* Posts by John Robson

5142 publicly visible posts • joined 19 May 2008

Third time is almost the charm for SpaceX's Starship

John Robson Silver badge

~160 seconds to do all but a few tens of tons of propellant...

If that's ~65 tons burnt then it's 32TJ, or 200GW, *way* more than the UK grid ever pulls....

Those raptors are seriously powerful ~ 650kg/s mass flow, of which ~140kg/s is Methane, so that's ~7GW each... two and half times the largest power station in the UK (https://electricityproduction.uk/plant/)

And there are 33 of them... which would add up 231 GW - so that matches the initial estimate closely enough.

John Robson Silver badge

Re: ablative surfaces

From: https://www.nasa.gov/humans-in-space/after-15-years-1000-tests-orions-heat-shield-ready-to-take-the-heat/

"The Apollo crew module’s heat shield relied on a material called Avcoat to beat the heat. It’s an ablator, meaning it burns off in a controlled fashion during re-entry, transferring heat away from the spacecraft. "

"Following the Artemis I mission, the Ames team will also harvest samples of the charred Avcoat tiles to analyze how the material ablated."

Ablated - i.e. shed bits to carry away some of the energy of reentry

The shuttle however had a Thermal Protection System, consisting of High/Low Temperature Reusable Surface Insulation tiles - note the lack of the word ablative, because it wasn't an ablative system.

Space Explored has a useful paragraph:

"An ablative heat shield, as SpaceX uses on Dragon’s primary heat shield, works by heating part of the material itself into gas and burning away, thus moving the heat buildup away from the capsule. By comparison, a thermal soak heat shield – as was used on the Space Shuttle – is designed to absorb the heat and radiate it, without the material burning away."

Let's ignore active cooling etc, since AFAIK noone uses it yet.

John Robson Silver badge

It only needs to be strong enough to do it's job - it's not a structural element when it's open, and strengthening it would add mass that isn't needed.

John Robson Silver badge

Fuel efficient?

AtlasV takes 305 tons of propellant (first and second stage, no boosters) for a 12 tons to LEO

Soyuz takes 4*40+96+22 = ~280 tons of propellant for ~7 tons to LEO

Falcon9 takes 400 + 92 tons for ~22 tons to LEO, or 18.5 tons when the booster is recovered.

Those are mass factors of 25, 40, and 22 (26 with recovery).

Starship is 3400t+1200t, with a payload capacity of 150t (250t if expended)

That's a ratio of 18.5 (better than any of the above) when expended, and 31 when fully reused (middle of the pack, but without disposing of all the engineering every time).

John Robson Silver badge

"They are an inefficient, ineffectual waste of funds that should have been put into building out nuclear AND they kill birds."

Fewer birds than other buildings.

They are very efficient, and a very effective energy generation mechanism - forty something percent of UK electrical generation last year.

John Robson Silver badge

Re: ablative surfaces

Yeah - that's not the appropriate definition of ablative, that's a grammatical case.

Albative refers to "by ablation" which literally means "carried away" (Latin ablat-)

John Robson Silver badge

Re: Capabilities.

Launch a nice large, light, station element, filled with a bunch of satellites that need a similar orbit ;)

John Robson Silver badge

Re: Capabilities.

"Or maybe they'll have fairings that can jetison and still protect the re-entry vehicle."

Not an option - the fins* and header tanks need that fairing to still be there.

They'll end up with a massive door, or a pair, and that's not an impossible task - the shuttle had such bay doors.

* I like Tim Dodd's use of the term elonerons, cf_ ailerons

John Robson Silver badge

Oh - and they demonstrated cryogenic propellant transfer.

John Robson Silver badge

Re: ablative surfaces

Ablative tiles shed their surface through melting or evaporation.

John Robson Silver badge

Got to get SLS and Orion ready as well.

The starship bit is actually progressing fairly well, even if a little slower than some might have hoped.

They've demonstrated launch and hot staging of the full stack, along with reuse of the launch facilities.

They've demonstrated the flip and boostback burn as well as aerodynamic control of the booster.

They've demonstrated a full burn of the ship, and some degree of control on reentry.

They've also demonstrated subsonic control, flip, relight and landing of the ship (though not yesterday).

