Researchers map where solar energy delivers the biggest climate payoff
51 comments
·August 1, 2025sabakhoj
kumarvvr
US Produced about 4.8 Billion Metric Tons of CO2 in 2024 ( https://www.statista.com/statistics/183943/us-carbon-dioxide... )
The savings is minuscule. But important nonetheless. It just goes on to show how much more solar is required.
bawolff
Given that solar power is 4% of electricity generation, a 15% increase is like 0.5% percentage points in total. Roughly 30% of co2 is from electricity generation, the numbers all seem to make sense.
If you replace 0.5% of things that emit carbon with non-carbon sources it reduces carbon emissions by 0.5%.
Cheezmeister
I mean it's five basis points, it ain't nothin.
Put another way, if I could grease the right palms to shave commensurate minuscule savings off of the budget of ICE, it'd pay off my mortgage. Twentyfold.
Back to greenhouse gases, I'm no climatologist, but isn't it plausible the difference could, for instance, make or break one catastrophic wildfire across the western seaboard of North America?
Beware of statistic thinking in a stochastic world.
hawk_
Fifty basis points.
aaron695
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spwa4
[flagged]
adrianN
Solar is cheaper than oil, and oil is essentially never used for electricity.
gnabgib
Of the world's power 35% is coal (solid oil), 20% Gas/Natural Gas (gaseous oil), 3% oil (Wikipedia def'n).. 58% of our power is oil https://en.wikipedia.org/wiki/List_of_countries_by_electrici...
Are you being particular about your definition of oil?
Light Oil (C4-C12 aka "Gasoline"(NA) "Petrol"(EU)) is used for personal generation and backup power systems.
Heavy oil (C9-C25 aka "Diesel") is regularly used for electricity, extensively used for backup power systems.
squigz
I don't think Jevon's Paradox is applicable here? This is about solar becoming more efficient.
In any case, if the argument is that oil is going to be pumped regardless of how much it's actually used, can we not just save it for a rainy day, so to speak?
colechristensen
The reason this is a stupid argument is that solar power is significantly cheaper than fossil fuel power almost everywhere. And not in a "calculating all of the global impacts" way, in the very direct, greedy, "I want the cheapest electricity possible" way. "Whatabout"s with storage and time of day, etc. aren't necessary, battery tech is cheap and solar production is so cheap you can do inefficient things with it (panels at non-ideal angles to get more power at off peak hours) and still come out ahead.
I really doubt China is installing solar at insane rates to be nice to the world.
putinapologist
[dead]
liquidise
Direct study link (with associated diagrams): https://www.science.org/doi/10.1126/sciadv.adq5660
csense
The study compares a percentage increase of solar power against an absolute decrease of CO2 emissions.
This seems like questionable reasoning to me. If California has 100 MW of solar power for every 10 MW in Indiana, a 10% increase in solar will show up as 10x more CO2 savings for California just because it has a larger installed base.
To me the relevant question is the relative dirtiness of the nonrenewables being replaced, and the relative cost and effectiveness of solar. IMHO the data ought to be normalized to a per-MW-installed-rating basis.
I wish the study went like this (all the following numbers are completely made up, based on nothing more than the fertile imagination of an HN commentator mildly annoyed by the study's questionable numeracy):
- In California, clouds / latitude / etc. mean a panel's only usable 10/24 hours on average per day
- In Indiana, the geography's less ideal, so clouds / latitude / etc. make it usable 8/24 hours on an average day
- In California, it would be replacing a super-clean natural gas plant installed in 2008 that has expensive high-tech emissions control devices required by the super-strict California environmental regulations and emits 0.4 tons of CO2 per MWH.
- In Indiana, there was no money or political will for modern power plants or strict environmental regulations, so the solar panel would be replacing a smoke belching coal plant from the previous millenium that emits 1.2 tons of CO2 per MWH.
- In California, labor for >1 MW solar installations costs $0.20 / W, costs are inflated by high CoL / taxes and business unfriendly regulations but there are lots of firms with experience who can install quickly.
- In Indiana, labor for >1 MW solar installations is $0.15 / W, they pay a lot less and don't have as much red tape, which slightly outweighs the fact installers don't have much experience and bumble around being slow and making expensive mistakes.
- Your per-watt cost is $0.20 / (10/24) = $0.48 in California but $0.15 / (8/24) = $0.45 in Indiana (which is also your per-MW cost in millions).
- Your daily emissions reduction is 0.4 x 10 = 4.0 tons for California and 1.2 x 8 = 9.6 tons emissions reduction for Indiana.
- Therefore every $1M spent in California buys 4.0 / $0.48 = 8.3 tons / day of emissions reduction and every $1M spent in Indiana buys 9.6 / .45 = 21.3 tons / day of emissions reduction.
If you care about efficiently spending money to reduce emissions, in this example (using made-up numbers) Indiana is the low-hanging fruit, investments there are better by a factor of 21.3 / 8.3 ~ 2.6.
But the way the study's written, if we assume solar is currently 2000 MW for California and 200 MW for Indiana, its calculations would suggest a 10% increase in California (200 MW) would save 200 x 4.0 = 800 tons and a 10% increase in Indiana would save 20 x 9.6 = 192 tons.
This is very misleading.
If you don't think about the units and just look at the numbers, you might be tempted to conclude the study's telling you that California's emissions reduction rating is 800 and Indiana's rating is 192, so if you care about CO2 reduction every dollar of investment is a factor of 4 as effective in California -- when in reality, with these numbers every dollar is actually a factor of 2.6 more effective in Indiana.
malfist
There is no "super clean natural gas plant" you're still burning a nonrenewable hydrocarbon and letting its carbon go into the atmosphere
null
spwa4
> The study compares a percentage increase of solar power against an absolute decrease of CO2 emissions.
local CO2 emissions. This has not affected pumping of oil, and since we aren't even able to store much oil, that means it's getting burned. That makes it clear the global effect must be very close to zero. And for CO2, only global matters.
two_handfuls
You're essentially arguing that reducing demand won't reduce supply. It may not do so immediately, but certainly over time it will.
