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MIT study finds workplace charging and delayed home charging can mitigate electricity demand and cost

Large-scale deployment of battery electric vehicle (BEV) and photovoltaic (PV) electricity technologies could raise electricity costs by increasing peak evening electricity demand and causing overgeneration of electricity during midday. A new study by MIT researchers examines these risks and how they amplify or mitigate each other.

The researchers used data collected in two sample cities: New York and Dallas. The data were gathered from, among other sources, anonymized records collected via onboard devices in vehicles, and surveys that carefully sampled populations to cover variable travel behaviors. They showed the times of day cars are used and for how long, and how much time the vehicles spend at different kinds of locations—residential, workplace, shopping, entertainment, and so on.

The researchers modeled hourly electricity demand under BEV and PV adoption in the two cities, and then investigated mitigation strategies that do not require changes in behavior (i.e., travel) or new technologies such as vehicle-to-grid and networked chargers.

In an open-access paper published in Cell Reports Physical Science, the researchers reported that in both locations, delayed home charging nearly eliminated increases in peak demand. Similarly, workplace charging can reduce peak demand while also cutting the curtailment of photovoltaic electricity by half. These two approaches could be combined to suit local conditions and decarbonization plans.

They noted that capturing these benefits would require an acceleration of electric vehicle adoption relative to current rates.<>/p>

I think one of the fascinating things about these findings is that by being strategic you can avoid a lot of physical infrastructure that you would otherwise need. Your electric vehicles can displace some of the need for stationary energy storage, and you can also avoid the need to expand the capacity of power plants, by thinking about the location of chargers as a tool for managing demands—where they occur and when they occur.

—Jessika Trancik, corresponding author

The study was supported by the European Regional Development Fund Operational Program for Competitiveness and Internationalization, the Lisbon Portugal Regional Operation Program, and the Portuguese Foundation for Science and Technology.


  • Zachary Needell, Wei Wei, Jessika E. Trancik (2023) “Strategies for beneficial electric vehicle charging to reduce peak electricity demand and store solar energy,” Cell Reports Physical Science, doi: 10.1016/j.xcrp.2023.101287



For some years now I have argued that in the case of the US, home solar has been overemphasised versus solar at workplaces, where there are considerable areas which are not utilised and where solar canopies would not only provide charging for cars, but shade them so that less energy would be needed for keeping them cool in the first place.

It is still more expensive than utility scale, and had not got the grab of the somewhat fake home energy independence, which with past storage tech mostly meant fossil fuels doing the actual charging and relied on offsetting for its rather dubious claims of running stuff 24/7. Home batteries now change that equation, albeit somewhat expensively.

Workplace solar keeps the grid local, and saves the losses and expense of transmitting it long distances, so I see good potential here.

And TOU is a no-brainer, which chimes nicely with the abilities of our political masters! ;-0


Свершилось, все ждали этот Слив Онлифанс

Thomas Pedersen

It's really quite simple: BEV owners need to be incentivised to charge at the right time.

I Denmark I use the app linked below (in Danish, but you get the picture) that gives an easy overview of the purchase price of electricity, hour by hour. This is market price (by you own vendor), plus applicable taxes, plus transport tariffs, which have been made dependent on the time of day. So the cost midnight to 6AM could be 1/10 of the cost during 5-9PM, where most people a using lots of electricity to cook. Btw. every day at 1PM, the hourly grid rate for the following day is being announced, so you have 11-35 hours of anticipation. Beyond that, people need to resort to forecasts, mostly based on weather forecasts. Last night I charged my car from 30-55% in the hopes that the nightly rate will be lower in the coming days. There's really a lot of money to save by 'helping the grid'. I am very grateful for the opportunity to reduce my power bill with just a bit of vigilance.

This might be unpopular in the US, but in Denmark (and I guess in many EU countries), there is a central data collection agency that collects hourly power consumption data from each legal consumer (e.g. a house) and enables the owner to digitally allow 3rd parties to access that data - which is what I have done with this app and a central part of how it works.

It is possible to parameterize all relevant factors for the cost of bringing electricity to any given end point at any given time. And in doing so, the lowest cost will reveal itself, both to investors and to consumers.