That's a pretty long list of successful operations so far.

The payload doors looked like they had some movement, but it's not clear how successful that was yet.

John Robson Silver badge

Exactly zero tons of kerosene... I don't think that they are still using generators.

Booster takes 750t of methane, Ship takes about a third of that (250t) so overall a thousand tons.

Methane has an energy density of ~50MJ/kg, so a launch uses ~50TJ of energy, that's ~14GWh.

Not a huge amount of energy in the grand scheme of things, the US consumes ~4EWh of electricity each year, and plenty of gas usage that isn't electrical.

John Robson Silver badge

Re: I nearly missed this!

The aim is for another half dozen flights - and they have the hardware to be able to do that.

Whether they can get the launch licenses through in time... the anomaly reports should be much simpler each time, but that's clearly a stretch goal.

John Robson Silver badge

Re: maximising

So you'll be calling for banning all cars.

Clearly "maximising public safety" is one of a number of things they are trying to optimise, they evacuated a very large area of the indian ocean, and the gulf of mexico of all air and sea traffic, and a significant area around the launch site of all people.

UK minister tells telcos to share telegraph poles if they can't lay cable underground

John Robson Silver badge

You need an inside man, and then put your wifi router *in* the exchange...

John Robson Silver badge

I used to get the same (80/20) on DSL.

Fixed price for life isn't a fair comparison, but I agree - while you've got it, keep it.

What's your current provider's current rate for an 80/20 connection?

John Robson Silver badge

"The cheapest package is more expensive and slower than my current ADSL.

So screw that. What's the point ?"

Really?

How fast is your ADSL?

Ok - wow BT now do a ridiculously slow "full fibre essential", which is £29 for 36Mbps....

Why? £30 gets you 150Mbps, £33 is 300Mbps. And they still don't do anything symmetric.

Whereas alternative providers do £28 for 150Mbps symmetric, £32 for 500Mbps

Latency is usually far better on fibre, as is connection reliability. No significant affects of rain or wind.

Caffeine makes fuel cells more efficient, cuts cost of energy storage

John Robson Silver badge

Re: Flow batteries

True - those would be applications with room for a couple of Really Big Tanks (TM)

(I mis-parsed the line about trucks in the original post)

John Robson Silver badge

Re: Caffeine or no caffeine

"Can you explain how completely wreck ecosystems by building a barrage across the Seven is different to completely wreck ecosystems with climate change?"

Certainly - the destruction would be localised and clearly attributable to a single project. It would also be substantially faster.

That makes it politically a complete non starter

Ideally we'd look at ways to avert the climate change destruction that doesn't also involve destroying relatively rare habitats in the process (and one slightly non obvious issue is that if we went all in on tidal then it would be the same sort habitat in all the locations we used - potentially impacting a large proportion of that habitat globally.

John Robson Silver badge

Re: Caffeine or no caffeine

"Nobody is arguing about *today*."

Neither was I - except to point out that you were correct: Hydrogen is already used in fairly decent volume - the assertion that you were countering was the we'd ever get to 2GW of hydrogen usage.

You accused cyberdemon of being childish and insecure, and then failed to address the (valid) concerns raised.

That's not fact based - it's why I suggested turning down the petulance - because you have good things to say.

Hydrogen storage is a significant barrier to long term energy storage as hydrogen, distribution is also a barrier although many use cases don't actually need long distance transport.

John Robson Silver badge

Re: Caffeine or no caffeine

Yes, a tiny minority of it is green at the moment.

I'm sure we can produce a very substantial amount of it using electrolysis, but storage and transport is the biggest issue - I'm absolutely with you there.

We can use hydrogen in gas turbines - somewhat less efficient than fuel cells, and will produce various NOx compounds as well, but it's a pretty well established technology... that just leaves storage.

Can we get to a 2 or 10 GW, or GWh, not quite sure what the target actually is?

No idea - but not without actually trying to do it, which probably doesn't involve bunging money at oil companies.

John Robson Silver badge

Re: Caffeine or no caffeine

It's also notoriously difficult to harness.

I mean if you are happy to completely wreck ecosystems then you can build a barrage across the severn, and that would generate a significant amount of electricity.

