How do I find out what sort of power plants provide my specific area?

I recently heard a radio news factoid that half of Illinois’ electricity generation comes form nuclear power. I also heard in the past that Illinois gets nearly half of its electricity from coal. These numbers I can confirm here which shows both at about 48% with natural gas and wind filling the scraps.

But how would I go about getting more granular data than that? If I wanted to find out which sort of plant fed my house’s or businesses its base power, where would I look? (Near West of Chicago, just for an example :))


Call or write to your power provider and ask. Or just visit their website. Our power provider provided this information to us in a leaflet when we signed up with them; I suppose the same information is available somewhere on their website.

There’s no way to find out specifically which plant is powering your house at a particular time. Electricity is bought and sold like a commodity and so it will vary from day to day which plant it comes from. I work for a power company that services six states in the Pacific Northwest, but we sell power to southern California and as far away as Arizona. CA and AZ also buy power from other states and generate some of their own.

ETA: My local power company sells hydroelectric and wind power for a few more cents per kilowatt-hour. The large print implies that paying 3¢ more per KwH you’ll get power specifically from windmills and such, but in reality it’s just to help pay for more wind turbines to be built, and the extra power you pay for is added into the aggregate power supply. In another irony, I can’t actually be a paying customer for the power company I work for since another company already has the market here.

That depends on where you’re living. Some power plants are not connected to any others. In such cases it’s trivial to find out which plant is powering your house at a particular time.

Looks like the data from the OP came straight from EIA , which is a reliable source. They have tons of good info, so I’d start there.

That said there is the caveat that all energy goes into the grid and is indistinguishable from the energy from all other plants connected, so it’s not like the electrons from a particular plant get directed to your house. It’s like a sink with a couple hundred faucets emptying into it.

Table 5. Electric Power Industry Generation by Primary Energy Source, 1990 Through 2008 (Megawatthours)


Energy Source 2008 MWHs Percentage Share

Total Electric Industry 199,475,178 100.0%
Coal 96,644,038 48.4%
Petroleum 142,728 0.1%
Natural Gas 4,259,870 2.1%
Other Gases 53,874 *
Nuclear 95,151,694 47.7%
Hydroelectric 138,549 0.1%
Other Renewables 3,034,977 1.5%
Other 49,448 *

I’m not sure what you mean by this. Commercial power plants, to my knowledge, are all connected to the grid. There doesn’t have to be a direct connection from plant to plant, any more than my computer has to be directly connected to yours as long as we’re both connected to the internet. All houses are connected to the grid, not to a specific plant. (Businesses that maintain their own power plants can be said to have direct connections, but it would be odd for these not to be connected to the grid as well.)

EvilTOJ is correct. Demand changes every second of every day. There is some slack in the system to account for this but if the demand changes by more than a few percent a central control station will ask for plants to be powered on (or off) and shunt power to wherever is needed, pretty much on a minute by minute basis. You cannot know which specific plants are providing the power at any given time.

“The” grid? What grid? There are several grids. If the location listed in your profile is correct, then my grid is almost certainly not connected to yours. And some grids are so small that they have only one power plant.

Ummmm… no. All the various electrical grids in North America are interconnected.

OK, please provide a cite for your claim that my grid is in London connected to the OP’s in Illinois.

No they aren’t. Even your own cites contradict you. Did you read them?

While it is true that the vast number of public North American grids are connected, there are exceptions in remote locations. The Chelan County PUD in Washington State operates a small grid at the north end of Lake Chelan that has no interconnects (link).

As those links show there are three major grids in the U.S., the eastern, the western, and Texas. There are connections among the three, although it is difficult to move any sizable amount of power across them, so they are in practice considered as three separate grids. Technically speaking, however, the three grids are connected.

Here’s a good map of the transmission lines.

If you’re saying that we’re assuming that the OP is talking about the U.S., from the mere fact that he referred to Illinois, then you’re correct. If you say your grid isn’t connected to ours because you’re in London, England rather than London, Arizona or London, Ohio, then you’re also correct. If you’re in London, Ontario, then you’re wrong because the U.S. and Canadian grids are connected. I know huge amounts of hydro power flow down from Quebec and Ontario and I think that a similar situation exists on the west coast.

I appreciate SuperAbe making an actual contribution to this thread to point out there some tiny local anomalies still exist. They are tiny and they are local, though. For most practical purposes, and for 99.9% of Americans and American power plants, they are interconnected through the grid.

I’m not even sure that this statement is true, unless you’re using the term “North America” in a very narrow sense (i.e., excluding most islands, Central America, and the Caribbean). Quite possibly every major Caribbean island has its own independent power grid. Newfoundland certainly does, as do the islands of Nunavut. Given the number of such islands, there are probably more independent than connected grids. We’re not talking only about insignificant backwaters, here; these independent grids collectively serve tens of millions of people on huge geographical areas.

This is one of the big advantages of the natural gas plants that provide a couple percent of the OP’s power, incidentally: Unlike a coal or nuclear plant that can take hours to power up or down, a natural gas plant can power up almost immediately, to react to small unexpected fluctuations in demand.

