Posts by John Robson

Re: GridWatch

Many were, but explosion risks are still explosion risks, and they happened.

Yes, some still happen.

You know - we should probably stop pumping explosive gases into houses, we could use other mechanisms to pump heat into buildings and food...

Re: For many of us, hybrids make more sense than BEVs

"Zero locally is good, but let's not pretend they're zero."

They're not zero at the moment, but there is no reason that much of the remote emissions can't be lowered further, and they are already substantially lower than ICE anyway.

Every time we add more low/zero carbon energy to the grid *every* EV improves, an ICE doesn't get that constant improvement.

Re: For many of us, hybrids make more sense than BEVs

Vehicle tax is paid on tailpipe emissions, so yes they do pay vehicle tax, it's just at zero rate (as it is for various other classes of vehicle).

You could break the law and still not end up as cheap as an EV:

Given that various of the chargers around here start at 20p/kWh - your red diesel isn't that cheap anyway:

"Our average Red Diesel price for today, Thursday 14th September 2023 is 85.56 pence per litre (excl. VAT)." (from boilerjuice)

So that's 85.56*1.05 = ~90p/ litre for your red diesel.

At an average UK diesel efficiency of 43mpg that's 9.5p/mile, carwow reckons the best available in the uk is 74mpg (peugeot 208) at 5.5p/mile.

Those local 20p chargers... they're 5p/mile

Charging at home, that's around 2p/mile (depending on tariff)

The free chargers, well let's think...

So no - even by breaking the law, you still don't get to the point where you can drive a diesel more cheaply than an EV.

Re: For many of us, hybrids make more sense than BEVs

Then you don't understand batteries...

The cycles on an EV battery are finite, but so is the water in the ocean... there's an awful lot of it - and low rate charge/discharging (and 7kW is a pittance for battery pack that can put out 100kW+) in the "middle" of a battery does the least possible degradation.

You also don't understand how the electricity market works - you're not "donating", you're selling (or using in your own home) energy which you bought at a cheaper rate when grid supply exceeded demand.

Re: GridWatch

Nope - the other person who corrected my calculation made far better assumptions.

And you'll note that we're still under the previous peak grid usage... because we're using 80TWh less per year than we used to anyway.

The grid can cope with all cars going to BEV without exceeding it's previous load.

We do need to invest as heating demand increases - but we also need to look at technologies which are available to help the grid - cars should all have bidirectional grid tied inverters (the charger doesn't care what direction the power flows) - 33 million * 7kW is a very substantial amount of power to have flexibly available (and yes, I know that you personally drive a million miles a day and can't ever plug in, but the vast majority of cars can - and using even a small proportion of a battery as an arbitrage tool will help cover the cost of having a car for many.

Cars are not the only option for demand and supply flexiblility, but they are a very large source of it - simply because cars spend 23 hours a day parked up doing nothing... they are the low hanging fruit.

Re: GridWatch

And we had plenty of deaths as a result of using it.

You seem to be mistaking better understanding of what options are available, and the risks associated with them, for "mass hysteria".

We've also replaced a very significant amount of the pipework since then, and moving to a gas with a *much* wider flammibility range than methane, and a similar (slightly lower) ignition point (i.e. much easier to cause an explosion) is not something that people actually want to see - particularly not when there are better ways of using said hydrogen to power our homes (by using a large heat engine or fuel cell, and then efficient electrical modes of heating).

Re: GridWatch

It infuriates me, and I'm sure others, to see new houses being built now, on completely new estates - removing farm and park land - without solar panels, heat pumps, or any other appropriate technology.

How are we not requiring these things as part of planning permission?

It should be trivial, at the time of construction, to install a distributed ground source heat pump system - have the south facing and east/west split roofs made of, not covered in, solar panels - have at least a *space* for battery storage...

The cost of the boreholes is then reduced because - you're not working around anything else, you already have heavy plant equipment around, and you need slightly fewer than doing enough for each house independently.