The La Rance barrage generates an average of 96MW (40% capacity factor, 600GWh/year), estimates for the severn are in the region of 2 GW (17TWh/year)

John Robson Silver badge

Re: Flow batteries

Current flow battery electrolyte density isn't really usable for mobile applications - it works great when you have a couple of really big tanks (TM)

John Robson Silver badge

Yes, in the same way that your body sounds alot like an engie - fuel and oxygen -> energy.

But the process is completely different to both of those comparisons, and fairly close to the electrochemistry of a battery.

My hearing aid batteries work in a similar way, though they use zinc as a fuel.

John Robson Silver badge

Re: Caffeine or no caffeine

Hydrogen already contributes about 2.6GW to the UK energy mix, and yes infectious diseases are still a thing.

John Robson Silver badge

Re: Caffeine or no caffeine

Turn down the petulance and you might have a point to make.

Green hydrogen is still a *tiny* proportion of the hydrogen we use today... but note that we *do* use hydrogen.

We use about 700,000 tonnes, at ~33MWh per tonne, annually. That's 23 million MWh, or 23 TWh annual usage in the UK currently. That's already an average of 2.6GW

John Robson Silver badge

Re: Caffeine or no caffeine

"What worries me about that plan though is that HVDC is asynchronous - by virtue of being DC - so it exacerbates the already perilous grid-islanding and frequency-instability that could cause a UK-wide blackout - and although we can sort-of fix that with some funky software, they are extremely vulnerable to sudden failure or sabotage."

I don't think we're in significant danger of islanding, whilst that AC backbone exists we'll stay in sync.

Indeed at least one Australian grid (which tend to be much longer and thinner than ours since everyone lives on the coast) is already down to only having two synchronous generators required...

"Subsea AC cables then? Maybe. Although apparently they annoy the fish even more than the DC ones do. And just-as-prone to anchor-dragging etc."

They also have efficiency losses due to induction, meaning DC is usually a better solution over longer distances.

John Robson Silver badge

"the huge losses"

You mean the <10% losses on the grid as a whole...

Yes, sub 10%.

Of course if you're electrolysis water to get your hydrogen you don't do it off the grid - you do it on the site of generation that is either dedicated, or would otherwise be curtailed, so even that 10% is a *massive* over estimate.

75% electrolysis efficiency, 60% FC efficiency (and this should rise with caffeine).

But the input can be renewables - the challenge remains that storing and transporting hydrogen is a pita.

For static long duration storage that's not as big of an issue, but for mobile applications it is.

Attacks on UK fiber networks mount: Operators beg govt to step in

John Robson Silver badge

Re: Death?

Well that depends on the mic.

There is no "this is always best" when you're talking about quite such disparate technologies.

You'll note for example that microphones on orator platforms are never pointed at the ceiling so that heads of state talk "across" them.

John Robson Silver badge
Facepalm

Re: Death?

In front of my mouth doesn't mean "in line with my plosives", or "in line with my exhalation", it does mean in line with the highest sound level. Of course most people have no mic technique at all, so I can understand the confusion.

The traditional position to hold a phone puts your voice directed away from the mics, so whilst they are designed to pick up from various angles, and they do exceptionally well at it, they are explicitly designed to pick up from directly below the phone, since that's where you're actually projecting your voice. The position is required when you are hearing from one end of the phone, and speaking at the other. Many early phones (see Mary Poppins) had the two features separated, so you'd talk *at* the microphone and hold a speaker against your ear.

If there is no constraint on where the phone needs to be held for the purpose of hearing the conversation (and there isn't in my case, since the audio is being directly injected into my ear canals) then there is no reason to hold a phone in the traditional position - so any position which gets the mics close enough to my mouth, and preferably in the highest signal area - is going to get equally good results.

To my memory I've only ever needed to do this once, and it also involved shielding the mic end of the phone from the ambient wind and noise.

The public use of speakerphone, however, should be strongly discouraged.

John Robson Silver badge

Re: Death?

Meh - how should I hold my phone Mr PhonePoliceMan.

The only part of it which matters when taking a call is the microphone, since the received audio is streamed to my hearing aids. Reception is generally not orientation dependent any more.