That’s not true of all gas-fired plant. When you refer to plant that can power up almost immediately (within minutes), you are thinking of open-cycle gas turbine peaking units.

Combined cycle or gas-fired boiler units can take hours to start from cold.

However a gas-fired plant that is already running (but not at full load) can deliver additional power quickly. The same is true of a coal-fired plant. This is called “spinning reserve”.

Thank you all for the effort but I am still confused.

My provider is ComEd, a division of Exelon. According toits website they are 93% nuclear, and according this Wikipedia page the coal plants are all owned by other companies.

And surely it makes sense that power generation is going to be provided in a way that minimizes transmission losses when possible, even if it is to some degree fungible using interconnected grids. These are not HVDC lines after all. Shortfalls will be imported when needed and excess baseline production exported when possible but it seems unlikely that such is done when closer generation sources are more matched to local demands.

Given that I pay my bill to Exelon, can I conclude that I am likely getting most of my power from a nuclear plant, or should I conclude that Exelon is just throwing it into the county’s grid and that my power is at least as likely to be coal based?

To the extent that it’s possible to talk about where “your power”, specifically, comes from, you’d have to take account of what plants, with what power output each, are near you. I’m pretty sure that it’d work out that each plant’s contribution to your personal power usage would be proportional to that plant’s total power output divided by its distance to you (here I’m assuming that the grid is homogeneous and isotropic, which it isn’t, but it should serve as a good enough approximation). In principle, you’re getting some amount of power from Hoover Dam, and Three Mile Island, and the windfarms off the ocean coast, but those would all be very small contributions, due to distance. Unless ComEd happens to own all of the power plants that are nearest to you, it’s not really relevant what the makeup of their plants is: They’ll probably try, on net, to not buy or sell much power from other companies, but that doesn’t mean there’s no buying or selling, just that it evens out. If there’s a coal plant owned by some other company near you, ComEd will end up buying some power from them and selling it to you, and likewise if one of their customers lives near a ComEd plant.

Compare an electric grid to a big water reservoir. Suppose the reservoir is fed by one big river, a few small creeks, 6 springs, and whatever rain falls on it. When you get dip a glass of water out of that reservoir, there is no way to claim that your glass contains only rain water, or spring water, or whatever.

With the grid, the power that is put in is metered, and the suppliers paid for it. And the power that is taken out is metered, and the users billed for it. You can cut deals with say a wind farm, to put X KWh in, and you buy “those” KWh at some other point in the grid, but most likely little if any of the actual power you used made the trip from the wind farm to your outlet.

It doesn’t matter though, because somebody used that wind power, and you used the dirty coal power they would have used otherwise, so in a very real sense you DID buy the actual wind power, because once it is dumped on the grid it all gets mixed up and becomes indistinguishable.

I am not getting this. Or not completely.

Let’s take Exelon and the MidWest Generation company in the broad Chicago metro area -

Exelon owns its plants. They also own ComEd which is the local delivery company and I assume they own the local transmission lines. I assume they also own the substations.

Who owns the high voltage lines and controls them however?

MidWest Generation owns the coal plants and sells its power into “the PJM Interconnection, LLC, commonly referred to as the PJM marketplace (Pennsylvania-Jersey-Maryland), a 13-state region which extends from the Atlantic coast westward to Illinois” … which then sells to local distributors, including ComEd I would presume, Exelon’s subdivision.

ComEd, as a delivery company, charges me. They are buying wholesale from Exelon nuclear and from the PJM Interconnection? and who knows from where else? but not from everywhere else. But such is what is implied by some here.

A power company tightly controls and regulates its generation to meet and balance loads but these dance must be coordinated between different companies with the involvement of different retailers at the same time? How does that work out?

Judging from this Wiki list of power plants in Illinois, I’d eyeball guesstimate that the Near West side is getting the bulk of its power in about equal parts coal/gas from the closer Midwest Generation plants and nuclear from Braidwood. The coal/gas being closer but Braidwood being more robust.

Then there’s plants further off but those are the closest and presumably the ones most likely to be making “your” electrons.

Actually, you truly are getting power from every plant connected to the grid that is generating at that moment, proportional to the distance from your house (as Chronos said). Everything else is just divying up payments to make sure all parties are trued up for what they owe and are owed.

Exelon lays claim to serving your load, so you have to pay them. They have also laid claim to generation at some cost (usually market-based), so you have to pay them that cost plus a mark-up plus/minus any adjustments for regulations that control pricing if you’re in a regulated jurisdicition.

The only time specific generation is tracked to a source is with RECs, and even that is just a paper estimate of MWHs generated at a plant, usually less some line loss assumption to account for “transporting” the energy to the load territory. No one is actually tracking electrons from individual plants to individual homes.

The claim can be made that regulated jurisdictions with their own generation source locally before buying from other markets, but that is still just divying up payments. The electrons go into the grid, which goes everywhere. It’s like rivers emptying into the ocean.

As to how load/gen are balanced, read up on RTOs (e.g. PJM)which handle that for much of the U.S. (and yes there are obvious exceptions). Mainly there are daily auctions where load/generation are bid in on day ahead or day of schedules. There’s a lot to it, but it works out pretty well (unless you’re California and decide to make stupid pricing rules).:wink: