How does the smart grid play a part or support a wide-scale system for charging electric vehicles?

[Billbrasky52]

I wanted to start a discussion on how the smart grid has an influence or supports the possibility of having a wide-scale system for charging electric vehicles.

 

[davidbeach]

If all they are is a load, I'm not sure how much "smarts" are necessary. If they become a tappable source of energy, then there needs to be some smarts to control that process.

 

[Billbrasky52]

So if they were to be a charging station as well as something such as a solar panel setup, what kind of smarts could be used?

 

[moltenmetal]

The notion that electric vehicles can be used to dump power back to the grid when idle assumes that electric vehicles are fitted with AC inverters capable of generating 240VAC.

They don't. None of the commercial electric vehicles have this capability. And adding it is expensive, unless you want that inverter to be very small- limited to 1 kW say, and hence the storage impact per car to be very small.

The level 2 charging stations you see at shopping malls aren't really charging stations at all- they're merely "smart" (expensive) AC outlets that look for a vehicle's handshaking signals before they turn on the 240VAC. They have no access to the battery except through the car's onboard charger, which is a one way (AC in, DC out) device. There are DC high rate chargers but those are a niche right now.

Then there's the battery replacement. EV battery replacement currently runs between $1 and $3/100 km driven based on a 3000 charge-discharge cycle life, which is not a trivial cost of ownership. Any additional charge/discharge cycles put on the cells by using the vehicle as portable grid storage is going to drive up that cost by causing the cells to fail sooner. Just because you have the battery in the car doesn't make grid storage economics any more attractive. You don't really need virtually any of the benefits of Li-ion batteries for grid storage, so you don't need any of their disadvantages either- including their high replacement cost.

One thing that a "smart grid" could make use of is the ability to schedule charging of electric vehicles to reduce peak demand. Regrettably, that would leave people potentially unable to drive home from work, or the mall etc. Not really practical.

All that said, the majority of EV charging is done off peak, and that will continue as long as time of use rates remain favourable.

 

[racookpe1978]

Any truly "smart grid" would immediately disconnect every EV charger as soon as the first load needed to be removed.

But then the enviro's would immediately complain about not getting their "free" ride home from their local during-the-day charging station that everybody else is paying for and subsidizing, and the Washington controllers of our lives would place EV car chargers running at the peak hours of use (afternoon and early evening) as the last-to-be-cut-off user. 8<)

 

[ccfowler]

Plug-in electric vehicles introduce very substantial parasitic losses that almost everyone conveniently omits from discussions of their sublime wondrousness. These include step up losses at the power generation site, transmission losses, step down losses, distribution losses, step down losses to the consumer voltage level, battery charger losses, battery losses (what goes into the battery is always significantly less than what comes out, but that is rarely understood by most EV fans). Actually powering the EV involves the additional losses of the motor(s), motor controls, and any mechanical drive elements.

When one does some realistic calculations on these very real losses, the overall efficiency is found to be very modest under the most favorable honest analysis. Similarly, EV's are commonly described or designated as Zero Emission Vehicles, but when appropriate losses and actual generation emissions are suitably included in a complete analysis, emissions are actually quite substantial.

To consider using the battery system of an EV as a potential source of grid support, all the attendant losses imply very limited potential benefits against substantial energy and economic burdens.

EV's actually represent a means for shifting the location of emissions geographically, such as reducing emissions in a highly populated area while actually incurring the emissions at a more remote and less populated area. Such a potential benefit may be real and valuable, but it is not without adverse burdens being imposed somewhere.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[davidbeach]

what goes into the battery is always significantly less than what comes out, but that is rarely understood by most EV fans

You might want to rephrase that. ;-)

 

[IRstuff]

The only thing I can think of that might be applicable is if there was some need to subsidize the cost of charging, such that an EV could be charged at Tier 1 rates without having a separate utility connection, i.e., when the EV is charging, the smart grid knows that fact and excludes that charging from the regular electricity usage in a home. I'm normally at Tier 3 for any additional consumption, and running an extra mains connection is probably going to cost money, as is the meter attached thereto. Having the single meter separate the EV charging from the rest would be a reasonable cost savings.