In most places the microphone is good enough that I can leave it on the table, or in a shirt pocket, or on the dashboard etc... but in a noisy environment I might want to make the mic as effective as possible, and that means in front of my mouth - pointing towards my mouth.

John Robson Silver badge

Re: Transportation

Rwanda's too good for them... send them to westminster... might actually increase the percentage of law abiding citizens.

European Commission broke its own data privacy law with Microsoft 365 use

John Robson Silver badge

Re: Kicking!

Automated doesn't mean "imposed".

Copying from a post I just made in response to someone else:

"BTW, if you have a speed limiter and you can disable it, it it then really a limiter?"

Yes - it's a "default cap", eliminates any concern about speed cameras without me having to think about it, and often I find that I'm manually holding a speed that's just one or two mph below the posted limit, because that's what feels like a safe speed. The point is that you have to make an active decision to speed, rather than just having your foot gradually slip down the accelerator - Call it an idiot check, but I make those all the time at various points in my day - "Do I have my bag, and my phone, and my keys" idiot check, but a manual one.

Having the limiter be controllable also means that on the occasions when something isn't correctly picked up (for instance there is a temporary works limit at a junction near me at the moment, and as I turn between roads at the junction my car thinks the default speed limit applies on the new road, when it's still within the temporary limit) then you can override it - whether that's down or up.

That deals with point a and b.

For point c - it doesn't need to be permanently recorded - it only needs to record infractions, in the same way it only records accidents. Maybe with an additional one or two item buffer of the latest visual and mapping based limit changes.

And yes, on the occasion that all the ambulances are on fire and I need to get a critically ill child to hospital I'll happily break the speed limit at various places en route, and have no interest in blocking that. But the speeding is then a _deliberate_ choice, not a casual "overran the speed limit down this hill" issue - and *that*, along with rigorous enforcement, would be a massive win.

John Robson Silver badge

Re: Kicking!

Ambulance availability is indeed critical - but that "on site" care is a winner whenever it's available, even if that's from a first responder who can usually get there pretty fast.

"There's one features in A&E that tells you how urgent your case it - if the triage nurse takes one look at the kid and immediately calls a doctor you know it's serious."

And when the reception nurse puts the patient straight into a bed without even calling the triage nurse - it's really serious.

"I prefer to pay a fine in that case."

Agreed, which is why that human control is important. Particularly given that it's far less dangerous to do 90 on a motorway than it is to do 30 or 40 in a town centre - choosing *where* to pick up time is a critical judgement call.

"BTW, if you have a speed limiter and you can disable it, it it then really a limiter?"

Yes - it's a "default cap", eliminates any concern about speed cameras without me having to think about it, and often I find that I'm manually holding a speed that's just one or two mph below the posted limit, because that's what feels like a safe speed. The point is that you have to make an active decision to speed, rather than just having your foot gradually slip down the accelerator - Call it an idiot check, but I make those all the time at various points in my day - "Do I have my bag, and my phone, and my keys" idiot check, but a manual one.

Having the limiter be controllable also means that on the occasions when something isn't correctly picked up (for instance there is a temporary works limit at a junction near me at the moment, and as I turn between roads at the junction my car thinks the default speed limit applies on the new road, when it's still within the temporary limit) then you can override it - whether that's down or up.

Stupidly I can't tell the car that I want the speed limiter to be the default setting, it always defaults to cruise control, so if I engage it without changing the setting first the car sets off to the speed limit...

Far better to have cruise control be the thing I need to set up manually - or just let me choose which is the default.

John Robson Silver badge

Re: Kicking!

"Yeah, I hope you never have a kid with a life threatening condition. Context matters."

I've had a kid in special care... context matters.

There are a few options

- Call a fucking ambulance to get the support you need as fast as possible.

- Drive within the law to get to the hospital

- Decide that a fine is worth paying and speed

That third is always an option - despite my vehicle having a speed limiter, which I always have enabled, all I need to do is either manually adjust the setting (using a stalk control) or floor it.

Having the speed limiter enabled by default doesn't mean that it can't be overridden, but you'd better have a damned good reason for doing so.

John Robson Silver badge

Re: Kicking!

