Recently, a bunch of different power companies have sent letters to me asking me to start buying power from them instead of my current one, and my current one has sent letters to me asking to me to keep buying power from them. This has led me to ponder how the hell electricity really works, when you get right down to it.
No matter what power company I use, I get my power from the nuclear power plant Barsebäck. Does this mean that there are several power companies competing to buy power from Barsebäck and then resell it to me? If so, why doesn’t Barsebäck simply eliminate the middleman and sell power directly to me? And how do these companies do it, anyway? It’s not like they can drive trucks up to Barsebäck, load them full of electricity and then drive around delivering it.
Unfortunately for the simplicity of this question, the preceding paragraph isn’t, as it turns out, entirely true. One power company uses as a selling point that if I use them, they won’t use Barsebäck nor any other nuclear power plant, nor oil or coal, but provide environmentally hip power like sun or wind. How do they do that? When I switch power companies, no-one has to come to my apartment and change anything, and the switch is completely seamless. How come the dancing electrons suddenly come from a sun power plant instead of from Barsebäck? How can anyone even tell?
I know this question is a bit fragmented. That’s because I have trouble finding the words to describe what I mean. Still, any help is appreciated.
Forget about the electrons. The power grid is more like a bank account. Power stations make deposits and consumers make withdrawals. As long as the deposits and withdrawals balance, everything is OK. When you make a withdrawal, asking what the original source of the money was is an unanswerable question.
I’m not sure how they do the accounting and billing.
There’s three stages: there’s the generating companies that run the power stations. There’s the company (normally a monopoly) which operates the high-voltage transmission grid, which purchases the power from the generators. The distributors then purchase power from the transmission system and sell it to you.
The environmental ones will have an arrangement with the grid operator that ensures their purchases are accounted for as electricity from alternative sources. It doesn’t mean that the power reaching your home has come straight from a windfarm, but it theoretically ensures that your purchases don’t add to non-renewable electricity being generated. That’s assuming that the setup doesn’t simply allow the grid operator to ‘allocate’ all of its purchases from renewable sources as the ones for the environmental companies, and increase the non-renewable production to provide for the regular companies.
(BTW, I’d be very surprised if your power is solely sourced from one station. That would mean any operating problems or regular stoppages would leave you without power. You’re almost certainly on a far wider grid system which takes power from many sources.)
IIRC electrons have an average velocity that is only like walking speed in a wire carrying a fair share of current (though this number obviously can vary at least as widely as can the current density - somebody please chime in with better info if you have it). Average velocity means how far the electron gets over an extended time. In alternating current they reverse, for example at 50 Hz or 60 Hz depending on where you live. So the electrons you are using - well, taking advantage of - are pretty much the same ones day to day.
The power grid is sort of like a bank account, with depositors and withdrawlers, but there is a difference. A significant fraction of the energy that goes in (I think it is like 10% to 30%) gets converted to heat and electromagnetic radiation that just weeps out of the whole system, lost for our practical purposes. So a joule (about enough energy to lift a quarter pound by one yard) that gets put in a thousand miles away doesn’t let you pull a whole joule out at your house. In this sense you are using more energy from the plants that are closer, but this distribution process is in an ever-shifting equilibrium dictated by physical laws and the details of the whole grid moment to moment. Bank accounts don’t care how many miles apart the deposits and withdrawals are.
In Tennessee the TVA has 3 windmills currently producing 880 KW ea. and are adding 15 more producing 1.8 MW. There are also 15 solar sites and one methane burning power plant. All of this is fed into the grid.
As a residential consumer you can sign up to buy blocks of “Green Power” at a premium price.
It would appear on the face of it that Green Power costs more to produce than conventional and hence has to be subsidized in some way. The Green Power con is a promotional gimmick for the tree huggers and a way to mollify the general consumer.
Because of hydro-power generation in the valley Tennessee has one of the lowest rates in the US by a factor of 7!
Probably true, today. But then for most of the last century we’ve spent a lot of research & development money on increasing the efficiency of fossil-fuel & nucleur generation. If there’s enough consumer demand for ‘green power’, then research may result in consideral efficiency improvements in this, too.
Somewhat similar to the market for organic produce, which, driven by consumer demand, is now a sizable department in nearly every grocery store.
P.S. You don’t count hydro-power, like the very cheap TVA electricity you cite, as 'green power"? It’s certainly renewable, and largely non-polluting.
Hydro power in the valley is the principal reason for low rates. Initiated in the 1930’s as a means of flood control and power generation for rural use. It was not intended as an example of green power.
BTW Check out the new wind generators. They are made in the Netherlands by IIRC Vestas.com. They are currently revising their URL site. Components are transported up the mountain road on a 32 axle dual wheeled trailer with load balancing features and a driver at the rear end.
You have a 50 gallon drum that hold potion x. Potiion x is manufactured by various companies, but no matter how they produce it, it becomes potion x.
All the buyers of potion x withdraw from the 50 gallon drum. None care that the suppliers cause polution or waste to produce potion x.