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[ccfowler]

davidbeach, you are absolutely correct! What energy goes into a battery is always substantially more than the energy that comes out!

Whenever subsidies are required on a continuing basis for something, it inherently cannot be truly viable. Currently, EV's are the beneficiaries of significant economic, political, and philosophical subsidies. Assuredly, there are applications or circumstances where they are highly appropriate, but as with anything, they are not the one and only best choice for all circumstances or applications. Unfortunately, political, philosophical, and marketing pressures are serving to mislead people to have unrealistic beliefs and expectations regarding EV's.

True off-peak charging of EV's can serve to help optimize overall efficiency of energy and physical plant usage, but on-peak charging of EV's should be avoided as a normally needless burden.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[cranky108]

Tier 1 rates, and Tier 3 rates sort of sounds like some kind of subsidies and taxes. Does this have something to do with the duck curve, and should that not have an effect on EV charging costs?

A smart grid (what ever that is) could allow charging of EV's during the midnight hours, and not the 5PM to 9PM hours. But a simple timer could also do that.
Remember the old odd, even gas days, maybe we need an odd, even hour charging times.

 

[moltenmetal]

ccfowler: here are the numbers I've been using in my own calcs. I'm interested if you have better numbers, and if so, what the bases of those numbers are.

grid losses, power plant to user: ~ 6%. My own local utility only charges us only 3.4% for grid losses, but the 6% average number in North America is widely referenced.

charger efficiency: 93%. That's the nameplate efficiency of the charger I used in my own EV, verified by measurement of mains draw and DC output voltage and current. It's power factor corrected, so my mains measurements are pretty accurate.

battery efficiency: DC Wh in (from charger) / DC Wh out : 94% for LiFePO4 cells. That's a mean based on hundreds of measurements made by another EV user who is an electric engineer. The battery efficiency drops below 90% as ambient temperatures drop below 0 C though, requiring battery heating during charging which is of course another loss. Li-ion cells are surprisingly efficient- the only losses are ohmic and a little mass transfer, since there are virtually no parasitic chemical reactions going on with this cell chemistry.

Multiply 94% x 93% * 94% and you get a pretty impressive efficiency of 82% from the power plant to energy stored on board. That compares quite favourably with the 81-83% well to tank efficiency for gasoline, based on the GM/Argonne National Laboratory well to wheels study, and cross-checked against a similar EU study. The largest single loss in the gasoline energy chain is refining.

Taking into account that the controller and motor of an EV are very efficient- upwards of 85-90% combined- you get a very efficient means of transportation. Fuel that with a green grid like the one we have in Ontario, Canada (averaging around 40 g CO2/kWh) and you get a means of transportation that gives most public transit a serious run for its money in environmental terms.

As a grid electricity storage medium though, it's pretty lossy.

 

[IRstuff]

But, what does it take to generate the power in the power plant to supply the electricity for the battery? Isn't that part of the equation as well?

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[moltenmetal]

IRStuff: absolutely. But our local grid is only 9% fossil, the balance being nuclear and renewables (principally hydro).

Even so, unless your fossil fuel power plants are themselves real dinosaurs, the efficiency of an EV from power source to wheels is competitive with that of an IC engine car fueled with gasoline or diesel. If your grid is supplied entirely by old coal-fired power plants, then you could end up with an overall source to wheels efficiency lower than that of an IC engine car- but most grids aren't that way any more.

 

[IRstuff]

Well, you're lucky. According to USG, 66% of US power is generated by fossil fuel. That's likely to have an increasing mix of natural gas while their prices are low.

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[cranky108]

I think something is missing here. The efficiency of an IC engine is not in the 80% area. You were just talking about well to tank efficiency.

On the other hand, an IC engine can use other fuels, if modified, and could become more efficient, again with modifications.

One problem here is that the more complicated something is, the more it costs to maintain. Another issue is some of us don't drive cars because we can't transport wood fuel for our home with a car.

