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- Hacker News
- Hey guys, A small site that checks, every day, whether making electricity cheaper when the grid is clean would actually cut CO₂.
It reads yesterday's generation mix from ENTSO-E and the EIA, works out the carbon intensity hour by hour, and compares a normal tariff against two carbon-aware ones.
It started for Switzerland, which turned out to be a good place to start for an odd reason. Swiss electricity is already very clean — about 34 gCO₂/kWh — and yet it's one of the best grids in the set at 2.4%, because it imports from dirtier neighbours and its carbon intensity swings through the day. Louisville, at 741 g/kWh, gets 0.01%: it burns coal at the same rate around the clock, so there's no cleaner hour to move into.
Across 38 grids, the correlation between the saving and how dirty a grid is comes out slightly negative. With how much it varies, it's 0.91. Being dirty doesn't help at all — being uneven is the whole thing.
Fair warning: the demand response is a model rather than measured behaviour, and it uses average carbon intensity, not marginal. Happy to hear your thoughts.
by High-Five - How are you modelling how demand changes in response to price changes?by floodle
- Is it assumed that the total consumption remains the same (i.e there is an increase in consumption in clean energy when there is a decrease in less clean ones)?
Otherwise, there would be an obvious solution which is to increase the price all the time to reduce demand and thus reduce CO2 consumption, but it is impractical politically.
by addag - Proportional decrease is not as useful in a climate change sense than actual decrease in co2 emissions. A grid that is highly sustainable with lots of wind and solar, but fossil peaker plants will have a lot more potential co2 savings in this model. It essentially makes dirty grids look cleaner.by Maxion
- Man, I am so tired of reading slop.by calinet6
- At this point I can tell fairly reliably from titles alone, "measured daily on 38 grids" is not the kind of thing a human would write in this context.by Retr0id
- I’ve been thinking about this the CO₂ usage could be part of the price. I had toyed with having a two dimensional price, the price alongside the CO₂ usage, but I guess that way madness lies.by zeristor
- On the long-term, the French option of just running a low-carbon grid remains the obvious solution.by maelito
- Yep. Poisoning the planet with nuclear wast for a million years. 40,000 generations of our children will be happy and thankful.by Archelaos
- France has been offering lower prices at night to make the most of their nuclear since the 1960s.
Australia used similar tech to make the most of baseload coal overnight since the 1950s.
It's just a good idea, and should be used to get cheaper cleaner power in grids today too.
by ZeroGravitas - Not really. Nuclear power requires massive subsidies. In Germany, the "De Height" wind farm was completed in August. Sixty-four 15-MW turbines generate about 4 TWh of electricity annually, which is sold entirely on the open market without any EEG funding.
The market for baseload electricity has disappeared in Germany, as renewables push the residual load to zero or below for almost the entire year:
https://www.energy-charts.info/charts/power/chart.htm?c=DE&l...
The base load is an imaginary line passing through the troughs of the residual load curve.
by boshomi - Spending 19 billion € over 18 years to build 1.65GW Flamanville 3 is not quite obvious to me.
https://en.wikipedia.org/wiki/EPR_(nuclear_reactor)#Flamanvi...
Edit: compare this with China: they added 315 GW of Solar capacity in a single year (2025; see page 34 of the PDF).
https://www.irena.org/Publications/2026/Mar/Renewable-capaci...
(You can't compare nameplate capacity directly, but it can be safely assumed that 2 orders of magnitude more is ... actually more)
by the_why_of_y - Sure, but I don't think the two ideas are really in conflict. A low-carbon grid should absolutely be the end goal, but even a mostly clean grid has hours that are cleaner than othersby HexPhantom
- The EU does that since the emissions are taxed via the EU ETS and it just results in the most expensive electricity in the world.by mono442
- The idea is interesting but unfortunately most of the people don't know the electricity price even now without this mechanism. This should be displayed on top of every washing machine everywhere to make it worksby flaburgan
- Dryer? Are washing machines expensive to run?
- My electricity provider has a near real-time graph of energy generation by source (wind, solar, coal, etc.) and I use this during off-peak times to decide when to use or avoid certain loads. For example I love charging batteries when solar is producing more energy than is being used by customers.