For example, there are oil fields that are unexploited because they would not be profitable. If demand rose, prices would rise and new wells would be opened. The reverse is also true.
smadge
California has the opportunity to be a beacon in North America for environmental and climate action e.g. by expanding solar production, finishing the CAHSR, and other projects like expanding and electrifying mass transit and commuter rail networks, but they are their own worst enemy.
oceanplexian
California has already fallen behind both Texas and Florida in new utility grade solar. As for CA-HSR, no comment. But if you don't want to wait, you can buy a ticket today and ride Florida's new high speed rail between Orlando and Miami.
drtz
The fact that Brightline can take you from Miami to Orlando is wonderful, and I'm really happy Florida is embracing more efficient, less dangerous, and less stressful forms of transportation.
But using it to make a subtle jab agains CAHSR isn't really fair -- they're two very different projects (for one of them, it's genuinely a stretch to call it "HSR") in two very different regions.
Yes, it's harder to get big projects through the red tape in California than it is in West / Panhandle Texas or Central Florida. Go take a drive through those regions and you'll quickly see some reasons why, besides just NIMBYism, Californians are a bit more protective of their landscapes. If a massive wind project were proposed across large swaths of the Texas Hillcountry, you'd see a lot more push-back.
parineum
> or one of them, it's genuinely a stretch to call it "HSR"
How fast is California's HSR?
That's both sarcasm and an actual question. It doesn't go anywhere now but I keep hearing it's speed get downgraded as they encounter the real world. Plus, the goal of LA-SF is practically abandoned and now it takes you from a place you don't want to be to a place you don't want to go.
You really can't compare the two because one exists only as a goal and the other is an accomplishment.
drtz
Also, fwiw, we've had an HSR project in the works in Texas for a couple decades now and have yet to even make a solid plan, much less break ground.
renewiltord
> But using it to make a subtle jab agains CAHSR isn't really fair -- they're two very different projects (for one of them, it's genuinely a stretch to call it "HSR") in two very different regions.
Well, CA HSR doesn't exist. It's missing the R part of the HSR. So that must be the one it's a stretch to call "HSR".
toomuchtodo
Brightline’s muni bonds have been downgraded to highly speculative. Ride while you can.
https://www.fitchratings.com/research/infrastructure-project...
https://www.bloomberg.com/news/articles/2025-07-11/florida-s... | https://archive.today/LEyBC
seszett
Brightline is a diesel train that runs 80-125 mph (130-200 kmh) though, that can hardly be called HSR. In Europe or Asia that is just called "rail".
kccqzy
That high speed rail is not electric unlike high speed rail in Europe or Japan or China. It doesn't deliver enough climate benefits.
ackfoobar
A diesel train releases orders of magnitudes less CO2 than flights though.
slt2021
modern diesel is extremely clean, and when compared to air travel, the benefits are clear, both in cost and in carbon emissions
rdtsc
GH project with a link to the data and the instructions how to process it https://github.com/NSAPH-Projects/green-energy-optimization
gsf_emergency_2
"raw data" is from EIA (a veritable rabbit hole!)
>EIA publishes hourly operational data across the United States electricity grid, including demand, net generation of electricity from various sources (such as coal, natural gas, solar), CO2 emissions, import/export to other regions, and many more. The complete details of the EIA-930 data is available here: https://www.eia.gov/electricity/gridmonitor/about. Furthermore, we obtained the solar capacities of each year and each region from EIA (https://www.eia.gov/electricity/data/state/) and had stored the information in the file solar_capacity_factor.csv. (2023-07-01)
metonymy
except there's no map!
s1mon
And "California" is a huge area. I doubt that the entire state is ideal for solar. I was hoping to see an actual map and zoom in on my neighborhood. I want to know if it makes sense to install on my house. This is zero help.
andsoitis
Verb vs noun
dmead
It's like reading an article about a painting. I think this might be the worst experience.
jtbaker
you had one job!
sophia01
When I read "map", I think "map"...
m0llusk
This kind of reasoning and technology would never have predicted the surge in popularity of patio solar in Germany.
nandomrumber
Germany electricity:
€0.3943 / kWh
That's about US$0.46 or AU$0.71 per kWh
That largely explains the surge in popularity of patio solar in Germany.
chickenbig
Germany in H2 2024 was at €0.3943 per KWh including standing charges [0], so not quite the right number when evaluating whether balcony solar is worth it.
[0] https://ec.europa.eu/eurostat/statistics-explained/index.php...
Vespasian
Just a small correction but 39cts is a pretty bad price even for Germany.
You'll typically get ~30 these days with minimal comparison.
Still expensive but a full quarter less.
null
nandomrumber
Good to know
adrianN
The important part of making it popular was changing laws to make it dead simple to install.
nandomrumber
The important part is cheap abundant energy obviates the need for the average person to have to worry about being their own electricity generator.
lorenzohess
On Mercury
searine
Funded by US taxpayers via 11 grants, predominantly from NIH with additional institutional support from Harvard University.
> The central finding is that a 15% increase in solar generation across the U.S. is associated with an annual reduction of 8.54 million metric tons (MMT) of CO2, a significant step toward national climate goals.
Whoa, that's really cool.
You can see the paper along with figures & regional breakdowns here: https://openpaper.ai/paper/share/1d0c6956-4820-4ee2-ac1e-12c...