Prius Plug-in Hybrid Update

Why would they prefer coal over wind?

To pass on the savings to EV incentive?

Question is, does your PV system produce 8 kWh between 1:45pm and 3:55pm? If not, you are pulling partial from grid. You gotta have a lot of west facing panels

 

My understanding is limited ...

The utilities own the coal plants and avoid shutting them down completely due to the time and costs involved in restarting them. So there is a basal output 24/7 that is either used or wasted.

 

Even if pulling from the grid in this scenario, pre- and post-charging is pushing onto the grid and offsetting the same kWh AND leading to extremely similar net emission outcome.

In California, at least, the grid is both your fungible energy and emissions friend.

 

As a producer, you are helping your local grid to be a bit greener. As a consumer, you are part of your local grid emissions.

 

i.e, net emission of the entire system (grid), not yours. Yours is indirectly lowered by you lowering the grid average, plus any kWh from direct charging.

As Sage pointed out, pumping in unreliable renewable electricity does complicate things for coal and natural plants as it can lower efficiency by having to shutdown and restart.

There is a limit when the grid would become unstable when too much renewable contribute unreliability (see Hawaii). To manage it, you'll need battery storage or hydrogen fuel cell which would add cost. Reliability nature of fossil fuel is often overlooked by pro-renewable plugin advocates.

 

Another option to the base-load is nuclear like in France, but this is a subject for a separate discussion.

 

oops yea, I forgot to mention - while car charging, the pv is typically still over-producing, around 1.8kW - 2.1kW. Most of our panels face south west, which means we don't take as much of a hit during low Azmuth winters.
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It is because the old coal plants are steam turbines. They just don't stop right away when the fuel is cut off, and they take awhile to get going again waiting for the steam pressure to build back up.
On top of that, if they did cool all the way down to ambient, the contraction and following expansion of pipes and fittings may lead to stuff breaking. More worrisome are water hammers. Steam condenses in the pipes on shut off. If this water isn't properly drained before start up, the flowing steam can pick it up, and slam it into the pipe walls at the bends. The expansion and contraction leads to leaks; water hammers can burst pipes. The 2007 New York City steam explosion was likely caused by a water hammer.

Without the proper forms and renewable energy credits, it doesn't count to some.

I say if a person's PV system production is equal or greater than their use, and they aren't selling the SEC, then let them claim they are using green energy. The bragging rights or warm fuzzies this gives them may have been the final incentive to get them to install the PV, and without they could have just said eff it, and kept sucking from their local coal plant.

 

As a net consumer (even for those with PV systems), sure. There is not strong substitution between those generating home PV and some other agent replacing that with fossil fuel generation.

Complicate things - very little (in the PEV/BEV high census land of California). Cause problems with coal and natural gas shutdown, no. In California, the percentage of electricity generated from home solar is quite small and is all produced during peak hours and replaces natural gas generation (not coal). Natural gas generators can cycle on and off quickly and efficiently and very easily can handle the swings of home solar PV in California. It will be years before this is a significant problem here and solutions are already on their way.

 

Agree, no double dipping.

 

Thanks for the explanation.

FWIW though, I am not so sure that these coal plants at night are only being run at "minimum." The utilities own them outright, and the most profit gained is from running them full blast.

 

I think the percentage of your covered usage compared to total usage is actually 52%. See my post in the thread "I am going solar".
This means that you only have taken 48% of your usage from the grid, which is more satisfactory.

 

Cycling on and off would definitely take efficiency hit. They are not like Prius Even partial power operation can take efficiency hit.

The on-demand nature of natural gas generator is why solar can work which is also why the grid can't go 100% renewable. You can actually, but you either need a huge battery storage or hydrogen and fuel cell to store and cover the peaks and valleys of the demand.

I replied back. I intend on pulling back every kWh I produced. I will not be selling the extra, like in your case.

I guess you are right in respect to the first week. But for the entire year, it'll be 26% or lower as the days get shorter as I head into Fall and Winter.

It is going by grid region, appears to be data from e-GRID. Beyond Tailpipe Emission site also use e-GRID data. I am not sure why this says NJ has no chance of Leaf being lower emission than a Prius.

BTE site said (for my zip) Leaf would emit 190 g/mi which is lower than Prius 222 g/mi. CMU estimate uses delayed charging and consumption-based emission so it may be more accurate.

Edit: I don't know. There is no way Leaf would be cleaner in Colorado than in New Jersey, as this would indicate.

 

The blue one has the Plugin Hybrid Synergy Drive badge. If it has double the EV range and lighter than Gen3 regular Prius, WOW.

 

Natural gas generation has been used this way long before PV registered on the grid. Unable to find a documented source, but have discussed this with a family member who is an electrical engineer who worked for a midwest electrical utility with gas turbines. He noted these peaking units take very little startup penalty compared to their overall efficiency.

Also, since home solar is a tiny percentage of overall energy supply to the grid and most gas turbines are already running below capacity , it's not some manic-run-for-only-a-few-minutes rapid cycling on/off, but mostly cranking up the output of already running units. Even the peaking units have always run for several hours at a time. The duration of peaking runs should not become an issue as solar PV prevalence continues to grow.

Natural gas-fired combustion turbines are generally used to meet peak electricity load - Today in Energy - U.S. Energy Information Administration (EIA)

There are higher short-medium term costs to going 100% renewable, but it can be done. The long term costs of not going 100% renewable is more undesirable.

 

Well, running at the minimum means the turbines are outside their efficient production range. So burning a 'little' more coal increases the kW made per ton burned. Even if the utility owns the wind power, it might make financial sense to idle a few wind turbines and run the coal above the minimum.

I think the real issue arises in areas that still have a decent amount of coal and also a lot of wind.If the nightly wind output was enough to meet demand, the coal plants would still only go to idle and not shut off. Without a storage solution for the excess wind, or enough natural gas CCGT, the utility doesn't want to risk having a coal plant go down, and then have service interruptions during low wind periods.

 

That is the excuse anyway.

 

...these maps suffer from what I call CO2 gerrymandering...how you show it depends on how you average the high coal areas with the low coal areas.

 

Those maps are generally of the areas that share energy.
For example, MISO takes bids from energy providers in a specific region. They have a particular region they accept bids from. I suspect this is due to transmission line capacity and losses over distance.

Minnesota has aggressively been shutting down cold coal plants, so MISO has, on average, gotten a lot cleaner. Although it was one of the dirtiest, it still has a long ways to go.
This is why your specific utility's grid may not have that big of an influence on your power make-up. It is more dependent upon your region's power generation.

 

...it used to be we here thought the EPA power Profile site gave a pretty good idea for each zipcode. But as far as I know that site has not been updated so it goes back to pre-2012 before the coal really started to decline.

Actually looks like PowerProfiler was recently updated to 2010 data but still too old. South Jersey shows 35% coal and 20% gas of course lots of nukes there. I got to tour inside one rxr (before the fuel rods thank you). I do not know why they don't give us 2012 data then it would be decent, and it would also match the regulatory basis for the Clean Power Plan final regs to be announced soon.

How clean is the electricity I use? - Power Profiler | Clean Energy | US EPA