Hey Thomas

AFAIK there is wide variance in what the different states in the US are doing about TOU charging.

Here is a rather old article:

Those of us who have tried to complile data on what we are up to in Europe statistically on just about any issue, such as me, are hardly in a position to criticise though, as that is a real nightmare!

Denmark sounds cool for TOU, but who knows what is happening across Europe, even in Germany by region?

Certainly not me!

Thomas Pedersen


I was referencing that Denmark has more registration about what people do, based on uniquely identifiable personal identification numbers than perhaps any other society in the world, apart from Iceland (or China...).

Other countries such as Germany and AFAIK USA generally have a low appetite for society-wide registration. But then you have NSA... Denmark is a very small country with a relatively high level of trust in society and 'stranger', so it has worked well for us. I doubt it would work the same way in the US... But like you said, it will probably differ by state, or even by county or parish. In Denmark the data is managed by the national grid operator, but it could just as well have been your utility supplier. As a matter of fact, my utility provider provides a similar service (within 6 months, dozens of similar apps popped up - because the data i easy to access).

Anyway, charging at the right time and place is actually not that hard, once the market can operate. Correct information is one of the vital pillars of a well-functioning market and we seem to have that in Denmark now. Btw, the 4-tier transport tarifs is a new thing introduced just this year. But prior to that, the investment was made, over the course of a few years, to install remotely readable power meters with high temporal resolution at a cost of $3-500 apiece. They just replaced the old rotary meters (that could spin the opposite way during export of solar power).

PS: I forgot to include the link before:


Interesting stuff, Thomas!

Here is TOU in the UK, where I live.
They are going slow on what to do on EV charging for the time being, with the issues arrising from the war in Ukraine, etc:

Roger Pham

The concept of day-time at-work charging with solar PV has the words "PHEV" and "PFCV" (Plug-in FCV) written all over it.
A PHEV is a Battery Electric Vehicle (BEV) for 80-90% of the total distance driven, charged daily. at home and/or at work also...Yet, it has none of the limitation of a full BEV when traveling long distances. Now, to get off petroleum, we need companies like Tesla and Solar City to provide for Solar Charging at work, during a work day with solar PV panels covering the parking lots and keeping the cars cool and the interior from degrading due to UV rays and heat. So, people without means for charging at home can still own Plug-in EV's, and people who can charge at home can double the daily commuting range on electricity.

What to do with the solar PV output during weekends and holidays when people don't go to work? We can use the excess solar energy to make Hydrogen to power Plug-in FCV (PFCV) so that they can be driven for longer distances on weekend getaway trips.
I am very enthusiastic about Renewable Energy and would like to see companies like Tesla, Solar City, Nikola, Plug-Power, move faster...much employ solar PV energy to replace petroleum as much as possible.


@Thomas, yes, it all makes sense, but it requires a level of thinking and planning that is beyond many people, especially older people, and just adds to the stress of modern life.
TOU is obviously the way to go, where you set a "charge by" time (say 7am next morning) and let the system do the rest.


I can't see TOU being any sort of hassle, especially since IMO it looks like inductive charging will be a thing.

In any case, my view is that instead of going through the energy losses involved in making hydrogen when you don't need it as such, compressed CO2 will do the job fine, at round trip efficiencies of 75% or so for periods of up to a day-ish, at way less cost than batteries:

Energy is not wasted compressing air with the nitrogen which makes up most of it doing nothing and needing cyrogenic temperatures.

For longer term hydrogen or ammonia is fine and the efficiencies acceptable when short term storage is covered by cheap CO2 compression.


How is the CO2 compressed and what is the power source for that?



We discuss it quite a bit here:

That got a bit mixed up with more sophisticated systems for underground storage and what not, and even with compressed air, where you need very low temperatures.

You don't for CO2 in a closed loop system, which simply uses an inflatable dome for the gas, then liquifies it.

And it is up and running in Sicily, getting full testing for series production.

And they use industry standard components throughout.

One of many videos here, giving much fuller details:


Sorry, it is Sardinia, not Sicily.

Here is the one demo they have up and running:

Workplace solar and charging should certainly be deployed more widely, it is mainly a function of incentives and financing.