For a global map, check out Electricity Maps:
by Panino - This is kind of a stupid preposition. the cheapest hour should be the cheapest with carbon externalities priced in. There are lots of times where it is both logical and good for the cheapeat hour to not be the lowest carbon (i.e minimum run times on foasil fuel plantspushing should hours very cheap because they are needed for the peak hours or forecast renewable drop off.) If the market isnt pricing the carbon externalities that is a seperate issue.
further the grid price only represents variable costs, congestion, and bidding strategies of gen to try and also recoup fixed costs and make a profit. This may translate to cheaper when lower carbon because variable cost is zero for many renewables but making it explicitly happen breaks the market price finding mexhanism and is probably an even larger aubsidy to renewables, which in itself is stupid vs just pricing the carbon externalities and letting the market decide.
- In my country (for people with a so called "dynamic pricing" contract) the price of electricity already drops significantly when we have a load of green energy (wind, solar). I guess this is just a side effect of not having a well-balanced grid. But still that's already kind of a CO2-based pricing - although not directlyby jaapz
- Mostly yes, but it works the other direction as well: a fossil power station may not want to completely shut down because it expects more demand later in the day, and offer a few hours of low cost electricity to stay in the merit order.by Zeebrommer
- This is what makes me wonder how much additional benefit an explicit carbon signal actually buys you over normal dynamic pricingby HexPhantom
- The harder question is probably whether dynamic pricing changes behavior without mostly becoming a penalty for people who have less flexibility in when they use electricityby HexPhantom
- I've long thought there should be a standard mechanism for back pressure for loads that can defer their usage.
For example dishwashers, overnight battery charging, car charging, etc should be able to receive scheduling data from the grid to determine the best time to run.
Users could of course be given a choice whether to use grid scheduling in exchange for lower prices or not.
by zacmps - There should be a penalty for having less flexibility in consuming electricity. That’s how the market incentivizes us to figure out how to be flexible in our consumption.
We should probably also subsidize the conversion, for people who look at the incentives, want to become more flexible, but don’t have the money.
And we might have to handle some special cases—maybe hospitals, for example—where reliable power is an important social good. But these should be rare.
by bee_rider - Mine is just flat pricing but I do try to align it.
UK has big variations in carbon intensity depending on how solar & wind is doing, so easy enough to make a small effort to align discretionary things like washing machine with that
There is also a very nice dashboard for UK grid that shows clearly what's going on at any point in time.
by Havoc - That dashboard is great. The UK is probably the best case for this in Europe. Moving the washing machine is basically what my model assumes, except it assumes everyone does it every day. NESO publishes a carbon intensity API, so the UK is an easy one to add. On the list.by High-Five
- There is also another website which offers more information on generation plants (planned and built) [0].by tentacleuno
- Here is an analysis from Germany: Quarter-hourly spot prices compared to the share of renewable energy generation in total generation. A higher share of renewables puts massive downward pressure on the spot market electricity price.
https://www.energy-charts.info/charts/price_scatter/chart.ht...
Since price elasticity for electricity is very high, the market cap decreases by approximately €150,000 for every additional GWh of renewable energy production. A single additional offshore wind turbine with an annual output of 60 GWh reduces the combined revenue of all electricity producers by about €9 million per year that it is in operation.
Blocking wind power and solar projects only serves to secure the profits of monopolists and oligopolists in the electricity market, but causes massive harm to the economy.
by boshomi - It'd be really great if wind turbines across Germany were producing at uncorrelated times.
Let's look at the wind right now: uniform wind across Germany:
https://earth.nullschool.net/#2026/09/04/1200Z/wind/surface/...
Let's look at the wind earlier: uniformly no wind across Germany:
https://earth.nullschool.net/#2026/09/02/0000Z/wind/surface/...
Hmmmm.
by BenoitP - This is interesting, but now explain why Germany has both the highest electricity prices in Europe as well as a relatively high CO2 footprint from electricity? Germany is buying not only nuclear but also coal energy from neighbouring countries.
Will this be fixed at some point or is the German model not actually as good as you imply?
by jstimpfle