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The Future of EV Home Charging and the Grid

Discussion in 'Energy, Environment, and Policy' started by gnuarm, Jan 17, 2019.

  1. StealthP3D

    StealthP3D Active Member

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    That's false (and don't call me "dude"). Regulators have lawyers and they work with lawyers who collect data and facts to make their case. The can also hire outside lawyers and consultants when and if necessary. Courts are a last resort but even when you go to court you need facts and data to support your case. It would be extremely incompetent for a regulator to only rely on utility supplied data, especially if that data wasn't passing the smell test.

    If they are doing their job they most certainly are in charge. That's what regulators do, ensure the utility is following the rules. They are like a traffic cop. The traffic cop is in charge of making sure everyone is following the rules.

    I understand fine. I am talking about local distribution, not generation. The local distribution lines cost a lot to install and upkeep. Utilizing them at a higher rate allows them to cost those expenses over more kWh's of electricity sold. In otherwords, higher utilization of the local distribution network makes the local distribution cost less per kWh.

    I'm not sure why you don't understand that - it's not a very difficult concept.
     
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  2. philiparnason

    philiparnason Member

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    Man, this thread is full of snide remarks! That is really unfortunate. This is an interesting subject to all of us---let's give each other the benefit of the doubt and try to increase the total amount of knowledge on the subject. I would only like to add this video I came across a few months ago. It is over 40 minutes but well worth it for anybody interested in the effect of EVs on the grid:



    The research project was conducted in conjunction with the Victorian Department of Transport’s Electric Vehicle Trial, and this video is the summary of this research. If you prefer to read the executive summary it is here:

    https://www.parliament.vic.gov.au/file_uploads/EIC_58-13_Text_WEB_1MNYcV8K.pdf
     
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  3. Feathermerchan

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    The following centers on distribution costs and operation.

    Can't find a good article at the moment but it used to be that Generation was a utility's single largest cost on a per kWh basis. I think it represented about 2/3 of the total energy cost. Then Transmission and Distribution were near the same per kWh and so about 1/6 of the cost per kWh. Anyway utilities can easily know which meters are connected to which transformers and if they have smart meters they can know the transformer load for any time of the day. They just sum the metered loads by transformer.

    Transformer sizing is usually done by using an economic model designed to minimize total owning cost and so also minimize kWh cost to the end user. As such we used to design the system to load transformers to 130% of nameplate for the summer and 160% for the winter. When loads are increased, the system can be made to notify when a transformer is being loaded beyond what is desired so it can be replaced with a larger unit. Similarly, the distribution system can be monitored for overloads at the branch level. At the feeder level, many have 'real time' monitoring of load.

    The design process above starts with load 'sheets' that contain information about the dwelling size, kind of heat, and assumptions of cooling requirements and efficiencies. The sheets are different for residential and commercial construction. For both cases, allowances are made for known additional loads such as EV charging, hot tubs, pools, etc.

    So a utility certainly can know where overloads are occurring and take action to remediate as necessary. They can also design for EV loads when doing new construction. Their costs may go up but we will be buying mode kWh so they should be able to recover costs in the normal way.

    Say a customer adds a hot tub with an 11 kW heater (happens all the time). Depending on the system, it may present an overload which would require a transformer upgrade.
     
  4. nwdiver

    nwdiver Well-Known Member

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    #84 nwdiver, Jan 21, 2019
    Last edited: Jan 21, 2019
    ??? You... you realize that burning coal, oil, gasoline, diesel, propane, etc is basically the same chemical process... right? You're converting Hydro-Carbons and Oxygen into Water and CO2. They ALL make water... in roughly the same proportion...

    Coal isn't carbon intensive because it's coal, it's carbon intensive because it's used in thermal generation which has a lower efficiency. You need more kWh of primary energy to get the same kWh of useful energy compared to other forms of generation.

    Not really; ~35% is about the max for thermal plants like coal. ~60% for combined cycle natural gas.
     
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  5. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    Dude, there is no case. The regulators won't go out and tell the utilities to do anything with EV charging. That's not what they do. The utilities will make a case showing that customers are putting more and more EVs on the local distribution grid and that grid needs to be expanded at a cost that will be passed onto the consumer.


    Yes, very good analogy. Traffic cops don't tell anyone to invent a new type of turn signal or that we need to have staggered work times to reduce rush hour traffic.


    What you don't get is that adding overloads which require expansion of the local grid is not "higher utilization". It is over utilization. It is the generation that can be tapped at night and off peak times and will produce better returns in capital with higher utilization.

