I like the idea of the buses providing power back to the grid when they're not being used in the late afternoon, but the article's author seems to think that even privately-owned passenger cars should be participating in this as well.
I'm not sure how practical that would be, though. For school buses it's easy, because you know exactly the range of times during the day, every (week)day, when they're going to be out on the road. Late afternoon/evening use as a grid source is perfect, because they've already brought all the kids home, and won't be needed until the next morning, and there's plenty of time to charge them back up after they've sent energy to the grid.
But for my own private vehicle, I don't use it on a schedule. Well, sure, there's some scheduled use, but there's also random unplanned use, or even just random planned use that might not conform to when the grid wants to pull from my battery. If I'm leaving at 6pm to start a 3-hour drive to visit out-of-area family for a few days, for example, I certainly don't want the grid pulling from it, say, from 3pm to 6pm.
And on top of that is battery wear and tear. I would assume that, all else being equal, a car participating in a vehicle-to-grid program will need its batteries replaced sooner (maybe much sooner) than a car that isn't. And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner.
You might not use your car on a schedule, but if you aggregate thousands of private vehicles you can build a statistical model that gives you pretty high confidence that a certain amount of charge will be available.
Yes, the fraction of total charge that you could plan on being available this way is going to be a lot smaller than the school buses, but there is a lot of electrical energy available in EVs so even a small fraction of it is a big deal to grid stability.
Furthermore, a lot of the potential for EVs as grid balancers isn't for the day-to-day variations in supply/demand - it's for those few hours a year of demand peaks, and in open electricity markets the wholesale price of electricity goes to pretty crazy levels (thousands of dollars per megawatt-hour depending on the market design). Those few hours of crazy-high prices pay the costs of peaking generation that only operates at those times.
In Australia, the market is capped at $15,000 per MWh. Say you configured your car so that it would sell back into the market only when the market was above $1000/MWh.
In one winter month I looked at, applying these rules you could make about $60 from a total discharge of about half the car's battery capacity (and not all of the high-priced period was contiguous).
That sounds like adequate compensation for fairly minimal degradation of the battery capacity.
You're right that it could be constructed in a way that would be more than fair, even attractive. And I would think that some kind of app that let you block out times would solve the "don't drain my battery if I might need it" problem (You could schedule it to be unavailable to the grid on a date when you plan on leaving for a vacation after rush hour, and never enabled on Thursday nights when you drive a long distance in the evening)
The GP though is probably right that our [insert expletive] utilities would pull the same type of crap they did nerfing net metering and find a way to rip off those participating in the scheme. Power is worth what, 46 cents a kWh now when I'm buying it, but if I had panels and was selling it during peak A/C usage time, suddenly it's worth 6 cents right. Uh huh.
All those same concerns apply to the existing Tesla virtual power plant's (VPP) in California and Texas. People buy Tesla power-walls to have emergency power that would be useless if their battery has been emptied by the VPP. And those PowerWalls are more expensive per kWh than a car is.
The solution for the first is a simple power limit, typically 50%. So the VPP never drains the battery below 50%, leaving a nice margin for emergencies.
The solution for the second is pricing: the VPP typically pays 50 cents per kWh, in return for about 0.1 cents/kWh of wear and tear on the battery.
Do you happen to own an electric vehicle? Modern EVs simply have tons of battery. My newest EV has the equivalent of 5.7 Powerwall 3 home batteries. Much of this is excess - if you commute 50mi/daily, given the range at 80% is est. 300mi, that's 5/6 of the battery remaining (assuming I charge it nightly which I do).
Also if you need to drive long-distance, there is fast-charging infra out there.
Sure, people should be incentivized to share - but if we did (say at 3-5x the max rate) then you'd have tons of people sign up. Make this a win-win and it'll be successful.
> And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner.
But maybe it would be different during peak usage hours (when solar is unavailable).
> All the while, fiercer heat waves will require more energy-hungry air conditioning to keep people healthy. (Though ideally, everyone would get a heat pump instead.)
