Pull electricity from a Toyota Prius Plug-in to a McMansion, and the lights may go out within a matter of a couple of hours. For a typical Japanese house, though, you'd be taken care of for the better part of a week.

Toyota said it will start testing a vehicle-to-home (V2H) system with the Prius Plug-in in Japan by the end of the year. The trial will involve a two-way power-supply system in which the car could supply the home with power in the event of a black-out. About 10 Toyota City homes will be involved in the testing.

The Japanese automaker says a fully-charged, filled-up Prius Plug-In can supply a typical Japanese house with 10 kilowatts, or enough for about four days. In addition to supplying power to blacked-out homes, the car will eventually be able to power up emergency shelters and other buildings.

Last August, Nissan started testing a similar system with its battery-electric Leaf, which the automaker said could provide about two days electricity for an average Japanese home when the car is fully charged. Nissan said it intended to commercialize the system, but didn't provide further details.
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TMC Develops Mutual Power Supply System for Electric Vehicles and Homes
Tests to Start in Toyota City at End of 2012

Toyota City, Japan, June 4, 2012-Toyota Motor Corporation (TMC) announces that it has developed a vehicle to home1 (V2H) system for the mutual sharing of power between electric-powered vehicles, such as plug-in hybrid vehicles (PHVs) and electric vehicles (EVs), and homes. The V2H system is to start testing, using Prius PHVs, at the end of 2012 in approximately ten households as part of the Toyota City Low-Carbon Verification Project2 (Toyota City Project) that began in April 2010.

The newly developed V2H two-way electric power supply system can supply power from home to vehicle as well as from vehicle to home. An AC100 V inverter onboard the Prius PHV converts stored power into AC suitable for home use, while power flow is controlled according to communication between vehicle, charging stand and the home. With this new method, low-carbon electricity ("green" electricity) generated from regional or home solar generators, or low-cost late night electricity, can be stored in a vehicle's drive battery and then used to supply power to the household during peak consumption times. This kind of optimal energy flow can be automatically controlled by a home energy management system (HEMS).

Vehicle batteries can also be used as a power source in times of emergency by manually setting the electricity flow to supply power from the vehicle's drive battery through the charging stand to a home's lights and power outlets. With a fully charged battery and full tank of gasoline, a Prius PHV can supply power for average Japanese household electricity use (approximately 10 kWh) for four days.

Interest in smart grid technology and expectations for the effective use of electric vehicle batteries has increased due to recent anticipated electricity shortages in Japan, the beginning of full-scale renewable energy introduction and an increased need for emergency power supplies.

Households participating in the verification tests in Toyota City will use Prius PHVs, which can use the V2H system to supply electric power to homes, as well as function as conventional gasoline-electric hybrid vehicles once onboard electricity supply depletes to a certain level.

TMC developed its V2H system while closely complying with existing charging and communications specifications defined by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), as well as with electrical safety standards and regulations. Going forward, TMC hopes to promote the widespread use of V2H systems while closely studying-conscious of standardization trends-system, hardware, power generation and other relevant specification standards.

In addition to the V2H system, TMC has also developed devices capable of supplying electricity from PHVs directly to home devices, for use at emergency shelters in the event of a disaster. The devices will be installed on the PHVs used in this round of the Toyota City Project tests.

The Toyota City Project awards eco-points to consumers who change their lifestyle habits to conserve electricity, and in 2011 there was an increasing trend toward households to use low-cost power to charge their vehicles. In light of the recent power supply shortages in Japan, the Toyota City Project is working to promote regional energy management that can respond to shifts in peak usage. In response to the increasing need to control peak electricity use, the Toyota City Project will test synchronized automatic control between HEMS and regional energy data management systems (EDMS) this year. Existing energy usage optimization technology using household storage batteries will be expanded to V2H systems, making green electricity use even more effective while promoting a shift away from electric power consumption during peak-demand times.

Through the development of the V2H system, TMC aims to contribute to low-carbon and energy-efficient electricity use and to support the Toyota City Project's goal of regional energy independence.

Energy management with the V2H system

1Charging of PHV and EV batteries from household electricity and supplying electric power from onboard automobile storage batteries to the home
2Part of the Next-Generation Energy and Social System Demonstration project (a five-year project running from 2010 to 2014) of the Japanese Ministry of Economy, Trade and Industry (METI) with the aim of optimizing energy on a regional and community level through citizen-led initiatives. Construction of test model homes was completed in June 2011, with the first group of residents taking residence in September. As of May 31, 2012, approximately 40 households are living on the premises.