It's all well and good to be efficient on one hand, but not if it costs you on the other hand.

 

[moltenmetal]

Cranky: the power plant heat engine is typically more fuel efficient than an IC engine vehicle is. If the power plant/energy source to on-board energy efficiency is similar between gasoline/diesel and electric vehicles- and it's nearly identical- then the electric car wins in energy efficiency terms. That's what my calcs show. With a good grid like ours, it wins by a country mile in environmental terms. It would likely still win with a 60% fossil grid, though not by the margin that it does here.

Obviously the electric car isn't a 100% replacement for all IC engine land vehicles- but it IS a viable replacement for an enormous amount of the person-miles covered by people in vehicles. As to costs, the IC engine car wins hands down in many locales due to the absence of carbon pricing. My electric conversion breaks even, barely, compared to my Prius C hybrid. No carbon tax here yet.

 

[cranky108]

Agreed that power plant do beat the IC engine in efficieny, but when you included power plant numbers and not IC numbers it looked a little misleading. So I pointed it out. Not that I disagreed.

I think there is an even bigger carbon waster that has not even begun to be discussed. That being the melting of old cars and making them into new cars. If a car life can be doubled, then that energy can be cut in half. But at a cost of so many car salesmen jobs. It's the perception of newer is better, and only looking at the transportation cost, and not the cost of the energy to build the thing in the first place.
It's the whole disposable concept that's the problem.

And what ever happened to aluminum and glass recycling? At one time the recyclers paid people to recycle, not that you have to pay to recycle like today.

Smart grid is not a fix, it's a managment tool.

 

[IRstuff]

"At one time the recyclers paid people to recycle, not that you have to pay to recycle like today."

"They" still do, sort of; they actually reimburse you for the CRV fee you paid to buy the product originally. I got $43 last time I turned in a bunch of plastic bottles and cans. This, of course, is only valid in a handful of states that demand CRV at the point of sale.

Aluminum and glass recycling still goes on, but what I've read is that there is a surplus of recycling material, and prices have not been kind to recyclers. I think there's also another issue in that the energy and resource consumption to recycle materials is not that small, compared to processing raw materials.

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[moltenmetal]

Recycling of easy to recycle metals like copper and aluminum is still a huge business- people are still stealing these materials and collecting them at the roadside here for a living. It's the plastics that are the problem- they're too low value and far too heterogeneous in post-consumer wastes like cars etc. These devices tend to consist of many different incompatible polymers and fillers etc. that are hard to separate from one another in a meaningful way to make true recycling profitable.

The embodied energy of a car isn't trivial but it's nowhere near the amount of energy used to operate it during its lifetime.

Electric cars are really simple, with fewer components to fail than in a comparably equipped IC engine car- numerous entire systems are just absent from the EV. Battery replacement is expensive, but not actually all that difficult. Not so for hybrids or especially plug-in hybrids, which have basically two cars' worth of gear in them to potentially go wrong. That said, my own Priuses have proven to be very reliable and people do drive Priuses 500,000 km as taxis routinely before they scrap them. Of course, with a plug in hybrid like the Chevy Volt, even when the batteries go the way of all things, you are still left with an IC engine hybrid with typically very few miles on its engine.

 

[cranky108]

Yes I know about copper theft, but I don't see the homeless collecting aluminum cans like they did at one time. And no we do not have a CRV here. Finding a recycling place is difficult. The trash services offer recycling, but they charge extra for that, and for all I know it might also be tossed with the rest of the trash.

Actually the newer cars are much more complicated to repair than the older ones. It's all the electronics, computerized displays, etc. (I believe in keeping things as simple as possible, within reason).

I actually looked at putting a timer on my hot water heater years ago, but what I found was that when the water was allowed to cool off, it dropped sediment, which filled the tank over time. And that is the sort of things that will start happening when we get more into smart grid. Unintended side outcomes will happen.

Do you think smart grid control will work well for the night watchperson who needs to charge there EV during the day?