those who have.
"It's a valid defence when the government is trying to force mainstream EV adoption now. There's no way, not with current levels of investment in power generation and charging infrastructure, that this country will be ready for hybrid-only new cars from 2030 and zero-emission only new cars from 2035."
So from a legislative perspective... in 2045 ish there will be few ICE vehicles on the road...
"During the first half of 2022 an average of 891 charging devices were installed each month. Fast-forward to the beginning half of 2023 and the UK is now seeing an average of 1,622 charging devices installed per month."
In terms of power generation... assuming all miles are driven at 3m/kWh then we don't need any more electricity generation than we had earlier this century.
The reasons for mandating V2H are nothing to do with "oh the grid can't cope" and everything to do with allowing people to use their assets more than 5% of the time, and yes - to act as a decent grid stabilisation option.
There are vanishingly few people for whom an EV isn't already suitable - I can't think of any actual examples in fact (ignoring such complaints as "must to a million miles to a ten second charge before I'll consider it" and "but it's got no clutch").
"A gas-guzzling supercar isn't economic, but you can floor the gas pedal without immediately checking how many minutes you have left."
Clearly never driven one hard... The Veyron famously had a 12 minute tank IIRC? (obviously rather difficult to find a location where you can burn through the fuel that fast).
An EV does lose more range when used at high power... but not nearly as much as you might expect - you really lose range by braking hard (and the two tend to go hand in hand). Accelerating onto a motorway, or as part of an overtake, makes substantially less difference than you might expect.
"I'd be happy to switch to electric when they can do 300km on a single charge and get an 80% charge in 10-15 minutes."
Well both of those are already possible... but neither are really necessary for the *vast* majority of users...
300km is 185 miles, so at least 2.5 hours - which is definitely comfort break territory, and that usually takes quite a few minutes.
80% charge would be 150 miles range (still over 2 hours), and at a reasonable 3.5-4m/kWh is ~40kWh... for that to take 12 minutes is a "mere" 200kW (CCS already supports 350kW).
Even the MG4 does 450km, and 135kW charging - not quite the 12 minutes you're looking for, but also 50% more range.
You seem to be under the impression that reducing the peak demand on the grid somehow makes electricity more expensive for everyone else - that's not the case, in fact by reducing that peak load the cost of electricity is reduced because the most expensive generators are taken offline.
We still pay the standing charge, even on days when we draw no power from the grid (just using it as a 50Hz generator) - if we went completely off grid then I'd agree with you - we'd be loading the remainder of the grid users with higher costs, but no-one does that if they have the choice.
But yes - Vimes Boots applies, you need to be able to afford the kit to reap the benefit. With interest rates at very low levels (like they have been for most of the last several years) it made sense to take advantage of that opportunity, and with price volatility over the last year or so, and likely to continue, it has made a lot of sense.
Mine has been up for 250 days, and has generated 1370kWh, of which we've exported 214kWh
That scales to an expected 1900kWh for this year (using a linear regression to fit to the irradiance data from visual crossing, and applying that to the past 365 days) from a 2.4kWp system.
The 9.5kWh battery does very well - charging overnight on cheap power during the winter, and doing some of that in the summer (dependant on expected load and weather).
An ASHP is on the cards - ran the boiler at a 45 degree flow rate all through last winter, but I reckon that boiler has another year in it yet... (fingers crossed)
"Any annual number is an average"
Technically it's a total :p
But of course it's biased towards the summer, the point is that there is a *huge* amount of energy available, and it does make sense to use that resource.
"doesn't help ... with no storage"
Which is why storage is important, and noone is claiming otherwise - the question is how much short, medium and long term storage is appropriate - and what we're going to use as alternative generation on the very rare occasion that the storage is emptied (because yes, we need a considerable amount of storage and interconnection with other grids).
Steam bypass is great when you're reacting by slowing down, less useful when you need to increase output - if instead you combine with storage then you don't need to react quickly and effectively curtail your nuclear production... The storage is then dealing the variability in demand, rather than the traditional view of it dealing with variability of supply.
It's also not really an issue until you have effectively zero rapid response plants (peakers or general gas) - even if you had 80% nuclear, so long as your demand is reliably above that level... it's not an issue.
the 2/3rds figure doesn't rely on some heavy averaging - it is an aggregate figure demonstrating that the available energy from distributed solar is more than a token effort. I made no claim that the generation and demand were synchronised, nor that sufficient storage was available.
Lithium (and Sodium) batteries are a short term (~daily) storage, and give very rapid response times to keep the grid balanced. Flow batteries have the capacity for long duration operation with low storage costs, I don't know where Iron Air batteries sit in the scheme of things.
