Do what's good for the environment or do what's good for me?

[GregTR]

Here is my predicament:

I am generating copious amount of excess solar during the day currently which I just dump on the grid for peanuts ($0.03/kWh). But I get absolutely free electricity at night from my REP.

Should I charge my EV during the day or during the night? From a financial standpoint the smart move is to charge at night and get as much as possible for the solar that I put on the grid (mind you I can only get up to net zero balance I can never earn more than what I spend on electricity). However I think the environmental move is to charge my EV during the day from sunshine.

I already threw around the idea of doing some bitcoin mining at night with the free electricity but my son already vetoed that idea on the basis of it killing the world...

 

[chrisski]

IMO, in your case the market drives the best use so do what’s cheaper.

 

[robby]

It goes against my core beliefs to not do whats best for the environment when I can.
I have been an avid Scuba Diver for 40 years and I have watched this planet go down the shiter over the last two decades and it honestly worries me about what will be left for my children. Do what's best for your children's future. It's always nice to see people like you who still consider the environment over the almighty buck.

 

[Rednecktek]

OK, so this is really more of a behavioral question than a technical one and as much as your question sounds like "Which is better for the environment?" you should think of it as "Is it worth the extra cost to help the environment?"

So, there's really only 1 way to get a clear answer. Your October billing cycle should start up any time now, check your bill and see when that is. Then for the next month charge the car via solar for a month and see what your new power bill is for the credits you're NOT putting back into the grid. When you get your bill for the new nightly power usage look at it and ask "Is paying this bill cost effective enough that it's worth it?'

If your bill has gone from $10/mo to $30/mo then the extra $20 would be a drop in the bucket. If on the other hand it goes from $10/mo to $500/mo then it would be worth reinvestigating better options be it a behavioral change or more panels or a complete EV-Only charging system independent from your grid connection or a giant hamster wheel and some rowdy neighborhood children.

Winter is probably going to make a difference so you might want to re-run the experiment a couple times for a better feel.

Then of course come back here and tell us how it all goes!

 

[sollap]

Here's a wild thought. Is there any chance that the energy available at night from your REP is environmentally cleaner than their daytime energy? There may be plant load/efficiency curves to consider, as well as the use of any add-on facilities used only during high-demand. If such a variable environmental impact exists, then by charging at night you consume the cleanest energy available from the REP, while the clean energy you put on the grid during the day offsets the demand and use of the lesser clean power by others.

 

[Shimmy]

The best solution environmentally is likely to charge at night, especially if you are in Texas. You will offset less environmentally friendly generation during the day, and some portion of your night consumption is going to be wind power (the rest is going to tend to be lower emissions base-load power).

(for anyone from Texas) Does ERCOT do a real-time breakdown of grid energy by source like California does?

 

[ianganderton]

My vote is for charging the car at night

Peak demand is during the day and always will be. Contributing as much clean power to the grid as possible during the day reduces the need for dirtier power

Using as much required power at night makes use of the excess that is available and would otherwise go to waste thereby flattening the demand curve.

 

[noenegdod]

I know nothing about your grid, its power supply and the billing but where I am there is a base load that the coal fired plants operate at. If the consumption is lower than that base load, the energy is dumped but the boiler firing rate remains the same. If your getting actually free power at night it may be for this reason and not using it may in fact be wasteful. Again, IDK, just a possibility to look into.

 

[John Frum]

REP

Is that "Renewable Electricity Program"?

 

[GregTR]

Is that "Renewable Electricity Program"?

Retail Electricity Provider, the company that puts power on the grid for my usage. In Texas we have a free market where I can choose who I want to buy energy from. The REP I'm buying from is offering it for free at night and charges a lot more ($0.29/kWh) than the cheapest fixed price ($0.13/kWh) I could buy today. The plan I'm on is touted as 100% green energy but in the fine print they state that they achieve it by buying carbon offsets which, as we all know, is not exactly the same thing.