    Sure, there will be higher utilization of the local grid too, but as I've provided data to support, it is very likely that it will be over utilized if significant measures are not taken to minimize the impact of EV charging. I've laid it all out clearly complete with numbers. If you really can't understand that even moderate adoption of EV home charging without charging control and coordination will result in the need for widespread capacity increases, I really can't help you further.
     
  6. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    So when the transformer is increased in size, what happens to the transformers supplying that transformer? What about the wires both upstream and downstream? What would happen if virtually all the transformers feeding the home had to be increased because the peak loads doubled? Would that not also require upgrades to the rest of the distribution system feeding these transformers?

    So we have some better vocabulary, do these last transformers have a name we can use?

    While the peak kW load is what determines the size of the transformer, that may or may not be associated with an overall increase in kWh that would provide revenue to pay for the equipment. I think it is a different animal to upgrade the occasional transformer because one or two homes added hot tubs and seeing 20-50% of the homes add 15 kW charging. They won't all be on at the same time, but it isn't a stretch to see there will be times when many will be on at the same time, for example the night before a holiday weekend I would expect a LOT of them to be charging at once.
     
  7. nwdiver

    nwdiver Well-Known Member

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    That absolutely IS what regulators are supposed to do in accordance with their mission. That's part of the rule making process. If XYZ utility says they want to upgrade a transmission line for $200M but the PRC staff discovers that a simple demand response program can accomplish the same goals for $50M. Guess whose not getting approval for a $200M upgrade. Rate cases are a GRUELING process open to the public that often involve dozens of stake holders. If the PRC staff is too ignorant to spot something John-Q public has the right to speak up and be heard too.

    Charging control and coordination is already inherent in all Tesla vehicles. If I start charging my Tesla at 80A and my neighbor also plugs in his Tesla and my other neighbors hot water heater turns on guess what happens? I'm no longer charging at 80A. Tesla vehicles are already 'smart' enough to see a voltage dip and reduce the charge rate.
     
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  8. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    Coal has little hydrogen left in it. That's the point. It is burned mostly to CO2 and less water because it is mostly carbon... and some rock, that's where clinkers come from. Oil, gasoline, diesel are all petroleum which is hydrocarbon and propane is just a lighter form of hydrocarbon. The very small hydrocarbon molecules have a higher ratio of hydrogen to carbon. While gasoline is pretty much 2 H to 1 C, methane is 4 H to 1 C. Propane is 8 H to 3 C or about 3 to 1.

    Here's a quote of coal's composition.

    The Chemistry of Coal

    In both cases, bituminous and anthracite, there will be more than twice as much CO2 as H2O produced. In anthracite coal the ratio will be five to one.


    Coal is carbon intensive because it is mostly carbon... period. The efficiencies of the generation process are a smaller factor than the fuel itself.
     
  9. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    Where would the "demand response program" come from? If it exists, how do the regulators find out about it? Someone, somewhere has to actually take some action to make sure these things do exist and are publicized so they become a part of the rate system. That is exactly my point. They won't happen by themselves. The regulators are not in a position to create these things. The best we can expect from them is to encourage the utilities to spend money on doing studies to evaluate what is available. I've never heard of a regulator requiring a utility to develop anything like this.


    That still doesn't do anything to prevent the utility from also seeing the overload and responding by upgrading the distribution equipment. I've seen others post that exactly this will happen. At some point the rate of upgrades will result in higher bills to everyone including those who don't drive EVs.
     
  10. nwdiver

    nwdiver Well-Known Member

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    #90 nwdiver, Jan 21, 2019
    Last edited: Jan 21, 2019
    Looks like I was off the mark a bit in appreciating the energy derived from combining C + O in burning coal. I think a way of conceptualizing this is that the closer a fuel is to Hydrogen the cleaner it will burn. That said there is still a significant amount of hydrogen in coal.

    I was surprised at the low energy content of coal....

    Coal; 41% H2 (30MJ/kg)
    C137H97O9

    Natural Gas; 80% H2 (55.5MJ/kg)
    CH4;

    Gasoline; 70% H2 (46.4MJ/kg)
    C8H18;

    Hydrogen; (~130MJ/kg)
     
  11. nwdiver

    nwdiver Well-Known Member

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    The demand response program can come from several places. The legislature, the PRC staff or a 3rd party that becomes an intervenor in a utility rate case. The regulators can find out about it in several way. The legislature, the PRC staff or a 3rd party that becomes an intervenor in a rate case.

    FERC order 745 codifies demand response into the market basically requiring ISOs treat demand response in a similar way to peaking power. You don't always need to create a 'program', all that is necessary is the right market signal and the programs will be created due to that signal.