Home solar seems to be misunderstood. My home energy use is not zero when I am at work, and by heating and cooling before the sun goes down, I can bank/shift a lot of that capacity into the early evening hours.

Batteries, some of which like Tesla Powerwall are overpriced, but others not too expensive. At an affordable cost, I can keep the solar powered lights on until I go to sleep. The cost, including batteries, is far less than I pay for grid energy.

When I buy peak power from the grid, I pay $0.60 per kWh. When I buy solar, it’s a wash per kWh including finance charges, for the first 5 years, and then free after that, likely for the next 25 years. (I could also think about it as $0.05 per kWH for the life of the system, including maintenance).

When I buy solar, my rate is flat, never changes. Stays low. I get net metering, so even if I plug in across town during the day, my charging cost is offset by my
home power plant earnings.

Utility scale solar is far less expensive for the utility to install than it is for me to install solar on my roof.

But I am still paying the retail utility rate, not the cheaper rate they pay to install solar.


@electric car insider:

You make some good and fair points.

The thiing about any discussion about renewables is that, just like renewables themselves, they are heavily dependent on when and where, especially when you throw all sorts of different regulatory regimes, subsidies, mandates, hidden subsidies in the form of not making fossil fuel output pay for the damage it does, and so on and on, which is why I am so picky about generalisations.

Almost anywhere in the continental US can now be run on renewables, often very locally based as well.

Germane to the present discussion is that traditionally renewables and low carbon energy were expensive and scarce, and the discussion tends to be working from that assumed basis.

Cheap and plentiful renewables mean that options are very different, so in the case of how you do storage, priorities change, or should do to be cost effective.

So for instance batteries can have a high efficiency for the sort of time periods we are considering, up to 24 hours.

But if renewables are cheap enough, then it makes sense not to go for expensive storage, but to go cheap, even if that is not as efficient, especially since unlike fossil fuel production excess renewables are not going to do much harm at all.

Energy Dome technology looks to me as though it can be very cheap, way cheaper than certainly lithium ion batteries, and probably cheaper than any battery likely to be available for mass deployment for at least a considerable time.

And there are options with CO2 storage to increase the efficiency of that too, but I doubt that would be competitive either.

So to me it seems probable, subject of course to the experience we are getting right now, that this tech can be rolled out really fast, with 'good enough' efficiency considering the low and falling cost of renewables.

I’d love to see Energy Dome succeed and make long term storage of renewables inexpensive and mass scale.

The most likely scenario I see is an “all of the above” approach, where well financed individuals build LEED net zero houses (including transportation fuel) and large scale public works projects (of many types) provide zero and low emission solutions to the community.

None of these are in opposition to each other. If you can afford to capitalize your own zero emission energy solution, go for it. Not just for the benefit of yourself, but for every human that comes after you that can use that facility.

Also support every variation of public works that decrease the particulates and other emissions that diminish your health and well being. And that of every human that comes after you.

I agree, Davemart, that these solutions need not be optimally efficient if they solve the problem and are closer effective. At the end of the day, the market decides which technologies hit the mark. Regulators put up guard rails and set the rules, but the market forces usually prevail in the long run.


Hi eci.

The market 'kinda' decides, but only in the context of the legislative framework operating.

So for instance if they are hitting you at a high rate for any draw from the grid, it may make sense to pay a premium to have batteries in the house.

In fact, moving electricity long distances and the consequent need for transformers and what not is where it gets expensive, and as far as I can see, Energy Dome would enable local storage, just like the town gas installations of my youth, expanding and contracting according to demand.

Particularly useful perhaps to enable rapid charging of BEVs, with its substantial grid loads.

The regulatory regime affects the practical costs, not the underlying ones, and I would have thought Energy Dome likely to be cheaper than lithium ion batteries where the regulatory regime does not disguise the costs.

In any case, the battle between different technologies should not be allowed to obscure the fact that are now starting to get a number of attractive options to decarbonise at good cost.

Northern Europe and Japan are outliers, with cold dark winters making them expensive to run on renewables all the year.

Hydrides can do it, and are running for the purpose, but the cost is currently high.

For areas like the continental USA, it is pretty well cracked though.

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