The best solution environmentally is likely to charge at night, especially if you are in Texas. You will offset less environmentally friendly generation during the day, and some portion of your night consumption is going to be wind power (the rest is going to tend to be lower emissions base-load power).

(for anyone from Texas) Does ERCOT do a real-time breakdown of grid energy by source like California does?

They do: https://www.ercot.com/gridinfo/generation
Look under "Fuel Mix". They provide downloadable 15 minute detailed data since 2007.

Here is 8/1/22:

 

[GregTR]

Thanks for all the feedback, it appears there is no easy right answer here with the amount of unknowns.

From a strictly conservation of energy perspective the best bet is always going to be to consume where it's made so it's probably most environmentally friendly to charge my EV on PV during the day.

We're talking $0.03/kWh difference here so about $0.30/day one way or another, about $10 worth of electricity in a month, hardly a difference maker.

 

[fromport]

Should I charge my EV during the day or during the night? From a financial standpoint the smart move is to charge at night and get as much as possible for the solar that I put on the grid (mind you I can only get up to net zero balance I can never earn more than what I spend on electricity). However I think the environmental move is to charge my EV during the day from sunshine.

I already threw around the idea of doing some bitcoin mining at night with the free electricity but my son already vetoed that idea on the basis of it killing the world...

For me it is a bit different.
No free electricity. All the power I pull back from the grid costs me at least $0.02/kWh.
I try and charge on the PV available during the day.
When there is not enough available and I need a full charge the next morning, I also charge at night.

For me it is combination where I prefer environment over my own financial gain but if needed i mix & match

 

[Hedges]

During the day, power you dump into the grid for your neighbor to use reduces current carried by wires to the neighborhood.
Power lost in wires and transformers goes as square of the current.
You are probably reducing losses by reducing that heavier current during the day, and drawing lower current at night.


Financials are used as a signaling mechanism to request you to do something. But rates are set by committees with agendas, often serve utilities financial interests not the environment. It is likely not far off to assume everything is a lie, including claims of what is good for the environment.

In California, PV peaks middle of the day, and demand mid afternoon (leaving the "Duck's Back Curve", which is simply all consumption minus only PV production). Possibly charging middle of the day would be good, unless that results in more fossil fuel consumption (which the utility likes because they purchase and resell profitably.)

If as people suggested, $0.00/kWh at night means the power is otherwise burned off in a dump load, that is the time to charge.

 

[GregTR]

Interesting point about the power I dump during the day only has to go next door, it's not like it has to travel all the way back to my REP. I didn't think about it that way. This kind of makes the "use it where you make it" argument completely moot and night time consumption at lower currents might even be better.

As I said, I'm keenly aware that just because my REP calls it green it doesn't mean it's 100% renewable. And just because something is cheaper doesn't mean there are no externalized costs that are not part of the price.

I don't think the $0.00/kWh at night means dump load, it just means "clever TOU pricing scheme". They charge a lot during the day and nothing at night with the average per kWh being substantially high once the night vs. day ratio sorts itself out. For solar users with battery the scheme doesn't work and as long as they don't lose too much on one-off users like me they will keep offering the plan for years to come where my "free" is subsidized by other people essentially. On some level it almost feels wrong but on the other hand I love doing all kinds of arbitrage where I feel like I am beating the house odds.

 

[fromport]

If as people suggested, $0.00/kWh at night means the power is otherwise burned off in a dump load, that is the time to charge.

"In the state of Texas, year to date, they have consumed some 22.9 million tons of coal, polluting the planet, making conditions worse, impacting climate, exacerbating the very conditions they're trying to mitigate in terms of their energy reliability," Newsom said.
California, by contrast, had consumed just 18,000 tons of coal during that time period, Newsom added.