You can't bring facts to an argument where the EU are concerned.

Personally I'd be all for automated speed restrictors, and black box speed recording. If you don't want to pay the fine, simply abide by the posted speed limit.

You'll have pretty good evidence of whether or not the speed limit was posted if the black box records that the car didn't see a speed limit sign...

Japan's first private satellite launch imitates SpaceX's giant explosions

John Robson Silver badge

Re: Please...

And only the "on pad" failure of an F9 comes close in terms of pad damage due to rocket failure.

Yes, IFT1 did "some" damage to the launch infrastructure, but not through failure of the rocket.

Watchdog calls for more plugs, less monopoly in EV charging network

John Robson Silver badge

Re: It is still not as simple as pulling up in a forecourt and filling up a tank

And in EV world you pay by:

- Bank/Credit Card, or

- RFID card/App, or

- The car deals with it entirely and you don't need to do anything other plug in

The only one that isn't generally available is cash, but I can't recall the last time I paid for *anything* using cash, so that's a small benefit.

I'm yet to see any of the major chains use the ANPR to automate petrol payment from people with accounts.

John Robson Silver badge

Re: I will purchase an electric vehicle - eventually

"Not so an EV. It could be taking a substantial portion of its 7kW non-stop for anything from a few tens of minutes to several hours. Many households have 2 or move vehicles so double or triple that."

Yes - but rarely.

Because you don't need to charge am EV from empty to full every day. Any more than you tip the fuel down the drain and fill up your ICEV every day.

Average car does ~20 miles a day, so needs about 5kWh, which is not a huge load. If we assume cars are at home for ~10 hours overnight then that's 500W needed.

John Robson Silver badge

Re: I will purchase an electric vehicle - eventually

"Storage heaters are generally in the 1 to 2kW range and are thermostatic so don't run all night, only for as long as it takes to "charge" up. They are generally used in smaller properties where the overhead of fitting a gas burner isn't justified so unlikely you'll get to a total of 7kW."

Mine is 2.3kW, and runs continuously during the timed period - whilst it does have a thermostatic "max charge" control - I've never hit that stat since I've been monitoring the energy usage.

When I had two of them on E7 via a time switch by the dual meters in my first flat then each of them would have been similar power rating, and they also ran most of the night in winter (though I don't have data on those).

"I want the radiators to be warm in the evening when I'm sat in front of the TV, not in the middle of the night when I'm asleep."

Not really - you want the *house* warm in the evening, a subtle difference, but important.

Heating load is much harder to shift, but is also substantially lower. At the absolute coldest (-8.6 degrees) we have had over the previous two winters my (fairly traditional british housing stock) family house used 5kW of gas over 20 hours - data shows that my boiler typically doesn't fire at all for at least four hours of the night. It used 5kW on just 5 days over two winters, that's maybe 2kW for a heat pump running at low efficiency (due to the low temperature) on 2-3 days a year.. There were only 22 days over those two winters needed more than 4kW (including the previously mentioned 5).

To supply our hot water would require the same power draw for a little over an hour in that four hour "break" that my boiler takes overnight.

Of course a modern house shouldn't need nearly as much energy - we are far too late in improving building standards.

It's quite easy to move any of that load by an hour or so to help the grid on days of particularly spiky demand/supply (or indeed every day if you have something like the Agile or Cosy tariff) just by turning the heating on slightly earlier, and then off for an hour - but you're right that you can't shift it to overnight without additional local storage - but we have the potential for massive additional storage, EVs can shift many hours of heating demand.

The energy consumption of heating is substantial, but the power draw isn't all that bad.

John Robson Silver badge

Re: I will purchase an electric vehicle - eventually

If only the national grid would think about this and model their network, and make plans... Oh, they already are.

Yes - heating is a much higher energy demand than EVs, but is also a load which the grid can handle, the "headroom" I have been describing thus far is headroom *already* in the system - no investment needed at all. Our heating load in this house, in the coldest of weather over the last two winters (-8.6 degrees), is ~5kW, which even with an inefficient heat pump (and it clearly won't be pulling a COP of 5 in the coldest weather) isn't going to exceed 2kW of electrical load; that's within the capacity of the distribution network - yes we'll need alot more generation, but that's a different part of the equation, and we'll have a whole stack of gas we don't use any more... Because burning gas in a power plant, transmitting that power over the grid, and using that electricity to run a heat pump gets more heat into a house than burning the gas on site. Is it the ideal fuel to use? Absolutely not, but as that gets phased out in favour of more zero carbon generation then everyone benefits.

