Posts by John Robson 5210 publicly visible posts • joined 19 May 2008
The roadster was never meant to be anything other than a publicity stunt though - this is talking about useful deorbiting work.
Though given the oft quoted assertion that the exhaust gave useful thrust... we just need to feed the air intake (and ignore any of the other issues with working in a vacuum)
"Not to mention, finding the battery drained right when you want to go out because the power company decided to use your juice during the day."
So you still don't want to set a reserve level on your battery?
Nothing like holding up straw men as hard as you can because you know that you're asserting a pretty daft position.
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.
"I don't think very many people are going to want to use bidirectional charging, unless you have a Powerwall, because if you unplug your car, your house goes dark, and this is extremely inconvenient,"
More inconvenient than the house going dark when you have 60+kWh of stored energy in a convenient box?
Besides which, at the point at which you're umnplugging the car - you're probably leaving the house.
Use that LED to indicate that the house is drawing power from the car, then it's not a surprise when you unplug.
Such a dumb reason to not put V2G on their AC inverter.
"Windows, under all the marketing BS, is a very good OS."
Hmm - it would have to have improved a *long way* from when I last used it for that to be the case.
I'll be fair and point out that that's probably 15 years now - but I'll also point out that my daughter has a surface go for school (MS have almost always done good hardware) and the software is flakey when compared with the macs in the house (a bit unfair comparing it with the linux servers).
It's less flakey than I remember windows being, so there has been some improvement.
"But nobody is interested in funding that properly or overcoming the engineering challenges, because you can't make bombs out of it at the end."
And that's the big hope of these massive consumers wanting to build their own SMR/micro reactors.
Because they have the resources to actually overcome those challenges in the pursuit of cheap power to feed their habit.
Soil pipe - so a pretty big hole.
Mind you my first house was a concrete construction - and the aggregate they used was flint... I was going to chain drill holes for a dryer vent... and by the time I was a couple of inches into the wall with the first hole... the hole was about 4" across and was well lit internally from the sparks off the flint at the tip of the drill.
"In some cases, definitely some sort of Friday afternoon brick with neutron star density."
I recognise the pain - it took three diamond tipped core drills to get through the first ~1.5mm of our external brick... that third bit then managed the rest of that brick and the entirety of the inner brick.
"we've added progress indicators to guide people through the multi-step sign-up process and rewrote copy and labels to be more intuitive"
Pretty sure that should say rewritten rather than "rewrote".
"We've rewrote copy and labels" is not proper english like what my grammar tawt me
"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.
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.
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.
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.
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).
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.
"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.
"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.
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.
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)
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)
"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.
- 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.
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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.
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.
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".
"The original Honda Insight had this wonderful method of warming the hybrid battery when it was cold. It would just charge the living shit out of it! The higher the internal resistance the quicker it got back to working temp. You can treat NiCd batteries pretty poorly... for a while. Very few of those cars left on the road as amazingly the batteries died after about 6 years."
Wow - so you're looking at battery technologies that are no longer used, and a vehicle that hasn't been in production for more than 15 years.
You know what. horses don't work too well in -40 conditions either.
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).
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.
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).
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.
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.
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.
Well.. if they can nail the reuse then the launch costs will be fuel and mission control time.
Propellant is ~$1m for a full stack - and even an electron costs ~$5-7m.
Let's allocate a couple of million for "mileage" on the vehicle, and a further million for mission control costs, and the starship is still cheaper per launch than the electron, even if you just want to launch a single cubesat into a weird orbit.
The benefits of scale here are quite staggering.
And believe me there will be payloads that want the full capability, once it's available at a reasonable cost... then both commercial and military customers will want to use it... not very often, but it will get used. The other customer for starship is of course spaceX who need it to launch their V2 starlink birds.
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.
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.
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