*Update*
Sensus 2021
Texas 29 M people
California 39 M people

Don't charge at night in TX

 

[Lilikoi_Heavy_Industries]

Seems like getting off the TX power grid entirely would be the most responsible thing you could do if you don't want to be associated with those clowns who would go out of their way to pollute, the people running TX.

Oh that would cost you more? So it's not about the planet.

 

[GregTR]

Seems like getting off the TX power grid entirely would be the most responsible thing you could do if you don't want to be associated with those clowns who would go out of their way to pollute, the people running TX.

Oh that would cost you more? So it's not about the planet.

I appreciate the jab, duly noted... Seems like my soul has a price and it's about 100 kWh of batteries and 14 kW of PV panels and micro inverters.

I also travel across the ocean at least once a year via jet, I hope you can forgive me for that too.

 

[Lilikoi_Heavy_Industries]

I appreciate the jab, duly noted... Seems like my soul has a price and it's about 100 kWh of batteries and 14 kW of PV panels and micro inverters.

I also travel across the ocean at least once a year via jet, I hope you can forgive me for that too.

If you send them any money, you're a part of the problem. I don't think you can seriously refute that.

And no, you don't need to buy all that stuff, you could just use less energy. Sometimes you have to relocate to make that possible.

The thing is, I'm not placing blame, so you're confused when you ask for forgiveness. It's you that started claiming that something about your lifestyle is doing "whats good for the environment". It looks like you have two options: bad or worse.

And yes, I'm just pointing at that the earth would have a smaller biological load to process (you know, like a fish tank) if there were less of all of us, me included.

You're the one that made it about doing what's good for the environment sir I'll be over here burning a pile of tires for fun.

 

[wattmatters]

Does ERCOT do a real-time breakdown of grid energy by source like California does?

You can see ERCOT CO2 emissions intensity here:

Live 24/7 CO₂ emissions of electricity consumption

Electricity Maps is a live 24/7 visualization of where your electricity comes from and how much CO2 was emitted to produce it.

app.electricitymaps.com

It's a fossil heavy generation region (gas mostly), and is fossil heavy at all times of day and night.
Over past 12 months only 30% of generation is low carbon (21% renewable, 9% nuclear). Rest is gas and some coal.

 

[GregTR]

If you send them any money, you're a part of the problem. I don't think you can seriously refute that.

And no, you don't need to buy all that stuff, you could just use less energy. Sometimes you have to relocate to make that possible.

The thing is, I'm not placing blame, so you're confused when you ask for forgiveness. It's you that started claiming that something about your lifestyle is doing "whats good for the environment". It looks like you have two options: bad or worse.

And yes, I'm just pointing at that the earth would have a smaller biological load to process (you know, like a fish tank) if there were less of all of us, me included.

You're the one that made it about doing what's good for the environment sir I'll be over here burning a pile of tires for fun.

Trust me, I don't need your permission to do as I please nor do I need your approval to use as much or as little of our resources as I see fit.

I simply asked which of the two, charging at night or charging during the day, make a better environmental sense as the economic and convenience impact on my life were inconsequential.

I don't need any further advice about how I could make a much bigger impact of reducing my carbon footprint by moving to another location and/or using less energy. That is beyond the scope of the question and your virtue signal is lit way brighter than mine at this point. I'm sure you're a much better person for it, good for you!

 

[GregTR]

You can see ERCOT CO2 emissions intensity here:

Live 24/7 CO₂ emissions of electricity consumption

Electricity Maps is a live 24/7 visualization of where your electricity comes from and how much CO2 was emitted to produce it.

app.electricitymaps.com

It's a fossil heavy generation region (gas mostly), and is fossil heavy at all times of day and night.
Over past 12 months only 30% of generation is low carbon (21% renewable, 9% nuclear). Rest is gas and some coal.

Thanks for that map, it's truly fascinating! While most of it is not actionable information is surely appreciated!

 

[wattmatters]

While most of it is not actionable information is surely appreciated!