"How much do you get paid for grid export? Peanuts as a fraction of what it costs to import that's how much."

My off peak import rate is 7.5p, my average import rate (total cost/total import) over the last six months has been about 10p, and my export rate is 15p - so yes its a fraction, but what we used to call a top heavy one. (That import rate is just the import, not accounting for export credits, DFS sessions, self generation).

That's also the "now" situation. Half hourly tariffs are really in their infancy, and the ability to have these tariffs dynamically adjust to the grid is still very new. Octopus Agile and Intelligent Go are good examples of two approaches being trialled:

- One where the price tracks the wholesale price, set each by the "day ahead" rate.

- One where there is a traditional "off peak" period, but also a completely dynamic "additional half hours" that can be given to you at effectively no notice at all.

Neither of those are the same as tariffs from twenty years ago, so why do you assume that tariffs in twenty years time will look the same?

"If it was ready and capable of handling it then why is there be a back-log of generation schemes waiting to be connected? "

Because you're asking why the tip of the chisel is blunt when I've said that the handle is comfortable. There is a massive difference between HV connections to new generation and the ability of the distribution network to handle as much energy as it handled twenty years ago.

Of course we're not yet ready for the load we expect to have in thirty years time - we'd be foolish if we were, it would be a waste of resources.

I'm well aware of toyota's defense of their old business model... and I have some sympathy with their BEV vs PHEV, but none at all with their fuel only vehicles.

John Robson Silver badge

Re: I will purchase an electric vehicle - eventually

"Cables to the house are already sized to supply whatever the house fuse breaker is set to - 100A so so. I have yet to see an EV that will draw more than 11kW off three-phase, or 7kW off single phase AC charger. 7kW is 30A - not to be sneezed at, but there are many induction hobs that draw this on the market already. And I note you're not suggesting the cables under the street will all need replacing if everyone cooks dinner at once."

To be fair there is an assumption that not all houses will draw maximum power at the same time.

But... we used to all draw substantially more power all day long than we do now - and storage heaters used to draw more than 7kW all night if you had more than one room in the house...

John Robson Silver badge

Re: VAT

Absolutely -They pump huge amounts at fossil fuel drivers - continuing the 5p cut, and the long term freeze on fuel duty.

Gridserve (the only network that I could easily find a figure for) claim to have charged 160 megamiles across ~2 million charging sessions last year.

Let's be conservative and assume that's 40 GWh (or 20kWh per session, seems maybe a little low)

They're the fifth biggest DC charge network, with about 10% of the total - let's assume that they're representative.

That's ~400GWh, charged at ~75p/kWh which is about £300 million in takings, of which £50m would be VAT - drop the rate to 5% (to match domestic charging) and you're looking at a cost to the treasury of <£40 million.

Assume that the AC network does as much charging as the DC network and you're still under £100 million

The 5p fuel duty cut which should have expired keeps the duty down to 53p, thats on 16 billion litres of petrol and 27 billion litres of diesel (RAC figures from 2023). That's £2,100 million - more than an order of magnitude more.

John Robson Silver badge

Re: Not a real problem

Well, I have to get the wheelchair out, then wheel down to the service station, navigate to the loos which always seem to be at the far end of a slalom/obstacle course of all the shops "extra display" space and food outlets... Then I go to the loo and have to do the same in reverse.

Can easily take 15 minutes.

Wrong fuel is something ~150 thousand motorists do each year, and that's those who get it wrong enough to need help.

John Robson Silver badge

Re: Home charging is worse

"If that's the extent of the aspiration then what a terrible missed opportunity"

Yep - the internal networking is deliberately disabled, presumably because if there isn't a network, then there isn't a hackable surface.

Having something which does that translation into the network is useful, and having APIs which whatever your chosen "hub" can talk to is useful.

John Robson Silver badge

Re: Home charging is worse

Yep - local connections should be standard.

