Japan Wants To Boost the Use of Electric Vehicles as a Power Source During Natural Disasters (qz.com)

Japan, a country which frequently suffers natural calamities such as tsunamis, typhoons, and earthquakes is looking to further harness the power of batteries used in electric vehicles (EVs) during such disasters, local media reports. From a report: Nissan, which produces the Leaf, the world's best-selling EV model, plans to hold an event in March to let people stay overnight in their cars and try using the electricity stored in their car batteries to simulate the experience of being in an emergency, according to Japanese newswire Jiji. A fully charged electric vehicle can supply power to a standard home for up to four days, a Nissan official told the news outlet. The company last year came to an agreement with Tokyo's Nerima Ward and the city of Yokosuka to provide EVs for free in emergency situations. Nerima also last year (link in Japanese) implemented a system whereby owners of EVs would be able to loan their vehicles out for free to those in need during a disaster, and also started using EVs for its fleet of police patrol cars.

Comments

So...

[psergiu]

... implemented a system whereby owners of EVs would be able to loan their vehicles out for free ...

Mandatory or voluntary ?

More than enough power in an EV to do so

[foxalopex]

Not many people realize how much power EVs are capable of. I own a Chevy Volt which is a mixed battery / gas generator type vehicle and so I have a view of exactly what KWatt's I use when I drive around on my dashboard. Your average house rarely exceeds 10 KWatts at peak power use. Travelling on a straight highway uses about 21 Kwatts of power while slow speed urban driving can be as low as 7 Kwatts. Volt's peak battery output is around 107 Kwatts which could easily cover several houses all at once, it's amazing to think that's how much power is used when a car is accelerating. The Volt's gas engine / generator is about 80hp which is way above any of your camping portable generators which are probably a measly 1-4 hp. The issue is how to hook up the house power safely. Volt's primary power line off the battery is about 360v DC with enough amperage to more than put you in the grave. Unless the car maker safely designed a way to tap the system, it's difficult to do.

Re:More than enough power in an EV to do so

[Solandri]

Every time I point this out, the EV advocates mod me down. The Nissan Leaf comes with a 40 kWh battery, approximately 80% of which is usable (32 kWh). Charging efficiency happens to be about 80%, so you need to use about 40 kWh of electricity to top the battery off with 32 kWh.

The average American home uses 10,399 kWh in a year, or about 28.5 kWh per day. (Apparently a typical Japanese home uses a lot less.) So half-charging a Leaf every day (roughly 50 miles/day use) increases household electricity consumption by (20 kWh / 28.5 kWh) = 0.7 = 70%. Since all that additional electricity consumption happens overnight, if every house has an EV then suddenly the peak electricity consumption period switches from mid-day to overnight. And the lower electricity prices people are expecting to pay to recharge their EV evaporates. Moreso if there's significant solar power generation in the grid. Since solar provides electricity only during the day, the electricity during night to charge all these EVs will have to come from generators the power companies can spool up to meet the overnight demand spike. (Storing solar power in batteries for overnight use is not cost-effective unless solar generation exceeds 100% of daytime consumption. It makes no sense to run other power generators during the day just so you can store solar power in batteries for use during the night, when you can just use the solar power directly during the day (avoiding battery losses) and run the other power generators during the night.)

Meaning you're going to be paying the highest electricity rates to charge your EV, not the lowest. Modding me down doesn't change this truth. The same truth that lets your EV battery power your home for more than a day, also means the power pricing peak will invert when every home has an EV charging overnight.

Fukushima

[sims 2]

Back with the fukushima disaster in japan they were raiding the batteries from the cars in the company parking lot to keep the controls and monitor equipment running.

Also 4 days?! I know a EV holds a lot of juice but if it can really run a home with lights and HVAC for days it should already be being sold as a home backup option.

Re:Fukushima

[AmiMoJo]

Average per house consumption in Japan is about 3500kWh/year IIRC, or about 9.5kWh/day. Even the first gen Nissan Leaf can supply that for a couple of days, and the new 62kWh one could easily do 4-5 days. Presumably in an emergency you would try to minimize energy consumption too, so it may actually last a lot longer.

I know, conversion losses blah blah, it's about right.

Might not work as well as they hope

[Solandri]

Most Japanese do not live in single family residences with dedicated garage space. Most live in apartments with shared parking, where is no way to get electricity from "your" EV to "your" home. The buildings are simply not wired up that way. Maybe newer apartments can be wired so an EV charger in your assigned parking slot gets tied in to the meter (and wiring) of your apartment. But that seems like it'd be excessively complicated - I imagine most such chargers will simply tap into the building's main power line, and its dedicated meter is added up with the apartment unit's meter to calculate the monthly power bill.

Unfortunately, this 1:1 transference of electricity from your EV to your home is necessary if you want people to conserve the power to stretch it out through a multi-day power outage. If you turn the electricity into a shared resource, the tragedy of the commons kicks in. And people start using all the electricity they can giving little thought to conserving it. Japanese culture might help counter that (they place a high emphasis on responsibility to society). But one bad apple in the apartment drawing lots of wattage for an AC, water heater, and playing games on his high-end PC could put a significant dent in the available power across all EVs powering the building.

Re:Might not work as well as they hope

[ColaMan]

If they have the real-time metering you could simply shut off apartments that are over the allocated amount.

eg. all the charge (+ discharge) bays are connected to the building grid. There's an issue with outside power, and building management checks the charge on all the vehicles and decides to allocate 10% of the available EV power sources that are above 80% to the building supply.

They then notify the apartment owners that each apartment has X amount of kWh available for the duration of the outage and to limit their consumption accordingly. If the smart meter shows that they're over that, power is cut until the outage is over or building management decide to draw another 10%.

This is a communal system, but you could also make it an individual system which only allows you to draw what you have available in your EV's battery with, say, 2% skimmed off every connected battery for critical building functions.