In the context of understanding the CO2 emission intensity at different times of day in your region, this and other similar sources of data provided by your utility, will help answer your fundamental question.

But it most certainly is actionable.

CO2 Signal provides an API (as probably do some other similar sources), and hence it is possible to design automations which choose the most carbon friendly times to consume. You can have your cake and eat it in this sense - IOW some days it might be better to charge your EV at night, while at other times it might be better to do it during the day.

We already have systems here with one retailer who passes through wholesale prices which can use both emissions and price data to choose when to charge/discharge batteries and they also have an API which can be used for control of other loads, such as heating/cooling, EVs, hot water systems etc.

Where I am emissions intensity is pretty much always far lower during the middle of the day than in the evening or overnight. About half. So from an environmental POV where I am it is far preferable to shift discretionary loads to the daytime than to consume at night. This is even more the case than the straight grid generation emissions data suggests because curtailment is often applied to renewable energy sources here during the daytime. It's a little like off-grid PV systems, use it or lose it. It's one of the main reasons I added a smart solar PV diverter for my hot water system. It now preferentially uses my grid-tied solar PV rather than the coal fired off-peak power overnight.

I suspect in the ERCOT region that on average the daytime grid is a little less emissions intensive than at night, but probably not my much. Mainly because of the relatively low level of solar PV in the grid supply.

 

[Ampster]

Mainly because of the relatively low level of solar PV in the grid supply.

Texas has huge wind energy capacity and the probably affects the statistic more than solar.

 

[Hedges]

I appreciate the jab, duly noted... Seems like my soul has a price and it's about 100 kWh of batteries and 14 kW of PV panels and micro inverters.

I also travel across the ocean at least once a year via jet, I hope you can forgive me for that too.

That depends ... are you the only one on board, who's not in the cockpit?

 

[GregTR]

In the context of understanding the CO2 emission intensity at different times of day in your region, this and other similar sources of data provided by your utility, will help answer your fundamental question.

But it most certainly is actionable.

CO2 Signal provides an API (as probably do some other similar sources), and hence it is possible to design automations which choose the most carbon friendly times to consume. You can have your cake and eat it in this sense - IOW some days it might be better to charge your EV at night, while at other times it might be better to do it during the day.

We already have systems here with one retailer who passes through wholesale prices which can use both emissions and price data to choose when to charge/discharge batteries and they also have an API which can be used for control of other loads, such as heating/cooling, EVs, hot water systems etc.

Where I am emissions intensity is pretty much always far lower during the middle of the day than in the evening or overnight. About half. So from an environmental POV where I am it is far preferable to shift discretionary loads to the daytime than to consume at night. This is even more the case than the straight grid generation emissions data suggests because curtailment is often applied to renewable energy sources here during the daytime. It's a little like off-grid PV systems, use it or lose it. It's one of the main reasons I added a smart solar PV diverter for my hot water system. It now preferentially uses my grid-tied solar PV rather than the coal fired off-peak power overnight.

I suspect in the ERCOT region that on average the daytime grid is a little less emissions intensive than at night, but probably not my much. Mainly because of the relatively low level of solar PV in the grid supply.

I meant the data on that website is vast, ie. how green any given country is at any given time, and while it's fascinating, it's not actionable.

Sure, looking at the ERCOT specific data on an hourly basis shows me that the most green power is during the day and the most polluting is during the 7pm duck curve peak hours. But seeing this data, while nice is not that actionable either. In the aggregate I think daytime charging looks the best but I can assure you I won't be building automation around the pollution matrix of the Texas grid.

The other problem is that once I make a decision at night not to charge I have to charge during the day so I would have to make decisions on predictions rather than actuals as I am not a prophet seeing into what the future would bring.

Based on this discussion and looking at the data the difference in carbon impact is marginal between daytime and night time charging. But somehow I sleep better at night if I charged the car from solar, it was definitely 100% renewable that I personally used even if this does not make rational sense.