    ... sure it does; Lower demand on a secondary transformer because of lower voltage limits stress on the feeder line. The utility typically doesn't have visibility on the 240v level only the ~7.6kV level. A Tesla is going to curtail power long before other appliances that can't even 'see' voltage. This alone will mitigate increased demand during peak times combine that with behavioral changes due to TOU and it's a moot point.
     
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  12. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    The ratio of hydrogen to carbon varies from 4 to 1 in methane to less than 1 to 1 or even 1 to 2 in coal. That's a big difference.

    The difference in "energy content" between coal and other fuels is because you are citing numbers based on weight. A carbon atom is 12 times heavier than hydrogen, so sure, more hydrogen means a lighter fuel.
     
  13. Feathermerchan

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    The transformer next to you house owned by the utility is called a distribution transformer.
    The transformer in a substation is called a substation transformer.
    A Tesla charging at 40A (about the max you can expect) is 9.6 kW not 15 kW.
    Charging a Model 3 LR using the supplies cord (32 A) is 7.68 kW
    In the North Texas area out peak load is usually June - September, Monday - Friday, Noon to 8 PM.
    Weekends and holidays are excluded because industry and business are generally shut down or at greatly reduced usage.

    When my house was built, most people (and builders) installed A/C units with 8.0 SEER or so. Average size was 3-4 tons.
    Now I think the standard is 12.0 SEER and my next unit will be far above that. So a 3.5 ton 8.0 SEER unit draws about 5.25 kW while a 3.5 tom 12 SEER unit draws about 3.5 kW. That is a difference of 1.75 kW. We also know that LED lighting, LED TV's, refrigerators, washers and dryers have reduced demand. So there is some wiggle room.

    I have natural gas so my winter demand is almost nothing. But those with all electric service often end up with a winter peak demand higher than their summer peak (even with a heat pump you'll be running some resistance heat at the peak) so that can determine their transformer and service sizing giving more overhead for adding extra load in the summer.

    While we're discussing extra capacity, our sizing algorithm always over sizes by a certain amount because we do not want to have to come back to the house or subdivision and add capacity and we know that people seem to add load in various ways.

    Fun fact - Our research shows that on the average a water heater (5 kW) adds only about 500 W to the peak demand at the generating level. Probably close to that at the substation transformer level. Water heaters just don't run much between noon and 8 PM.

    Generation in Texas has been 'deregulated' for many years so as load grows generation will also grow.
    We in Texas now get 20% of our generation from wind. And it will only grow. So our Teslas get greener every day.
     
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  14. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    Which of these are current working on the problem??? You can postulate that "stuff happens" all you want. That won't make it happen. My point is that as consumes, we have an interest in making it happen. So we need to make sure our legislatures know we want this to work in our favor. But that won't make inventions happen. That will require all the parties to work toward a solution that benefits us all.


    Sorry, I don't know what you are referring to here as "programs".


    Still not following you. If the line is not overloaded the voltage won't sag and the charger won't cut back. If it does sag because of an overload, why won't the utility see that? If the charger can see it why wouldn't the utility see it?

    I didn't say anything about TOU or what you are calling "peak" times. In fact everything I have been talking about is night time charging when total demand on the grid is low so it is the best time to charge cars. Unfortunately this coincides with the highest (by a factor of over two) usage from heat pumps (the straight electric backup really) on cold winter nights. Interestingly enough this also coincides with the highest expected charging demand because of cold weather related effects on batteries.

    So the availability of generation capacity for charging combined with the cold weather demands for residential heating will create high residential usage in winter nights. Yes, I can see a problem with the utilities wanting to expand distribution rather than developing and trying to get consumers to use a program of utility controlled charging and making sure that program (the bureaucratic type) is fair to consumers, both EV owners and the rest.
     
  15. SageBrush

    SageBrush 2018: Drain the Sewer

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    #95 SageBrush, Jan 21, 2019
    Last edited: Jan 21, 2019
    The lion's share of energy release is from the oxidation of hydrogen and not the oxidation of carbon.

    A good example is methane ( ~ CH3) Vs hydrocarbons (CH2). Just looking at the chemical formulas imply that methane releases 50% more energy on combustion per equivalent mass.
     
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  16. nwdiver

    nwdiver Well-Known Member

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    Here's one example;

    By program I mean an organized way to provide an incentive for shifting load to where it's more favorable to the grid.

    The secondary transformers are a 'bottleneck'. A Tesla is unique compared to other applicate such as a tankless hot water heater because once voltage sags the Tesla will slow its charge rate. Other appliances will keep pulling down voltage.