An air conditioner is a heat pump. I'm not sure the distinction they're trying to make here. What we normally call heat pumps can provide efficient heating as well, but that's not relevant in summer. Modern heat pumps can be more efficient than older ones, but so can modern air conditioners that don't have a heating cycle.
The "fiercer heat waves" seems to be referencing global warming. Using fossil fuels or resistive electric heating during the winter contributes more to that problem than using an efficient heat pump.
> “They have more energy in each bus than they need to do their route, so there’s always an ample amount left over,” said Rudi Halbright, product manager of V2G integration at Pacific Gas and Electric Company, the utility that’s partnered with Zum and Oakland Unified for the new system.
This just sounds like the batteries are oversized for the application and they're carrying unnecessary weight around all day. Consumer EVs are doing this to an insane degree all day for "range anxiety", but I can't help but think that well defined space like school buses could be sized much closer to the true requirements.
The buses will all have different length routes, you aren’t going to custom build a bus for a single route and then have it be impossible to reassign later. The batteries will also degrade over time so you wouldn’t want them left completely useless when they degrade 1% and can now no longer complete the route.
To some extent, definitely. But I'd like to think that
1) School districts could buy a mixture of different ranged buses to fit their needs. After all, airlines have a mixture of planes in the fleet for different range / needs and not just have all the fleet be the largest / longest range model, and
2) The manufacturer offers range conversions later since it's a more commercial use than consumer EVs, especially when they want to sell it to different school districts. They probably need to do battery swaps when batteries degrade beyond a certain degree anyway.
Carrying additional capacity takes a lot of material (that could be used for other batteries especially) and energy. I get that it's convenient, but I hope folks put a little care into it than just put large batteries everywhere.
Perhaps, but there's a reason that anyone in supply chain or logistics tries to standardize on the fewest SKUs as possible. Planes are a special case because weight _really_ matters and thus it's worth the loss of standardization.
Imagine the nightmare of what happens when a driver grabs the wrong bus and is several miles along their route before they notice. Do they return to the school? Do they get as many kids as they can before they run out of charge while a dispatcher furiously tries to coordinate a place within range but still further along the route to send a whole new bus to switch the kids onto? What happens when the driver who's bus got taken drives off in ANOTHER driver's bus, perhaps with the same results cascading onwards?
Currently you have to balance drivers, bus capacity, and bus breakdowns/availability, but you don't have to manage bus charge because the gas range is large enough and the driver can quickly top up if needed. Adding another dimension of complexity into it likely isn't worth it compared to the cost of having a somewhat larger battery.
City buses in many districts are tied to their operator's licenses, displayed somewhere in the buses; same with taxis in most places I've been (prior to proliferation of ride shares). Not that they need to be tied to a vehicle necessarily, but I don't see why you think school bus drivers wouldn't be capable of getting into correct vehicles nor why that should be how a district picks a fleet of buses.
Also, for the SFMTA[0] as an example, different routes use different vehicles depending on the size & route & electrification. It doesn't have to be air travel to want a few varieties to fit all the needs.
Here are some stats[1, page 3]: An average school bus route is 32 miles, with max observed being 127 miles (and this is most likely a very rural route, not like the Oakland example here; in fact, here's an average of student distances for Oakland[2]). Given such a long time period between school start and end times, I expect most of these to be able to be charged between the two shifts with the exception of some field trips.
If you look at the Zum website, their buses are capable of 155 miles[3]. I suspect this was designed to fit the highest range case described in the paper, but almost 5x the average route distance. For most non-rural school districts, even if you account for some detours and faulty charging even, x2 (or x3, sure) seems reasonable to keep as the majority of the fleet. And perhaps you can keep a few of the largest range ones if the school regularly has field trips in that range.
For what it's worth, ETOPS regulations are interesting look for how aviation deals with failure modes for range/routing. Assuming failures are rare, the idea is to ensure the planes have enough to get to safety, not just put as much range as possible on all the planes.
