* Posts by John Robson

5142 publicly visible posts • joined 19 May 2008

The choice: Pay BT megabucks, or do something a bit illegal. OK, that’s no choice

John Robson Silver badge

Re: Dodgy cabling

Yes - undoubtedly the reason... it's still a surprise to me that it worked.

The sheer distances involved and the fact that none of it was anywhere near spec... And of course the fact that one end was a hub, not a switch - with likely reflections from the dodgy (and that's generous) connections... There were a bundle of those cables with ever increasing distances (as they left the bundle to go to each switch).

Not even sure it was cat3 to be honest... it was clearly intended as telephone cable.

John Robson Silver badge

Re: Dodgy cabling

Mine was in a hall of residence, connecting a 24 port 10Mb hub on each staircase to a 10port 10Mb switch with two additional 100Mbit ports

Distance was *well* over 100m, and it was Cat3 (IIRC) cable with the "patch bay" being telephone oriented, so the two needed pairs soldered onto about an inch long which slotted into spring contacts.

Grounding the rest of the wires in the cable gave us reliable connections (somehow)

Thames Water to datacenters: Cut water use or we will

John Robson Silver badge

Re: someone please explain

"That said, there's a *lot* TW could do, but it requires investment, which, notably as per recent news reports, they can't really make because they can barely afford their debt payments."

You misspelt dividend payments.

John Robson Silver badge

It comes in as drinking water and leaves as foul waste.

Musk's X tries to win advertisers back with discounts

John Robson Silver badge

Re: Define Extortion

No - it means that the account has paid $n

It doesn't mean they've verified anything, certainly not each post made.

NASA awards $150 million to prototype tech for humans on the Moon, and above it

John Robson Silver badge

Re: Politics

Also the FH isn't man rated as far as I know - but lobbing an unoccupied dragon doesn't need it to be.

If the lunar starship can manage enough fuel to return to an LEO then the alternative journey is very attractive indeed.

LEO to moon requires 5670m/s (https://i.imgur.com/AAGJvD1.png)

A return trip would take the same (assuming the lunar starship can't aerobrake)

Lunar starship apparently has about ~9km/s available: Plenty to get to the moon and then get back to a 100km orbit (another 1730) with a healthy safety margin - lifting an additional few hundred tons of propellant is quite costly though.

John Robson Silver badge

"Good news! There is a spare Orion capsule on Earth. Skilled selection of requirements means that the only thing that can get an Orion capsule to you is... SLS. Another one can be assembled, tested and launched in just two years!"

If I am correct then there is an alternative solution... both dragon and orion use the NDS docking port, so you could simply lob a dragon over to the NRHO for transfers.

The dragon was originally designed to deal with the heat loadings of a return from lunar distances (I don't know if the heatshield has been derated from that original intent), and it certainly has the space and life support for a trip back.

BT and OneWeb deliver internet to rock in Bristol Channel – population 28

John Robson Silver badge

Re: Not really plug'n'play is it?

On the basis that my parents managed to get starlink installed and running inside half an hour - I have to agree with you in terms of simplicity of setup.

John Robson Silver badge

Yes you can call 6 a block...

Do you actually need public IPv4 addresses directly, or can you run a VPS for those public facing things (potentially with a proxy or a port forward over a VPN if you need the server itself to be at home).

John Robson Silver badge

Connection reliability is pretty good.

What's the specific issue with the NAT?

Bosch goes all-in on hydrogen with €2.5B investment by 2026

John Robson Silver badge

Re: Not about efficiency

The working fluid of a vehicle is important - nothing to do with CO2, it's important because of the localised air quality where people drive.

If you don't need a working fluid then all the better

John Robson Silver badge
Boffin

Re: Again?

Have you come up with a way of burning fuel twice then?

Or are you just ignoring the fact that batteries will provide several orders of magnitude more energy on demand across their lifespan, and can then be recycled into new batteries.

John Robson Silver badge

Re: I was expecting

"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.

John Robson Silver badge

Re: Again?

"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.

John Robson Silver badge

Re: Maybe the wrong target

It has a tendency to escape the atmosphere.

John Robson Silver badge

Re: Is hydrogen ‘green’?

The oxygen is needed when the fuel is used, so we won't end up with an oxygen rich atmosphere.

John Robson Silver badge

Re: Again?

"If you need to travel far, then there is basically no way around fuel cells."

If you need to travel far then there is no beating an electric train.

John Robson Silver badge

Re: I was expecting

"Most" isn't good enough - and if you look in buildings there is a massive amount of copper pipework, much of it very difficult to replace.

John Robson Silver badge

Re: I was expecting

"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.

Framework starts taking orders for 16-inch repairable, upgradeable laptop

John Robson Silver badge

Re: Expensive, but Worth the Money

Meh - not horribly expensive.

Can get slightly older hardware for under £500 as a complete, low power, home server.

If you've got some memory and storage on a shelf then you can get that down to ~£350 with a couple of usbc adaptors (hdmi and ethernet being my preference).