    Not really sure what your point is here. If you're suggesting that we need expensive upgrades to keep building out the EV fleet that's not true ~99% of the time. There may be an odd case where 4 households want 2 EVs each and their local transformer physically cannot deliver the energy but that's going to be REALLY uncommon.
     
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  17. Feathermerchan

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    Regarding regulators. They are generally not business people and may or may not have any operating experience at all. If utilities always did what the regulators wanted/asked, I think we would be in a much worse place. In Texas at least, regulation is supposed to serve as a substitute for competition because the investor owned utility has been granted a monopoly. I can cite several examples of where the regulators had an idea that we contested because we thought it would not work and/or would cost our customers more money than necessary. Sometimes we prevailed and sometimes we did not.

    Example 1: When we wanted to start installing 'smart' meters we had the option of buying meters with and without a remotely operated disconnect switch. This is useful when you need to disconnect for non-pay because you do not have to send a truck to the meter. In addition, our experience showed that within a few hours after disconnection, the customer would pay and need to be reconnected. The switch has to be able to open the customers load up to 200 Amps. So we proposed to install several thousand smart meters with remote disconnect switches. Not every customer needs one. The commission however told us that we needed to have a disconnect at each meter so we ended up doing that. 2,500,000 meters later everyone has a disconnect.

    Example 2: The commission thought it would be great for us to have a Residential Time Of Use (RTOU) rate to give residential customers 'the correct price signal' and thus make them use less energy on peak reducing our need to build generating capacity. This was before deregulation. We did surveys and found out that the only customers that were interested in the rate were those who worked third shift and would save money by doing nothing in the way of changing their usage pattern. The PUC insisted and so we put a rate into place and sure enough only about 10,000 out of 2,000,000 customers participated. Electricity was just too valuable for a customer to be willing to turn his thermostat up when it was ~105 deg F outside.

    I'll stop there for now.
     
  18. nwdiver

    nwdiver Well-Known Member

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    Regulators are supposed to provide balance in a natural monopoly. 'Build and Grow' is the business model of the utility but that's not always in the public interest.

    TOU is a failure... unless it involves no routine intervention on the part of the consumer. If someone can save ~$10/mo by enabling the delayed charging that comes with most EVs they'll do that. Basically for TOU to be effective it needs to be largely automated. But without TOU there's no market for automated systems....
     
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  19. jjrandorin

    jjrandorin Another BMW convert

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    This thread would be a lot more interesting to read without all the snark / snide comments in it. The subject itself is pretty interesting, but the antagonistic posting style of some in it is much less interesting.
     
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  20. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    My car charges at 72 amps, 17.28 kW at 240 volts. Even so 9.6 kW for a longer time is the same problem on the average. It will just be a bit later on the adoption curve when this starts to be a problem for distribution. I can also see a lower charging rate meaning an EV owner being more careful to charge every night.


    Ok, lets work with this number then since the model 3s will be the vast majority of Teslas on the road going forward and I guess it is reasonable to expect most will use the mobile cord on a 14-50 outlet rather than install an HPWC.

    Not sure why you are posting this. The overall demand peak is not of consequence for this discussion. What is important is the load on the residential grid during the residential demand peaks.

    In your area what do they use for backup heat to the heat pump? Where I am it is usually straight electric. That is the issue since straight electric at 15 kW is what will be seen as a load. If the distribution transformers and wiring are sized to the demand of the heat pumps, you can see the distribution grid will already be stressed on cold nights. No?

    Yes, that is exactly my point. But I haven't heard anyone say they size distribution with full knowledge of each home's exact consumption configuration. That also changes. My old house had oil heat. Then an air conditioner was added. Then the AC was replaced with a heat pump. I don't see any indication the transformers have changed in my neighborhood.


    What is the algorithm? How much does it oversize? Whatever that amount is I doubt it allowed for the comparatively large extra capacity needed for EV charging.


    Generation is not the issue. Even if they run a lot of watts, they don't run for hours. They typically run for a few minutes and shut off. When hot water is used they run enough to replace the hot water used. Unless someone takes a shower, that's not so much. Since even in the smaller statistical scale of local distribution running for 5 or 10 minutes is not such a big deal.


    As far as I know generation is deregulated everywhere in the US. But don't assume generation will magically keep up with demand. There are places where deregulation simply means prices increase since a constant shortage of power is in the interest of the generating companies. Not entirely unlike OPEC. Ask someone in California. I understand there are still issues with supply there, especially now that they have so much solar generation which fails every day and supplies nothing in the evening.
     

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