Also having extra range is handy for sudden route changes, like a road closure or a train. In my home town it was a pretty long detour if you needed to get around the train
You're also neglecting the eventuality where the moment a district needs more buses with a minimum range above some threshold, they need to sell some buses (probably at a significant loss) and buy more new buses. And those new buses need to be compatible with all of the existing systems.
You don't want a fleet of twenty vehicles that need eight different sets of parts. You want a fairly uniform fleet.
I did not suggest that they have twenty vehicles either. I replied on a different post, but an average school bus route in the US is about 32 mi[0]. Zum buses are capable of 155 mi[1]. Given their "up to" language, I'd like to think that they actually offer smaller battery capacities as well, but especially for a non-rural district like Oakland[2], if one were to carry 155 mi range for a typically 32 mi or less route, it would be quite an overkill.
One can have a few 155 mi range vehicles for field trips, sports games, etc. but the majority of the fleet can be much smaller for every day uses.
Not necessarily. The battery may be able to provide power to the grid when it's low and does not enough power to drive the bus. The bus probably requires some minimum voltage to move and a bit more to be able to climb hills. And of course you don't want to run out of power so more buffer for that. So it's not unimaginable a bus could be near empty for the purposes of driving the route but have useful juice to give the grid. Fair question would be how such discharging affects battery lifespan
It’s not just range anxiety. You need to have extra capacity for cold weather and degradation over time.
If I have a car with a 300 mile range, and it’s 0 degrees outside, now I’ve lost a solid chunk of range, I’m down to the low 200’s
Then, if the car is 15 years old, I’ve lost another 10-20% of battery capacity.
But I also need to stay below 80% charge or I’ll double my charge time, so really I only want to operate between 5-80% on a road trip.
Now I have to charge every two hours of driving or maybe even less.
Compound that more if I need to tow something, put a kayak on the roof, put a bike on the back, etc.
So if I’m starting from an EV that has a more reasonably sized battery pack delivering 150 miles of range, well, maybe I can tolerate that but not in the winter 10-15 years from now.
Of course this discussion isn’t extremely relevant to school buses.
>All the while, fiercer heat waves will require more energy-hungry air conditioning to keep people healthy. (Though ideally, everyone would get a heat pump instead.)
I think this author is effectively saying that the devices that are widely known as 'heat pumps' tend to be more efficient than devices that are widely known as 'air conditioners'.
Technically yes, refrigerators too. Around here (Australia) we call it 'reverse cycle' when air-conditioners can heat as well as cool, and probably over 90% of all air conditioners in homes have that functionality - it's just expected. But the term 'heat pump' seems to be used in a lot of places now to refer specifically to having the heating ability, even though cooling is doing the same thing (just in the opposite direction).
Reading the article, it's clear the reason is the state froze the budget in 1982 and left it that way for 40 years. As with everything else in California, they could have done something about it, and didn't.
I'm sure the reason they froze the budget, though, is because they couldn't fund it further. Whether or not the lack of growth in funding is due to Prop 13 is not something I care to figure out or verify, but it sounds plausible.
The article also states that the growth of the fund is legally limited to cost of living increases.
Since this is a state wide law for a state defined budget, the solution is simple: repeal the law (which they did in 2022) and allocate funds to it from a different program, or with a new tax, such as a sales or income tax increase.
This is how they do a lot of things. I seem to recall at one point a rep wanted to add a tax to blueberries so they could create a blueberry commission to advertise California blueberries in other states. I think they do this already for other crops like avocados, though I'm not sure if it ever actually became a thing.
In any case, all of the legal levers have existed to fix the problem. They simply chose not to.
