V2G technology for electric vehicles to the grid reverse power supply timely

September 23, Palo Alto, California decided to promote the city's electric car. The resolution was sponsored by a local citizen. In the end, the municipal government voted to install a EV EV charging station for each household (pictured). As Tesla's home base, the resolution undoubtedly made rich Palo Alto the first to become a paradise for electric vehicles. But the attendant question is, can Palo Alto's grid survive when tens of thousands of electric cars are being recharged every night? Will it affect the local population?

Interestingly, according to one professor, this will not be a problem at all. On the contrary, some day in the future, the large-scale promotion of electric vehicles will instead make the grid system more stable.

For more than a decade, Willett Kempton, a professor at the University of Delaware, has been studying Vehicle to Grid (V2G) from the vehicle to the grid. If you allow current to flow bidirectionally between the vehicle and the grid, the grid will use the resulting current to solve a whole lot of problems. Kempton completed the entire running system prototype this year, but the result has far-reaching implications. In April of this year, the system utilized 15 Mini Coopers, giving them the proper return of some power to the grid at the right time, at a value of $ 5 a day and more than $ 1,800 a year. This is not a small sum, and can even make up the difference between electric vehicles and fuel-efficient cars.

Why is there such a big value? There is a balance between supply and demand

Required, so as to balance. The frequency of the United States is 60HZ. In order to ensure that the electrical energy is stable at 60HZ, the power grid needs its own many thermal power generators to be switched on and off in time to maintain the stability of the electrical frequency. However, this generator is slow to start, ineffective, and pollutes the environment. The reason is like a car's brakes or emergency start the same. However, all costs incurred by it will eventually be counted on the consumer's head. But if it is replaced by electric vehicles responsible for charging, then this will be a cleaner, fast, efficient and low-cost way.

"The only thing you have to do is put some electricity in while charging, just not much, but the benefits are obvious," said Tom Gage. He is the EV grid (the simple electric car charging station in Palo Alto is their home) CEO. The company was founded in 2007. At that time, Gage realized that the popularization of electric vehicles would be a general trend, and the accompanying battery-powered system must be profitable. Prior to that, Gage was CEO of AC Propulsion. AC Propulsion is the ancestor of electric vehicles, the core technology of modern electric vehicles and ACProsulsion blood inheritance, including Tesla. The company also worked with Professor Kempton for many years to develop V2G. Until recently, Gage said openly that technology and policies have matured for the massive roll-out of EV charging stations.

However, Gage admits that there are still places where immature. In order to ensure that electric vehicles can reverse the grid power supply, electric vehicles must be installed two-way charger, but now generally not. Moreover, the bidirectional current will always be AC ​​(AC) and DC (DC) to do the conversion, resulting in a lot of loss, affecting the charging efficiency. So both the preconditions are that the utility or energy department must push EV manufacturers to integrate two-way chargers and at the same time have to develop a mechanism to tell the owner when to charge and when to discharge.

To some extent, this is a superstructure war. Gage said utilities are actually fearsome about V2G. They prefer to build their own generators and make up for the difference by raising their charges, and they will not give up. "At AC Propulsion, we joked at one point that we were huddled in two of the largest areas in the world, one in the automotive sector and one in the oil sector, and now we have to add one area of ​​government utility. Of course, the last one is just Piece of cake. "Gage said half-ridiculed.

From this look, to convince the owners of electric vehicles is nothing more anxiety (but also self-deprecating).

"Oh, you actually have to put my battery, I'm not good enough for what to do, and that will speed up my battery drain, which is probably their first reaction for most owners who have heard V2G year after year." Alec Brooks said. He is the CTO of AeroVironment's EV charger business unit. Although Gage, Brooks and other experts agree that some forms of V2G do not actually affect battery life, they also admit it is not yet certain. No one can fully and deeply grasp the matter at this moment. No wonder auto makers will worry about it.

Brooks actually has a nice solution, called "smart charging," sometimes called V1G. This solution does not require special hardware nor does it cause any loss to the battery. The charging device will stop charging only when the grid needs to be lightly loaded, and continue to charge when the grid capacity is sufficient. The V1G charger does not even need to communicate with the grid: A new unit developed by AeroVironment can automatically compensate for changes in grid frequency in less than a second. The key issue here is that the charger must be fast enough to ensure that your car's electricity will reach full capacity the next morning after it has been stopped overnight.

If Brooks's plan is to go, then we do not need to reverse charge the car from the grid, but the problem is that it may require 10 times the charging time. Brooks said, "Compared with V2G, the value created by the owner in V1G can only be used to give you a discount on the electricity bill, but it can not compensate for the difference from the fuel-efficient car to the electric car." So V1G is actually only a transitional solution to V2G . But for most people, they do not see much more to be profitable from V2G. And experts generally agreed with the view that V2G's additional revenue from stabilizing the grid frequency could actually only be allocated to millions of electric car owners. However, if the size of electric vehicles continues to increase, the actual profits of later owners will be less and less. In this case, the technology there is the meaning of existence?

This is where the original inspiration for V2G technology comes back: wind and solar. The strongest solar output is at noon of the day, while wind energy is at night, and both are unpredictable. The grid has similar problems. Due to limited storage space, energy generation and consumption occur best at the same time. Take wind power, when the wind is the most powerful, wind farms can even turn off the machine to avoid wastage. But if millions of EVs are waiting to be recharged every night, there is going to be somewhere to go for renewable energy.

And if these vehicles can communicate with each other and intelligently share energy, the pressure on the grid from peak electricity can be avoided. "It's like a piece of software, and once you get there, the more you use, the better experience you have," Sven Thesen said. He is an industry veteran in the electric car industry and at the same time happens to be the citizen who started the promotion of an electric car charging station in Palo Alto mentioned at the beginning of the article.

Although V1G and V2G now have several small-scale promotion, but Palo Alto may have to wait for some time to usher in a large area coverage. At present, the market size of the two technologies is still small. "The easier path to find than trying to squeeze utilities and power grids is to find a segment where technology is easier to create more value