Al, I have been interested in Vehicle to Grid (V2G) since about 2005 when I bought a converted US Electricar S10 from 1994 which was commissioned at Californian PG&E by Wavedriver in 1995 to show and experiment with V2G in a real road-legal EV.
I agree that it will be the challenge to get the majority of EVs to be plugged in (grid-connected) at the moment that the grid needs support and you are also right that the effect on EVs will not be a large charge drained from the EV battery bank (like all the naysayers are so quick to call out - what if I need to go home and my battery is empty? Well, it will not be. You are in control and you set the minimum charge level you need for your needs and the V2G will never let the battery go below that level. In fact, V2G will typically drain very little from the car battery since it is more about stabilizing the grid (short bursts of higher power until the next power plant has ramped up) than that it is about a lot of energy, so no long-term draining of your battery). What I don't agree with is that V2G can actually lower the peak demand from businesses in the same way that it can stabilize the grid and at a minimum the V2G control can avoid raising the peak demand even while plenty EVs are plugged in, simply by throttling the chargers back during the moments of high demand and giving more power when demand falls again, so it is not costing the business extra on their peak power bill to have EVs charging, even when those EVs are not (yet) V2G capable. If the business does invest in V2G capable EVs or installs a fixed battery bank for grid support, then it can actually lower its own peak demand. Earlier in the morning as soon as EVs are plugged in, the demand is usually lower so the EVs can charge full bore until their batteries are above the level that the users have selected as minimum charge level. The, as soon as the business' demand peaks, the EVs (or local battery storage) can be instructed to deliver a certain amount of power back to shave the peak off that local demand by the business. That typically lasts only a short time, seconds or maximum a few minutes because it is often the starting of motors or similar inrush effects that cause the peak. That means that the batteries might lose a few percent of charge at max during those peaks and that energy meeds to be replenished slowly during the periods that the business is not drawing peak power. Since each modern EV is capable of charging in the order of 10kW power, the V2G capability will be in the same order and so a bank of about 10 EVs should be able to shave an unwanted peak of up to 100kW off a business' power bill. That alone might make it worthwhile to invest in V2G chargers for the business and either buy V2G company cars or encourage employees to get V2G capable EVs and allow them to charge at work for free or even give an incentive (money) for the service provided. I understand the concern that V2G might mean more cycles on the battery pack of the vehicle, but seeing that the typical use of V2G is a high power burst of short duration, it is equivalent to a single acceleration and subsequent braking in the normal driving of the car, something that you do hundreds of times during a trip. It is not that each V2G action is a full charge cycle. It uses a small amount of energy from the battery (at higher power) in a range of SoC (State of Charge) where the battery is little affected by the change, so these micro-cycles typically have little effect on the wear of the battery, since battery wear is usually greatest near the ends (min and max) of charge level. V2G will preferably happen at charge levels where the battery is little affected. For example if the minimum charge a driver selects for his V2G EV is 70% to get home and do errands, then the V2G system might first charge the battery to for example 75% and all the V2G interaction in the afternoon might happen at the charge level between that 75% and 70%. Or it might even happen around the 50% charge level because the user has not arrived before the V2G could charge higher but the 70% charge level is only needed by 7PM so between 5 and 7PM there is plenty of time to bring the level from 50 to above 70%. Note that the user of the EV is in control. If he selects that he needs 100% charge level all the time, then the V2G system will never loan energy from his battery, the only thing that the smart grid can do at that time is to optimize how to throttle other users so this user receives his max charge charge power as quickly as possible. It might also mean that he receives a higher power bill than others who select that they need full charge only after a certain time, so the system can look at the price of power and charge only when it can lead to the lowest power bill and if the user selects that he likes a target charge level of 80% but can allow the car to go down to 60% charge level at any time, then the V2G system might charge his vehicle in the morning hours to his desired 80% but use some percent of his charge during the afternoon peaks and if the price drops enough towards the evening to make it worthwhile, he might find his car charged to 80% again by the end of the day. And he might find a surplus on his power bill due to the service provided at the peak rates while charging at low rates. As you can see, there is need for a smart grid including an identification of the EV (or at least the owner) in the same way as today - by using an RFID card to start the V2G charger. But there is also need for communication between car and charger to transfer the user selections and the actual SoC of the car, as well as the desired power flow between charger and car at every instant to utilize the best price of power consumed/generated. I *do* see a good future of V2G simply to utilize a more and more abundant resource (battery power) that is under-utilized at the moment. NOTE that every Leaf with a QC port can participate in V2G if they wished. Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Al Sent: Tuesday, December 31, 2013 7:58 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] EVLN: V2G project pays plugin owners for eating their pack cycle-life V2G is one of those things that theoretically could be done, but is too cumbersome and expensive to actually implement. Remember, V2G is not about peak shaving as much as short term fluctuations. The biggest hurdle I see is the fact that almost all EV's will be sitting at work all day, not connected to the grid. I don't think you are going to find too many businesses putting in banks of high power interconnects for EV's, especially since businesses are charged for peak demand, DOH! Al _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