Even though electric buses have lower energy costs at about $0.213 per mile, over 1,000,000 miles, an electric bus could cost up to $985,782, while a diesel bus may cost as little as $488,000 due to lower upfront costs and no need for $50,000 to $60,000 battery replacements every 175,000 miles. Additionally, the environmental toll of lithium mining for electric bus batteries, which contributes to soil degradation, water shortages, and toxic chemical pollution, makes the long-term sustainability of diesel buses more compelling.
This is an unfair comparison. For some reason, you're willing to bring up environmental costs of electric buses in addition to the higher costs, but only mention the lower upfront costs for diesel buses. Diesel burning has an incredible high cost to the environment too, the main climate changing one we're grappling of course.
1. School districts do not drive their buses to 1 million miles. That's like 40–50 years of driving. Plenty of other components in a bus fail before then.
2. Electric vehicles do not need battery replacements other than manufacturing defects. They degrade for sure and hold less charge after time, but not to such a great extent that a school bus will be unable to complete its daily trip.
3. Lithium from old batteries can be recycled and remanufactured into new batteries. Battery recycle plants are already here in the U.S.
As a road cyclist, this can’t roll out nationwide soon enough. Ancient diesel school buses are an environmental travesty for the kids… and for me riding behind them!
Became skeptical of the overall article at this line:
>All the while, fiercer heat waves will require more energy-hungry air conditioning to keep people healthy. (Though ideally, everyone would get a heat pump instead.)
Heat pumps and air conditioners are identical, with the sole difference being that the heat pump can _also_ function as a heater/furnace. Heat pumps are not more efficient than AC for cooling. If the concern is increasing heat waves and increasing need for cooling in the summer (as described), heat pumps provide no advantage.
This is an extremely basic technical point. Combined with the overall tone of the article, this reads like a PR fluff piece about the company providing the vehicles.
-edit in response to numerous comments- Yes, heat pumps are good (I have one in my home), and, as a repalcement for _total_ HVAC systems, can provide a pretty significant efficiency bump, and reduce emissions...but for the _specific_ case of increased cooling needs, they will not make _that problem_ more efficient or reduce emissions.
In other words, the fact that heat waves are increasing and we need more cooling has zero impact on the efficiency ganes/carbon savings of heat pumps, which are entirely from replacing _heating_ systems. And if the writer had understood this point, then an extremely minor change to the sentence would have conveyed the point. Although honestly, it's so orthogonal to the overall thrust of the article that it would have been better omitted entirely, in my opinion.
Not in the sense most people use the word "AC" or air conditioner.
If you mean it by what it actually does, it conditions the air to be cooler or warmer or have less relative humidity, then yes. In typical NA applications anyway if we are talking a specific kind (ones you hook up to potentially existing forced air system ducts or mini split types with in room units blowing conditioned air).
We heat with our mini split in winter and we cool with it in summer. And I'm in Canada so it gets pretty cold in winter. And if I said we had our "air conditioner" running in winter people would look at me strange.
A heat pump isn't more efficient than an air conditioner at cooling, because they're the same thing except a heat pump has a reversing valve.
For heating, running your air condition with a reversing valve so it cools outside and heats inside is often more efficient than a furnace, so that is nice... But irrelevant if we're talking about it being too hot.
And how does any of this apply to my comment? I said nothing about any of that.
I was commenting on the use of the word "air conditioning" for heating. Which is technically true but not used in that way by like literally anybody. In any regular use of the word AC it implies cooling.
Again, to be clear, yes the phrase is usable both ways. No regular person will use it that way. Get used to it instead of making technically correct points that don't help anyone.
They don't claim heat pumps are more efficient than plain AC at cooling. Their parenthetical remark about people should ideally get heat pumps, links to an article about why people should get heat pumps. And why? Because they can have lower ghg emissions than natural gas furnaces and resistance heating through efficiency and the ability to use renewable electricity.
You're correct, but OP's misunderstanding stems from the fact that the parenthetical isn't just a tangent, it's a non sequitur. Humans tend to assume that an utterance is relevant to the topic at hand and in particular to the surrounding context [0].