Suddenly, a new player is allowed to produce potion x and put in the drum (at the expense of some other potion x producer). This new player makes potion x and causes little polution or waste. But to add any potion x to the drum (at the expense of some other potion x producer) he needs someone to pledge to buy it.
So, Joe Public agrees to buy 1 gallon a month from him. And the newer cleaner potion x producer adds his gallon to the drum. So now 49 gallons were produced by the old crummy potion x producers, and 1 gallon was produced by the newer/cleaner/greener potion x producer.
When you buy your gallon, you are not getting the exact gallon your potion x producer added, rather, you are guranteeing him a stake of 1 gallon as long as you keep your pledge to buy from him…you gaurantee that X amount of the 50 gallons comes from the new/cleaner/greener potion x producer…cutting out some production of the older crummier dirtier guy.
I can answer. I spent six months doing finances for a company that owns wind turbine plants so I got a pretty good view of how the system is set up.
At the lowest level, you have the powerplants. Each powerplant has an owner/operator company who is responsible for the day to day operations of the plant and making sure power gets to the grid. Usually these are either small companies you never heard of or paper subsidieries of larger companies.
Next, you have asset management companies that actually own the owner/operator companies (like Enron). They enter into a power purchase agreement with the power company. The power company (like ConEd or PSE&G) agrees to buy so many megawats at such and such price for x years (typically 20). It is the asset management companies responsibility to provide that power.
And then you have the power companies. Basically as far as I know, they own the various parts of the power grid and are responsible for distributing it to your house. They buy and sell power from various sources and charge you to send it to your home.
I should also point out that all these companies can be subsidieries of the same parent company and that plants can actually have multiple owners. It can get pretty complex.
Oh and in case it wasn’t clear, the transactions that take place here are “paper” or “electronic” transactions. It’s not like anyone keeps track of which electrons came from whom and where they should go.
But dams are extremely invasive in the environment. Certainly they don’t pollute, but they inundate huge tracts of land that otherwise would have been undisturbed. I have mixed feelings about that myself. The environmentalists have a valid point, but nonpolluting power that’s free as long as there’s water in the river seems too good to pass up. I actually feel a twinge of envy when I read about a country or city that gets its power entirely from dams. No HC pollution, or worries about supply.
Priceguy, where does Sweden get its power generally, besides from nuclear plants? Isn’t it mostly hydro?
Tracking of electronic transactions of electricity between different utilities, grids, networks, plants, etc. is an entire business in itself. I’ve worked on it and it was so God-awful boring and complicated at the same time it made my brain bleed. My sister now works on it and is God-awful bored over it too…
TVA also has its low generation cost from its nuclear capacity and its very cheap coal, not just from the rather limited hydro resources they have (and I don’t count Raccoon Mountain, since IIRC that’s a net loss of electricity). TVA’s coal and gas plants make up about 2/3 of the entire net generation of the total capacity of 31-32 GW. And Browns Ferry and Sequoyah are pretty big (2.2 and 2.3 GW respectively), so I’m thinking that hydro actual generation must be a bit less than 25% of what TVA uses for electricity production…
As a stand alone facility, Raccoon Mountain is a net loss.
It acts as a load leveler to store energy during hours of low consumption from the grid so it can supply that energy back to the girid during hours of high demand. As such it is an overall net gain.
How exactly? It’s pumped storage. The pumps take more energy to pump the water up than is produced by the water coming back down. Unless you’re saying that the natural water sources and rain supply enough extra water to account for this inefficiency. But in that case it would be a net gain from a stand alone viewpoint, so your statement is unclear.
To understand why I say that pumped storage is a net loss, look at this chart from the EIA for pumped storage net energy “generation” (which is really “consumption”) State-by-State.
I call “consume more power…than they generate” a net loss. The purpose of pumped storage is to be a battery for electricity that’s already been generated. One can argue that pumped storage allows for energy to be generated at a time when other plants may be operating “less efficiently”, but there is no way that the power required to pump the water is worth any such efficiency loss. In fact, pumped storage at many other sites (like Dinorwig, where Fierra, hibernicus, and Tansu, and I recently toured) are designed for use during peak loads.
:smack:
Its about overall operating costs, installed capacity, and the generation capacity on-line to satisfy demand. Steam takes time to start up and shut down hence hydro with comparitively rapid start up and shut down is used as a load leveller.
I had actually heard that in several cases that pumped storage systems could be run at about breakeven for cost because they could purchase power from the grid during offpeak times for dirt cheap to pump then, sell power they generate at much higher prices during peak load times.
I don’t remember where I heard it, so it could be someones spin to promote a project or something.
If the argument was about cost all along, then I would not have disagreed. Pumped storage can and often does make sense from an economic standpoint. Otherwise they would likely never be built.
But that’s kind of irrelevant, since what I said exactly was:
If that point is in dispute and is going to be discussed then I will discuss further. Otherwise, I don’t see the disagreement or the need for the smackie smiley in this thread.