It might be nice to have some cheaper options available as student laptops, with the upgrade/repairability as a major selling point.

Linux lover consumed a quarter of the network

John Robson Silver badge

Re: Rule one...

Depends if you define the driver as content...

It's not that often that non live contents exceed the value of the vehicle.

John Robson Silver badge

Re: Rule one...

Many years ago I grabbed a server from the office to take for EMC testing in a small wooden shed in the middle of a field...

The tests were booked for the next day, so I took the server home overnight, and then to the EMC testing facility in the morning. I spent some of the journey home doing some basic calculations:

24 disks, 1TB per disk (biggest available at the time, must have been 2007/2008), 70 minute journey time.... that's a little shy of 50 gbps

I mean the latency sucked (two days to get data back to the office), but the bandwidth was quite substabital.

The other amusing calculation was how much more valuable the server was than the vehicle it was riding in...

Rocket Lab wants to dry off and reuse Electron booster recovered from the ocean

John Robson Silver badge

It looks almost identical to a single stage to orbit vehicle - that is it looks generally rubbish.

Dropping ~100 tons (Falcon 9) of engines/tanks makes a *huge* difference to the performance of the upper stage.

John Robson Silver badge

Re: Probably just as well

They do glide, but the glide angle is rather steep.

You want to add wings, and enough structure to maintain the integrity of the vehicle in a transverse direction to the loadings actually required for flight, and landing gear, brakes and who knows what else that I haven't thought of in ten seconds...

Have you calculated the likely mass required there and compared that with the relatively small propellant mass needed?

John Robson Silver badge

Re: Probably just as well

The landing upright "trick" also means that you don't need a secondary set of engines, or a structure designed to take static and shock loadings across the vehicle.

It's not nearly as dumb idea as you might imagine.

John Robson Silver badge

Re: Probably just as well

Marine systems (barges, tugs etc) are famously expensive, and catching things with a chopper has quite a long history in spaceflight.

It's not unreasonably to try and avoid having clean out the saltwater, which is generally not good for things.

AWS and Azure own lion's share of $120B cloud infrastructure market

John Robson Silver badge

Re: Rob Peter to pay Paul

Yep - and for many workloads it makes sense, the economies of scale that the hyper scalers get aren't all passed on, but some are.

Lamborghini's last remaining pure gas guzzlers are all spoken for

John Robson Silver badge

That's *much* more reasonable.

John Robson Silver badge

Re: EV - Not Yet...

- 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.

John Robson Silver badge

You are likely to find that the up and down mountain passes gets you better milage than motorway driving.

Aero losses are the real killer, and BEVs don't just throw away energy as heat when going down, they recover much of it (not all, but infinitely more than an ICE can manage).

John Robson Silver badge

"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.

John Robson Silver badge

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.

John Robson Silver badge

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...)

John Robson Silver badge

"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.

John Robson Silver badge

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.

Tesla plots entry to Britain's stagnant energy market

John Robson Silver badge

Re: I'd give it a chance...

Yes, Tesla have pulled out of that agreement... which is a bit of a pain because it's actually quite hard to get the battery to do what the user wants - it's far too insistent on doing it's own thing.

John Robson Silver badge

Re: Reminds me of China

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.

John Robson Silver badge

Re: Reminds me of China

You might not, but the driver isn't always financial.

A constant heat is far nicer to live with, and reducing energy usage is important.

John Robson Silver badge

Re: Reminds me of China

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)

John Robson Silver badge

Re: Reminds me of China

"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.

John Robson Silver badge

Re: Reminds me of China

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.

John Robson Silver badge

Re: Reminds me of China

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

UK Land use:

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.

John Robson Silver badge

Re: Reminds me of China

As and when gas is pushed off the generation scheme entirely... the price will drop.

John Robson Silver badge

Re: Reminds me of China

"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.

John Robson Silver badge

Re: I'd give it a chance...

Worth calling them - they're usually pretty good about allowing switches (just not rapid switches, so you can't flip flop between flux and go based on the weather for example, but you can switch based on the season)

John Robson Silver badge

Re: I'd give it a chance...

Octopus Flux is still available...

https://octopus.energy/smart/flux/

Works with any solar/battery scheme (and in many respects devalues the battery)

China succeeds where Elon Musk has failed with first methalox rocket

John Robson Silver badge

Re: Interesting but not earth shattering

The story that follows (go and buy the book people) is also very well told.

Clingy Virgin Media won't let us leave, customers complain

John Robson Silver badge

Re: Simple approach

And of course recall all the DD since the first request to cancel.

InfluxData apologizes for deleting cloud regions without performing 'scream test'

John Robson Silver badge

It seems like a mistake they won't want to repeat

...

Though better still to learn from the mistakes of others.

Starlink satellites leak astronomy-disturbing EM radiation, say boffins

John Robson Silver badge

And yet apparently not - because fibre isn't being laid.