This parenthetical was inserted arbitrarily in order to plug an article that has little relationship to the surrounding text, and OP understandably interpreted it as though the writer thought it was relevant.
> All the while, fiercer heat waves will require more energy-hungry air conditioning to keep people healthy. (Though ideally, everyone would get a heat pump instead.)
Juxtaposed with "heat waves will require more energy-hungry air conditioning", heat pumps are a non sequitur. A nonzero percentage of those energy-hungry air conditioners are actually heat pumps running in air conditioning mode.
"Everyone should get heat pumps instead" of what? Instead of a heater. As OP says, heat pumps save no energy during the summer, so they're entirely irrelevant here in a "though" clause.
> "Everyone should get heat pumps instead" of what? Instead of a heater.
You almost understand. The author is saying that if you're installing or upgrading your air conditioning, you should take the opportunity to also replace any heating system that isn't a heat pump, rather than only upgrade half of your HVAC system.
I understand that that's probably the connection the author was desperately reaching for, but what they were actually saying is "we have some other content over here that I'm obliged to plug, so here's a plug". And since the plug was the point, little effort was made to make the connection make sense.
In the abstract you are correct but in practical application, products sold as air conditioners and products sold as heat pumps are designed and sized very differently, resulting in different consumption/efficiency for the same home.
I imagine every heat pump can cool a house, even though every “air conditioner” cannot.
If you have a gas furnace to heat the house, then it might not make sense to pay extra for a heat pump that works in both directions (to heat and cool a house). So you would just buy a heat pump that works in one direction to cool the house, aka an air conditioner.
But if you buy a heat pump to heat the house, you might as well have the unit be capable of running in reverse to also cool the house (since you have no other way to cool the house).
I wouldn't really say very differently. Residential AC and Heat Pumps are available in pretty the same spec range. You can make an AC by removing/replacing some parts from a Heat pump and that's what some manufacturers do, meaning they're literally almost the same (except for the reversing valve, accumulator, outside meter and defrosting and some other small stuff)
> Heat pumps and air conditioners are identical, with the sole difference being that the heat pump can _also_ function as a heater/furnace.
That's a pretty huge difference from the user's point of view.
Take an existing house that does not have cooling, and has either fossil fuel heating or electrical resistance heating. The owners want to add cooling.
If they get an AC for that then later decide they want more efficient heating in winter the cost of doing that (whether by getting a new efficient heating system or by making the modifications necessary to add heating mode to their AC) are likely to be quite a bit more than than the extra it would have cost to get a heat pump instead of an AC when they were just trying to add cooling.
I wonder if some of the confusion stems from a seemingly common conflation of heats pumps and mini-splits. Mini-splits are not heat pumps per se though most of the former tend to be powered by the latter. And all other things being equal, mini-splits tend to be more efficient than centralized ducted systems since you're heating/cooling a smaller volume. But I agree that it's not clear the author understood the difference.
The “air” in “air conditioner” is describing what the function is. It’s conditioning the air. Plenty of ground source/geothermal air conditioning. It’s just a nomenclature thing.
Have you ever tried contacting an HVAC company and asking them to convert your AC to a heat pump so that you can use it to heat your house in the winter? I did, they told me that it was a nice idea in theory, but that it was the kind of work that nobody did unless they were teaching a class or something. The way to go is to just tear out my AC and have a heat pump installed. Nevermind that an AC is technically a heat pump.
So in practice, they're quite different.
> heat pumps provide no advantage
If you're worried about carbon emissions, heat pumps provide an advantage over AC / fuel-burning furnace combo's. I assume this is what the article was talking about.
In theory such a thing is possible. In fact, I've even sketched out what I'd need to do to my one to convert it. I may still do it as a science project -- it's an old unit (~2007), so if I destroy it it's not the end of the world.