And the APIs should interact nicely...

Smart meters should at least be able to do something like pushing MQTT messages out - I'd like my Octopus Mini to do that in fact...

John Robson Silver badge

Re: It is still not as simple as pulling up in a forecourt and filling up a tank

The market isn't a subsidy - though I agree that it is distorted. But some of those distortions are deliberate. The biggest distortion is that the cost of electricity is so tightly tied to the price of gas.

"Also, many tariffs are directly subsidised by other tax/bill payers, and i'd be surprised if you weren't using one with your eco green set-up. Heat Pump tariffs for example where a portion of your HP usage is subtracted from your bill.. Solar feed-in tariffs, v2g tariffs, DFS events, these are all directly susbsidised."

DFS isn't a direct subsidy - it's actively cheaper to pay people not to use energy (and this year to return energy to the grid) than it is to pay to warm up and then start generating from an additional power station.

I don't have a feed in tariff, or any tariff where some usage is subtracted - I have what's now called Intelligent Octopus Go, with a flexible gas tariff and a fixed export tariff. So I get six hours of off peak energy (good for things like the dishwasher and my storage heater), as well as any other times when it's advantageous for Octopus to charge my car at a different time of day.

Doing those few simple things means that over 80 percent of my electricity usage in February was from "low carbon" sources (based on my actual energy consumption compared with the national numbers from https://app.electricitymaps.com/zone/GB) - that includes a small proportion from my PV array. January was ~70%, December about 80%... summer will be much better. That doesn't calculate any "discount" based on exported energy.

The grid is pretty robust, and we have twenty years to increase capacity in those areas which need it most, and those areas are already known to the grid. inverter technology has improved to the point where we are not limited by sheer tonnage providing grid stability any more - one of the Australian grids are running trials last time I checked (though they still use non generating syncros if I recall correctly, and have a couple of small plants always warm).

Even in the UK LEDs are a massive win, my (midlands) heating is off for at least six months of the year looking at last year's gas usage figures - so fully half the time that heat is wasted... so a 90% reduction in energy usage is achieved. "But sometimes" isn't a good reason to leave things inefficient. You don't eat an elephant in one bite, you take it a spoonful at a time - LEDs are an easy win.

A heat pump COP of 3 wouldn't be considered good - and my calculations (based on 70k lines of raw meter data) are that even assuming that my boiler is 100% efficient (it won't be, it's a condenser boiler that's just shy of twenty years old) and I were to replace it with a heat pump with a SCOP of 3 (I would hope to significantly exceed that), and my heating electricity costs are at peak rate (I can do better than that) then I'd be a few hundred pounds a year cheaper with a heat pump than a boiler.

To be equivalent to a gas boiler in other terms I'd need the overall COP to be ~0.9 to match the efficiency of a good boiler - and even accounting for the <10% losses in the grid, and the ~50% loss in conversion at a power station... you'd need a "local" COP of under 2 (which would be _appalling_) to get to the stage where you "may as well use gas".

"Anyway, always a pleasure arguing with you Mr Robson. Have some upvotes and an e-pint :)"

Discussing, surely... ;)

\_/ \_/

John Robson Silver badge

Re: It is still not as simple as pulling up in a forecourt and filling up a tank

The grid itself can deal - we will need to increase generation, but the transition is going to take another twenty years or so, it's not happening overnight.

I'd like to see micro reactors at every service station as a starter:

- already good grid connections

- close enough to populated areas, but out of nimby zone

- substantial local demand as EV journeys increase

- distributed generation, with slightly increased rates near population areas.

We don't need to limit them to those ~100 locations either, but they'd be a good starting point. And it's one thing I hope that the hyper-scalers who are currently looking how to power their next generation of data centres can actually accomplish as a net positive.

But more generation of various (preferably zero carbon) sources is always going to be needed, because a substantial amount of our primary energy consumption isn't electrical yet. Of course there will also be some savings from not having run refineries etc - but that's relatively small beans.

When I say preferably zero carbon... if we took petrol that was delivered to the pump and instead burnt it in a power station, using that electricity to charge EVs... we'd get more miles out of it than we would have done by using it in ICEvs - and as we continue to decarbonise the grid, all of those EVs get "cleaner" every step of the way. It's also relatively easy to implement CCS at a few power stations rather than across a fleet of cars - and of course the air quality where people live would be far higher.