The cost of the solar is reduced because - you're already set up to build a roof, you don't need to build a conventional roof first, you don't need rails or to cut holes in an existing roof, the cabling is easier etc.

Re: GridWatch

"HP's are simply not alternatives to combustion boilers in any property that is older than about 10 years (and for many newer ones due to the piss-poor construction standards the UK is famous for). Give me hydrogen instead. Forget retrofitting insulation etc. requires far too much attention to detail to be done effectively at scale. Hence failure of Green Deal etc.."

Erm - and why not - my 1940's house is well suited, I spent all of last winter, which included some pretty cold snaps, running my boiler at a flow temp of 40-45 degrees.

It was actually really nice, far less cycling of the boiler and heating. It also proved to me that I don't need to do anything major to get a heat pump when the boiler (which is fast approaching twenty years old) needs replacing.

A heat pump will heat any house - it will take more energy to heat a less well insulated house, but all that really means is that the energy savings from a heat pump are even more significant.

Should you insulate first? yes, absolutely - but it's not actually a requirement of a heat pump that you have a certified passive house.

Hydrogen is a non starter in domestic systems - it leaks *really* easily, and you can't put an odourant in and expect that to be a good warning... because the hydrogen will leak *well* before the odourant does. It has a place in the future of energy, but the home isn't it.

"EV's might be closer to being viable"

More than closer, they are already viable - in fact they are already way better than ICE vehicles.

Re: GridWatch

"The weather is pretty much the same all over Europe at any given time."

Yes that's why we had a really hot July alongside the heatwaves that were killing people across southern Europe - Oh, no... we didn't.

We do have countries that rely on AC in the summer, but don't need heating in the winter, and we do have countries that do the opposite.

And Europe also borders Africa, which would improve the balance further.

Re: XLinks

Ah yes - unlike all those pipelines, oil rigs, tankers... those are of course immune from attack, and have no environmental or material cost at all.

We're going to have a grid of grids across the world (or maybe a couple) - get used to it.

Australia might not join in much, but they have a particularly good balance of negatively correlated generation options.

Re: XLinks

No - it assumed 12 hours of generation a day - which is about right for the Sahara (source: the article you linked)

It's fairly obviously not a practical proposition to concentrate all the solar generation in one spot - it's an illustration of how much energy we let go to waste.

Re: For many of us, hybrids make more sense than BEVs

On the basis that it's simply not needed... no.

Whilst EVs will place a load on the grid, the larger load is heating.

And we've got 20% headroom on the grid (in that 18 years ago we consumed 20% more electricity, and I'm not aware of a large scale grid deconstruction project)

Re: GridWatch

Quite possible - lots of zeroes around, and silly units (that's one reason I showed the working)

If you're right then it's still less than the demand from 2005, and heating is still a higher load (and an even more challenging one than that because it's concentrated into a third of the year)

Re: GridWatch

"Contrary to popular belief, cycling carbon around the carbon cycle is an essentially harmless activity; it is inputs of fossil carbon into the carbon cycle that are causing the problems."

Again - it rather depends...

It's not harmless in towns - not because of the carbon dioxide, but because of the other products of combustion.

It also requires that we maintain the ecology of a region - no good strip burning a forest and replacing it with concrete.

If you're somewhere where you have enough woodland to support you gathering fallen wood through the year to burn in winter then you're probably good - but we simply don't have enough woodland to do that.

Re: GridWatch

- Average annual mileage in the UK: 7,400 miles (and even that might be an over estimate looking at recent MOT data)

- Number of cars in the UK: 33.3 million

- Average efficiency: say 3.8m/kWh (I usually use 4, it turns out that it doesn't actually matter what number we choose here...)

That's a total of 2.5 tera miles, or 658 GWh/year

That's compared with a 2022 electrical demand of 321 TWh, which is down from the 398TWh we used in 2005.

All cars going EV* would adds about 0.2% to national electricity demand - assuming we haven't actually reduced grid capacity by 20% over the last 18 years it certainly won't push the grid beyond breaking point.