Pumped Hydro is slower, but more long term (weekly to potentially seasonal) storage - but it does have disadvantages in terms of space and specific geographical requirements.
There are other technologies around - indeed this is one of the potentially viable use cases for synthetic fuels like green hydrogen or air to hydrocarbon conversions, but there are also high temperature thermal stores being tested and I'm sure other technologies I'm not familiar with.
Dunkelflaute do happen, but in northern Europe they rarely last more than 24 hours (Li et al 2021) - with ~50-100 hours in the months of November through January - and more importantly the correlation between countries is relatively low (see fig 7 in Li's paper), meaning that connections between the grids in Europe go a long way to reducing the frequency and duration of these events.
But let's assume for a moment that we have no storage that lasts more than a couple of hours... that means that for 5-10% of the year we need to have additional generation - so for 90-95% of the year we get very cheap generation, and then we pay a little more during those short periods - don't let the "but sometimes" prevent taking up the solution that works the vast majority of the time, and provides a much lower overall cost even when the expensive periods are factored in.
Nuclear generally has the issue that it is relatively slow to react to demand changes, though modular reactors can, and should, be faster. They'll still need substantial storage systems though. Unfortunately the regulatory environment for nuclear power is hindered by the weapons potential of said facilities - and that is just one reason that wind and solar are substantially cheaper than nuclear power. I'm sure that with development of modular reactors the cost will drop, but the cost of wind and solar is nearly an order of magnitude below that of nuclear (Lazard, Oct 2020) so there is long way to go.
There is a good chance that some of the deep drilling geothermal research could yield a further source of reliable power which whilst not strictly renewable is sufficiently abundant that it may as well be.
The advent of many more connected storage device (whether thermal or electrical storage) also means that we can shape demand, and we can do to an extent that was unthinkable only a decade or so ago.
Is there a "single solution to all the problems"? No - but there are solutions, which when brought together can wean us off fossil fuels, and can do so with today's technology.
One important part of the solution that we shouldn't forget is that we should also be scaling down the amount of energy we use... that's going to be partly through efficiency gains (e.g. heat pumps rather than boilers, EVs rather than ICE vehicles), but partly through actually reducing the amount of energy (e.g. better insulated homes, reduced driving miles).
tl;dr:
Is nuclear part of the solution? Yes - it probably is. It's also got some really nice characteristics that fit in well with some of the newer demands being placed on the grid.
Is it the whole solution? No - because there is no "one" solution.
Whilst it is less efficient in some ways - in others it's great - the power from my panels doesn't need transmission for instance.
The array also takes exactly zero space, because my roof was already there...
And because it has a direct impact on the owner's pocket, there is a strong incentive to keep it clean.
In the UK irradiance is about 750-1100 kWh/year/m^2. Call it 900 and then assume 20% panel efficiency - that's 180kWh/year/m^2
England is ~13M hectares, 1.3% of which is residential buildings
That's ~1.7 billion square metres of roof, let's assume that ~30% of that could be used for panels - 500 million sqm of land area.
That's 180 kWh/sqm * 500 M sqm = 90 TWh per year from residential buildings alone
Another 1.4% of the land is other buildings - which would be another 100TWh.
That's 2/3rds of the annual UK (not just England) electricity demand - from just 30% of our collective roof space.
"The real solution for a high-energy Britain is nuclear power, lots of, and an adequate distribution grid."
The Real Solution (TM) is a mixed grid - with lots of renewables, various storage technologies and, yes, probably a good slug of nuclear in there as well.
It is vanishingly rare that any Real Solution (TM) to a real world problem is one specific technology.
We need to move towards modular reactors though - whether those be the four acre SMR or the container sized micro reactors.
The age of the one off custom design plant needs to come to an end.
"I can only think that a meaningful use case is to supplant fixed (fibre) broadband to premises (FTTP)."
You'll never supplant fibre with a shared medium resource.
There are a small handful of cases where premises are sufficiently distant that it might be a reasonable option, but that runs completely counter to the probable coverage of the base stations.
In those cases Starlink already provides a decent (but still well behind fibre) connection...
Smaller cells can already be achieved by simply lowering the power of the transmitters, so you could pack an urban area with more cells if you were so inclined.
Autonomous vehicles is an appalling use case - you want vehicles to be as self contained as possible, though a rapidly negotiated local network could be useful - I'm approaching this junction, and can talk to the few dozen cars within 400 yards to share plans.
In my experience slack has been far better than Teams.
Calls (Huddles) work fine - and it's usefully integrated into various ticketing systems etc that make my life easier.
Probably helps that this machine isn't running an OS by a company that wants to kill slack and force everyone to teams... or am I being a touch too cynical?
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