Shutting down coal is a good thing, not replacing them with other sources is the mistake - although we've had a very significant drop in demand... so if you had replaced them... then there would be power stations sitting idle.

John Robson Silver badge

Re: It is still not as simple as pulling up in a forecourt and filling up a tank

"Of course, the current concept of off peak pricing is something that will become much more difficult to sustain if the current ambitions to increase EV charging and electrification of heating continue. If through increasing off peak demand, and better use of flexibility then the demand curve becomes far flatter, then supporting a 4-5x multiple between peak and off peak simply isn't justified. Yes, there's need for payment to flexible demand/generation but that's not going to help much for EV charging that has to happen overnight, or heat pumps that because of slow response times and heat demand profiles are very inflexible without expensive storage."

EV charging doesn't have to happen overnight - there are approximately 23 hours a day when a typical EV isn't in use.

Yes - we need chargers everywhere, but especially with V2G an EV should always be connected to the grid when not in motion.

Heat pumps are also somewhat flexible - there is an ongoing demand during the day, but taking an hour or so off shouldn't significantly affect comfort, and will make a significant dent in instant demand. We can also pre warm places at the end of any low demand period. But if you have a car at home when you need your heating - than the idea is that you plug the car in, and it can power your heating if the grid is at peak load... the model is very different, and the ability to shift demand to match supply rather than the other way round substantially changes how things operate.

We won't have a static peak/off peak, but that's already going away, we have the ability to have dynamic costs with half hourly meters - I have a cheap rate which applies for some hours overnight, and then also at any time my supplier chooses - I also have an export tariff, although that is static at the moment.

My supplier could also (given permission) talk to my car, my EVSE, my home battery... and automate all of those things to ensure that the cost of supplying me is as low as it can be, indeed it can also make supplying other people cheaper for them.

John Robson Silver badge

Re: It is still not as simple as pulling up in a forecourt and filling up a tank

"It bloody well IS subsidised!"

No it's not - it's a commercial rate which is available to anyone - it's not a subsidised rate.

E7/E10 have had this concept for decades, and I've been on a variety of those tariffs over the years - I am on one at the moment.

Negative pricing happens when supply exceeds demand - that's usually because demand is low (overnight) and supply is up - and it's always been passed on to some consumers, but domestic retail customers haven't had the metering equipment to allow for them to take advantage of the fluctuations in the price on the grid. Now we do have that capability, and there are tariffs which track the wholesale cost of electricity.

Imagine if we have EVs rolled out - you'd never need to curtail output at a wind farm again, never need to pay to adjust supply to match demand, you can just encourage demand - energy draw can be decoupled from energy usage.

The rectifier in an EV on board charger is generally one of the least efficient parts of the charging system, those which are designed to push 350+kW are usually more efficient, they are less weight and packaging constrained.

"LED lightbulbs ... often quoted as an example of how energy efficiency is somehow an unstoppable trend, but it's bollocks. Especially if someone is using electric heating, for example. But even if not, the "waste" heat from their lightbulbs would previously have warmed them up enough to not need to stoke up the coal fire. Now, we have all these wonderfully efficient LEDs which produce no infrared and ironically cause people to turn on their gas-fired central heating because they feel cold."

Ah yes, the "but sometimes" defense. It is better to use a more efficient lighting system, and an efficient heating system.

If I replace 10 100W light bulbs with 5W LEDs then I have 950W of heat less in my house. However I can run a heat pump and only need to use 300W of electricity to get 950W of heat, so my total consumption of electricity has gone down by about 2/3rds and I am exactly as comfortable as I was. Though in the summer, and indeed most of the year, I'll actually have taken my energy consumption down from 1000W to 50W, that's a 95% reduction. So averaged across the year my electricity consumption is down by probably 80%, with no change in comfort.

No the "but for some of the year the waste is actually useful" isn't a defense. Even if I used a purely resistive electrical heating system, I'd still be better off, because all the time when I have lights on but don't need heating, I wouldn't be running the heating.