* Yes I'm ignoring that ~3% of cars are already electric - it doesn't make a significant difference.

---

If you really want something to think about it's how we deal with electrification of (domestic) heat - that's hundreds of TWh a year, and concentrated into the winter months.

80% of that demand is currently direct fossil fuel. Converting to electric we can reduce that demand to well under a third of the current levels (since boilers etc are not 100% efficient but a heat pump will be over 300%), but it's still a substantial additional load, particularly given that it's concentrated.

Watson et al. looked at peak demand and peak heat demand was ~170GW (40% lower than previously thought), which needs about 50GW of electricity generation and transmission.

So yes, we will need to invest and upgrade the grid over the next few decades, but mostly for heating loads, not transport.

Re: For many of us, hybrids make more sense than BEVs

Well if you decide that there are no interconnects and that there will be zero generation from anything else... yes it's a significant capacity required - but that's a completely unrealistic scenario.

Let's have a look at a distributed system... EVs - average is ~50kWh at the moment and there are more than 30 million registered cars in the UK which spend 23+ hours a day parked, and do just 20 miles a day (~10% capacity).

That's 1.5TWh of storage which we should already be mandating to have bidirectional 7kW AC inverters.

Single site 100MWh chemical batteries are already online in the UK. Long term storage won't look like that though, it will be things like opening up gas reserve storage for hydrogen, methane, ammonia or whatever else ends up being the most useful storage product - we used to have 500 billion cubic metres of storage - that's an awful lot of storage available.

The XLinks project is looking to add another 3.6 GW interconnect to remote solar and wind generation.

We *know* it hasn't been built yet - that shouldn't stop us moving towards it, and building it as we go.

There is no need for "lockdowns" to curtail demand... just planning as we get to the point you fear, where burning shit isn't our primary form of energy generation.

Re: GridWatch

Did I say that *all* of their generation would be imported?

You don't need 100% capacity interconnect, because you always have local generation - your interconnects deal with peak loads.

As more and more renewables are built then we will want to increase interconnects, though increased storage will decrease the interconnect size required.

Crikey - it's like people 120 years ago declaring that "we haven't got a complete motorway network so cars will never work".

Re: For many of us, hybrids make more sense than BEVs

I took a look at my local chargers, and none of the AC chargers exceeded 55p - several were lower than that, some down to 20p and others were free.

DC chargers are *not* what you use if you can't charge at home - they are what you use on a long journey (a handful of times a year).

Re: For many of us, hybrids make more sense than BEVs

The point of switching to per minute rather than per kWh was that Tesla could get more throughput at the chargers... it's not in their interest to have you sitting there whilst the vehicle has derated to <10kW.

People sitting at a charger getting from 98-100% for twenty minutes whilst there are people waiting to charge is just stupid and needs to be dis-incentivised.

Neither method is a cure all.

Re: GridWatch

It's really not hard to see fossil fuels displaced for transport, it's already very possible for everything other than air freight.

Transport is a drop in the ocean compared with heating over winter - that's the real challenge, but it is usually accompanied by wind.

However, even if we simply changed out boilers for heat pumps and used the gas in a power plant instead of in homes, we'd still reduce the amount of gas we burned... and on the many weeks of the year when we don't need to burn that gas (because renewables will be sufficient) then we can reduce it to zero. Similarly replacing gas hobs with induction power from a gas power plant wouldn't save gas, but it's pretty close to a zero sum, and obviously improves the lower carbon the grid mix is.

Both of those also have very significant health benefits for society.

The west coast of the USA and Canada has a massive interconnect, connecting the hydro power in Canada with the wind power of the western states with the solar in California - that's really nice, because California and Canada have almost opposite load cycles - Canada needs heat in winter, California needs cooling in summer. If you can connect east to west as well then you get a further spreading of load cycles and a spread of solar generation.

The idea is to build more than enough generation capacity, a diverse interconnected large scale grid, and to invest in storage - some of that will be battery based, with some very fast response units for second by second balancing of the grid, and others which are designed for day/night smoothing/arbitrage.

