Carrying capacity of power grids - USA and others

[Stephen Tashi]

If some technology (such as versions of fusion power) makes generating electric power vastly cheaper, will it be necessary and expensive to increase the capacity of current power grids in the USA and other countries? Or is it the case that current power grids have a lot of excess transmission capacity? - and that the limitations on power grids are mainly due to limitations on how much power can be generated?

 

[jim mcnamara]

Paging @anorlunda

This is a really good question. US FERC (Federal Energy Regulatory Commission) worries about things you describe. I think maybe anorlunda can give you a head start on finding decent answers.

 

[anorlunda]

Fair question. It depends on the geographical distribution of power plants. If we put sufficient power plants close to the power consumption sites, we depend less on the transmission grid.

Consider replacing the Indian Point power plant in New York with a similar sized fusion plant as an example.
So the most direct answer to your question is that the grid is by definition adequate for the same quantity of MW at the same geographical locations as current power plants (including wind and solar). Surely it is also tolerant to deviations from that, but the question becomes quantitative, not qualitative, so a yes/no answer can not be given.

Personally, I'm skeptical that the public will consider fusion plants safe just because the experts say that it is safe.

Edit: I should add that complete conversion of the vehicle fleet to electric vehicles would be a much bigger challenge to the grid, than change in generation technology.

 

[Rive]

For example, Germany had power generation close to main consumption (industrial areas in the south) for decades. Then cometh the wind on the north, and so they suddenly needed an insane amount of transfer capacity from north to south.
Which they found rather troublesome, un-economic and NIMBY, so loop flows got born.

Ps.: then Germany got a cage of flow-regulating devices (PST: phase shifting transformers on the east and DC interconnects on the west). So this works.

 

[russ_watters]

Fair question. It depends on the geographical distribution of power plants. If we put sufficient power plants close to the power consumption sites, we depend less on the transmission grid.

Consider replacing the Indian Point power plant in New York with a similar sized fusion plant as an example.
So the most direct answer to your question is that the grid is by definition adequate for the same quantity of MW at the same geographical locations as current power plants (including wind and solar)...

Edit: I should add that complete conversion of the vehicle fleet to electric vehicles would be a much bigger challenge to the grid, than change in generation technology.

I think you hit the key framing issue here with that last bit. The OP's question isn't really about a 1-for-1 replacement of existing plants with new ones, but rather is after what the impact of an end-user demand driven change could be. That's difficult to answer because it requires speculation about demand-driven consumer choices.

As you say, electric cars are one example; Would vastly cheaper electricity motivate much faster adoption of electric cars? I don't think it would, because electric cars are already much cheaper to run than gas cars. By far the main barrier for electric cars is the cost of the car (battery), not the cost of the energy. But maybe that's a non sequitur since their adoption will likely increase either way. More on that later.

Next, the grid isn't supplying/using a constant amount of power, so whether a large increase in energy would lead to transmission issues depends on when that new energy is used. If the energy got vastly cheaper, it might, for example, motivate switching from gas or oil heat, to electric (resistance or heat pump). Residential heat is greatest at night, whereas commercial heat is greatest early in the morning (morning warm-up). It's possible a new peak could be set at a different time than the current typical peak (afternoons in the summer), but it would take a huge shift to do so. By the same token, when are those cars being charged; at home at night or during the day, at work?

My gut tells me this isn't going to be a significant issue for the foreseeable future. We're still decades away from widespread commercial fusion power, with no guarantee it will be inexpensive (I doubt it), so it's anybody's guess what the generation landscape will look like then. The problem on the generation side is bigger/more immediate; integrating intermittent renewables.

 

[anorlunda]

Power engineers like myself make the distinction between transmission (think regional) and distribution (think neighborhood). We use the word grid to mean only the transmission. But the public and journalists use grid to mean the entire door-to-door delivery system.

New power plants are a transmmission issue, but electric vehicles (EV) strains the distribution system. The wires on every pole (or underground tunnel) on every street, plus probably the service entrance to every house and every multi-family dwelling may need substantial upgrades.

In areas where parking is plentiful, most parking spots are unoccupied most of the time. But in areas where parking is sparse, nearly every parking spot is occupied 24x7. Every one of those will need to be equipped with an EV charging station. That's a very big, very expensive proposition.