I can completely understand why no HVAC company would want to touch such a project. It's entirely experimental, would take a skilled technician, and has a high chance of not working perfectly. They would much rather slap together 2-3 installs in the time it would take to plan and assemble your science project. Remember that most of their techs are literally just installers, and there's a huge incentive to "rip out and replace" rather than "diagnose and repair".
If you could find a retired HVAC tech, you might be able to convince them to help.
> Have you ever tried contacting an HVAC company and asking them to convert your AC to a heat pump so that you can use it to heat your house in the winter?
Of course not, that's like asking your car mechanic to convert your ICE car to an EV.
While the principle of operation in a heat pump and AC unit is exactly the same, an AC-only unit is missing hardware to be able to be used to provide heat, and it's not just a matter of replacing a part or adding an optional feature. It would require major surgery.
It's basically two 3-way valves to flip which coil has high pressure and which coil has low pressure.
If you get freezing temperatures, you may also need to do something to manage the icing that would happen outside, which may be via a suitable sensor to detect that state and running it in reverse for a calculated duration or such to melt the ice off.
It's really not much that needs to change.
Efficiency may not be too good in heating mode, though, but in spring and fall it should work much better than a furnace.
It takes more energy to bring a house up to 20°C in -15°C weather in a reasonable amount of time than it does to bring down the indoor temp of 20° from an outdoor temp of 35°C.
Their point still stands, which is that a heat pump provides no advantage in the summer, so the article was wrong in indicating that it did. But yes, not all ACs can be run as a heat pump.
I don't know where you get your ACs, but any I've seen installed this side of the turn of the century has a heating setting.
I use the AC unit (air to air heatpumps) in my attic mostly for heating in Winter and it works fine. The big downside is noise, (air to water) heatpumps let you move the noisy bit to another space which increases comfort.
You can build a silent-enough forced convection condenser to put in the room and put the noisy part away, without water, and cheaper than the passive convection water setup.
For cooling you can't use the typical passive convection radiators anyways, so might as well invest their cost into making the cooling and heating refrigerant coil silent...
Also c.f. a normal domestic fridge: no noise beyond the piston compressor.
Sorry, we can't improve school buses because Oakland is a shithole. Sorry, no space travel, Oakland is a shithole. No one is allowed to do anything good until Oakland looks like wakanda.
I think you mean "safer than East International Blvd."
I don't demand that you cite crime statistics by zip code, and compare the good ones to other cities. But that's what you'd need to do to be persuasive.
Most people understand that large cities have a variety of areas within them and the crime rate isn’t the same in the whole city. There are plenty of neighborhoods that have average to below average crime rates as compared to the rest of the US.
You're right - turns out as someone who's lived in Oakland for more than a decade I didn't know what it was like. Sometimes you need an outside perspective. Thanks.
In every school bus I've ridden on, two windows pop out as emergency exits, the rear door is an emergency exit, and there is at least one on the roof (in case the bus tips over). Buses are perhaps the easiest of all vehicles to evacuate in the event of an incident (except maybe motorcycles).
I'm not sure how practical that would be, though. For school buses it's easy, because you know exactly the range of times during the day, every (week)day, when they're going to be out on the road. Late afternoon/evening use as a grid source is perfect, because they've already brought all the kids home, and won't be needed until the next morning, and there's plenty of time to charge them back up after they've sent energy to the grid.
But for my own private vehicle, I don't use it on a schedule. Well, sure, there's some scheduled use, but there's also random unplanned use, or even just random planned use that might not conform to when the grid wants to pull from my battery. If I'm leaving at 6pm to start a 3-hour drive to visit out-of-area family for a few days, for example, I certainly don't want the grid pulling from it, say, from 3pm to 6pm.
And on top of that is battery wear and tear. I would assume that, all else being equal, a car participating in a vehicle-to-grid program will need its batteries replaced sooner (maybe much sooner) than a car that isn't. And given how utilities seem to want to pay less and less for power that residential solar sends back to the grid, I can't imagine any paltry sum they pay for vehicle-to-grid use would offset the very real costs to the car's owner.