The long term storage technology "winners" are less clear, but is one of the few areas where there is likely a role for hydrogen (electrolysis in times of over supply, and fuel cell/combustion in times of under supply). Obviously the better round trip efficiency the better, but it doesn't matter hugely if it's not very efficient (30% or so is OK).

Re: For many of us, hybrids make more sense than BEVs

Several days isn't an issue - it's several weeks that's an issue.

Re: For many of us, hybrids make more sense than BEVs

So you're advocating for charging by the unit instead of by the minute? When it's occupancy that might be the "real" cost for the charge operator - after all if you sit there until your battery is full you'll be pulling less than it's max rating.

That was one of the main points raised at the time - you pay more for slow charging - so you want to always charge as fast as is reasonably possible.

That's kind of the point - you encourage short stops and fast charges, which also happens to be the fastest way to achieve a journey.

It's not all that common for chargers to derate, though I have seen it happen. Normally it's the car that does the derating.

Re: For many of us, hybrids make more sense than BEVs

per minute in lieu of per unit charging I've seen (or at least "pay to park in the car park, the charger is free", though I've also seen the "pay for the charge and the car parking is free")

Never seen kWh + min.

Re: Someone with a clue :)

Less and less worried about grid stability - because most of the loads we are adding to the grid can actually help manage the grid.

I am waiting for frequency based billing to be a thing - the price of importing/exporting electricity can move when the frequency drifts up or down - particularly with V2G capable vehicles you get a very good distributed grid balancing system.

Re: For many of us, hybrids make more sense than BEVs

5 hours at 7kW is 35kWh - let's assume you only get 30kWh into the car in that time... So you get ~120 miles of range added every night.

That's six times more than the average car in the UK.

Don't assume efficiency comparisons, just do pennies per mile - Petrol is about 17p at the moment, for which an EV would need to be paying well over 60p/kWh.

Most public chargers are less than that, substantially so - you're just only aware of the DC chargers which aren't the appropriate chargers for regular public charging users.

14p/kWh is pretty high for an overnight rate.

Re: For many of us, hybrids make more sense than BEVs

And FF duty could rise even more steeply.

Your point is?

Re: What's the matter down-voter?

That's exactly the kind of facility somewhere like the NEC needs - you're not there for twenty minutes (heck it takes that long to get from the car park to the NEC).

DC should basically only be needed at service stations - at least in terms of the really fast stuff... There is a place for 25-75kW DC at food places (i.e. somewhere you'll be for an hour), but basically every car park should do 7kW as widely as they possibly can (even if those balance down to 3kW if the car park is really busy)

Re: For many of us, hybrids make more sense than BEVs

"all paid charge points have a large per minute tariff on top of the kWh charge."

Can you point me to even one?

I've *never* paid a time based charge in more than three years of driving an EV.

There are some where if you stay a *long* time, or past your car's reasonable charge time, then you'll get charged per minute.

There was also a discussion about whether Tesla were going to start charging by minute rather than by kWh...

Re: For many of us, hybrids make more sense than BEVs

So you're assuming 3m/kwh? Wow... no wonder you think EVs are expensive... despite driving a first gen MG ZS, which isn't exactly aero efficient, and doesn't have the best battery management I get *well* over 3, nudging 4 most of the time.

Depreciation on any vehicle is ruinous, that's why most people don't buy new.

With 4.54 litres in a gallon and £1.53 (current RAC UK average for petrol) at 40mpg (being generous here, for petrol the uk averages 36, for diesel it's 43) that's 17.3p/m.

At 3.9m/kWh that would need public charging to be 67.8p/mile.

For DC fast charging Gridserve charge 69p, Instavolt 75p, Telsa 60p - so they're there or thereabouts.

BUT... those aren't the chargers you'd use for all charging if you couldn't guarantee charging at home (which is where this started).

You'd find AC chargers at places you visit anyway (supermarket, shopping centre, gym, train station, cinema... wherever), or better still at your place of work.

Local to me there are several free chargers (and that's a price hard to beat)... and those which charge start at 20p, but none are over 60p.

Of course if you can charge at home (like the vast majority can) then you're looking at under 2p/mile.

Re: For many of us, hybrids make more sense than BEVs

Something like 75-80% of vehicles in the UK are able to be parked off road at home (RAC figures I'e quoted often here)... a good proportion of the rest will be parked at work for good portions of their life.

Yes, we need much wider distribution of AC chargers... AC because they're cheap to install and therefore cost of energy through them can also be cheaper (and usually is), and because if you charge every time you go shopping, or eat out, or go to a show or...

"Did I mention that public charging points will be far more expensive to use than overnight charging at home?"

Did you mention that they're still cheaper than petrol?

Re: Do not want

So you're choosing to curtail production rather than sell the excess to, for example, cover your standing charge.

Why would you not want to sell something that you are producing and cannot use?

Re: Battery sharing?

Yes recharge cycles affect battery life - but we're talking about a) getting paid for it and b) 0.05C charging

You're not going to kill an EV battery by using it as a grid supplement.

Charge cycle for a 50kWh battery would normally net ~200 miles

To run that cycle as grid export would take ~7 hours continuous full rate export

Let's assume you use 50% of the battery as arbitrage each day, knowing you want the other 50% for driving - that's 100*365 miles in a year or 36k miles a year. So after three years you've done 110k miles of *extremely* gentle charge cycles.

You've also been paid for 9MWh of electricity, and imported 9MWh. Depending on your provider, you might get paid for that capturing surplus generation as well as paid to provide at times of peak demand - an arbitrage rate of 20p would net you nearly 2 grand.

And you still don't need a new battery... you know why - what happens to a battery that's done 200k miles? Well, it has slightly less range than it used to, but still plenty for your daily driving needs, or if not yours then someone elses.

Re: Reuse landing on the Moon

For reference if we assume just 300s of specific impulse, a 100t dry mass, and 3km/s requirement after landing (gives 250m/s margin for getting back to NRHO).

NASA are happy with Blue Origin's 20 tons of payload...

SpaceX have said "up to 200 tons".

So that's between 120 and 300 tons of mass to get back to NRHO, needing between 205 and 515 tons of fuel, for an all up landing mass of 325 and 815 tons.

I was putting my finger in the air when I said well under 1000 tons, and looking at the maths, I was right.

Re: Reuse landing on the Moon

Starship dry mass is 100t, not 200t - and the lunar version doesn't need flaps or heat shielding - it's not designed to get back to earth at all, it only needs enough fuel to land from and return to NRHO (i.e. land with ~3km/s)

It's not that hard to put some smaller methalox engines up there, it's still rocket engineering, but of all the challenges it's not a show stoppingly complex one. It was used on their proposals - and with or without them, there isn't an issue. The plan was to use gaseous methane/oxygen fuelled engines, which allows them to avoid complex plumbing.

Three vacuum raptors, operating throttled way down in a vacuum do not pack the same energy or damage potential as 33 sea level raptors at 100% thrust in a full atmosphere of pressure.

Re: Reuse landing on the Moon

Well you start off with the dry mass of the ship (not the booster), then add on reasonable cargo (organic and otherwise) and fuel to reach NRHO... and come up with a number well below 1000 tonnes.

You then look at the proposals and see the sets of engines mounted way up near the top of the main tanks, and realise that the system will barely breath on the regolith.

Re: Cost

"Even Rocket Lab is doing some half-assed thing with parachutes and fishing the booster out of the water."

They have a very different problem to solve - parachutes for small loads are well established, the F9 booster is far too large for that to be realistic, but the fairings do use them.

The Electron booster is somewhere in the middle... and not having to deal with engine relighting in flight is quite a benefit if they can get away without doing so.

Re: From inattention to immediate crash?

Yes - disengage is the worst possible response... pull over and stop - then refuse to *re-engage* for 48 hours would be far more appropriate.