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    • 1 Second Ago
  • 30 Comments
      • 2 Years Ago
      This would be A Good Thing (tm) for everyone, everywhere. Of course installing the grid intertie is the most expensive part of the deal... but if you can afford a prius...
      Letstakeawalk
      • 2 Years Ago
      It's not really the battery in the Prius that will provide the long-term power, they're talking about using the ICE as a generator. "... filled-up Prius..." being the key phrase. That battery will be depleted rather quickly, but the energy in the gasoline will last a bit longer.
      Anderlan
      • 2 Years Ago
      A Prius provides 4.4kwh (sounds about right for the production Prius plugin hybrid), good for 4 days, but a Leaf with 24kwh, is only good for 2 days? Very different power usage assumptions are going into those two very different estimates. I could stretch 4.4kwh over four days if I were hyper-homing. 24kwh over 2 days is easy, though.
        • 2 Years Ago
        @Anderlan
        Prius has a tank full of dinosaur juice.
      Smoking_dude
      • 2 Years Ago
      Why not, I like the concept. But I really wonder why ppl here want to use their dryers and laundry machines in case of an blackout. So the green autoblog readers want to use their 60" PLASMA and xbox 360 in case of a blackout? LOL I would use my 3kw propane stove for cooking and run only important appliances like lighting a small TV and radio, and the fridge (with timer) of it.
        Letstakeawalk
        • 2 Years Ago
        @Smoking_dude
        If you've ever been in an emergency power-outage situation, you would have a lot more sympathy for those of us who prefer clean clothing, towels, bedding, etc. http://www.tide.com/en-US/loads-of-hope/index.jspx
      Spec
      • 2 Years Ago
      Yeah, that 4KWH battery will run your home for a whole . . . few hours.
        Actionable Mango
        • 2 Years Ago
        @Spec
        We're not talking about every family member playing Xbox on a 60" plasma in separate rooms. In a power outage having just the fridge circuit and occasional lighting here and there, and power for the furnace blower is WAY WAY better than nothing at all.
          Ernie Dunbar
          • 2 Years Ago
          @Actionable Mango
          Indeed. I prefer emergency lighting over candles, thankyouverymuch.
          Letstakeawalk
          • 2 Years Ago
          @Actionable Mango
          Even running just the furnace blower and the fridge, you're not going to make it through the night.
      2 Wheeled Menace
      • 2 Years Ago
      What eco-champions those Japanese are.. with houses that only draw watts in the tens.
        Smoking_dude
        • 2 Years Ago
        @2 Wheeled Menace
        In Japan this is normal, they have frugal appliances everywhere. Even coffee machines have ratings. In Germany ppl give a crap about it, but then they complain about the bill. I switched all lightning to LED and CCFL, which saved me a truckload of money.
      A Middle American
      • 2 Years Ago
      A dedicated natural gas/LP home standby generator would give you all the power you need for a whole house for as long as you need it, and it would cost less than probably just the home battery and inverter setup they have here, let alone the extra cost of a plug in hybrid over non plugin.
      Rotation
      • 2 Years Ago
      10kWh is not enough power for a house for 4 days. 10kWh is about $1.40 worth of electricity. Is your electric bill really $11.20 (8*$1.40) for a month? Nope, mine neither. I am rather frugal and I use over 300kWh per month.
      Joeviocoe
      • 2 Years Ago
      Just make sure you open the garage door :)
        skierpage
        • 2 Years Ago
        @Joeviocoe
        "What happened, I thought you were gonna kill yourself." "I tried, went to sleep in my mom's car in the garage with the engine turned on... Freakin' hybrids, man. They just don't do the trick anymore." -- Kyle and Eric Cartman on South Park
        Dave
        • 2 Years Ago
        @Joeviocoe
        "Carbon monoxide poisoning is the most common type of fatal poisoning in many countries. Historically, it was also commonly used as a method to commit suicide, usually by deliberately inhaling the exhaust fumes of a running car engine. Modern cars with electronically controlled combustion and catalytic converters produce so little carbon monoxide that this is much less viable." http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning
      GeorgeS
      • 2 Years Ago
      The Japanese would not have to worry about power outages if they just were smart enough to start up their nuclear power plants again.
        Dave
        • 2 Years Ago
        @GeorgeS
        I believe the future belongs to nuclear power. But I don't think nuclear power will prevent trees from falling on wires or cars from hitting poles.
      brotherkenny4
      • 2 Years Ago
      "Last August, Nissan started testing a similar system with its battery-electric Leaf, which the automaker said could provide about two days electricity for an average Japanese home when the car is fully charged." Which is about 12kWh per day, which would mean 360 kWh per month, or about the same as the famously frugel Mr. Rotation. The toyota testing probably assumes only a maintainance/backup mode of operation. Probably for lights and a small refrigerator.
        DaveMart
        • 2 Years Ago
        @brotherkenny4
        It's 40 kwh - 10kwh per day. See further down the thread.
        Rotation
        • 2 Years Ago
        @brotherkenny4
        That seems more reasonable. You might not be able to run your A/C, but you should be able to get by for 12kWh per day in otherwise decent comfort.
          DaveMart
          • 2 Years Ago
          @Rotation
          I run my little flat with all the heating and air conditioning, cooking, fridge freezer, tvs, computers etc on around 0.5kw, 12kwh per day.
          Letstakeawalk
          • 2 Years Ago
          @Rotation
          2100 square feet here. Two adults, one cat. We keep the thermostat around 78F (quite comfy), and this month we averaged 14.73kWh per day. The average outside temp this month was 72F, with 22 days over 80F. Big splurges include lots of laundry (electric dryer), and a solid home theater that gets lots of use. We also have an electric range/oven that gets used daily.
      • 2 Years Ago
      The article has a major error. Someone needs to read the press release again. The article says: "The Japanese automaker says a fully-charged, filled-up Prius Plug-In can supply a typical Japanese house with 10 kilowatts, or enough for about four days." The press release says: "With a fully charged battery and full tank of gasoline, a Prius PHV can supply power for average Japanese household electricity use (approximately 10 kWh) for four days." That would be 40 kWh total (10 kWh per day for 4 days).
        DaveMart
        • 2 Years Ago
        Good catch. They are running the engine, and generating electricity. That's pretty weird, it turns out the ABG article is nonsense. Danny has never done that before!
          Joeviocoe
          • 2 Years Ago
          @DaveMart
          "Danny has never done that before!" +10kw
        Dave
        • 2 Years Ago
        It sounds like the Prius is a pretty inefficient generator. 11.9 gallons only gives you 40 kwh.
          Dave
          • 2 Years Ago
          @Dave
          According to this, one gallon has 33.41 kwh of energy in it. http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent 40kwh / (11.9 gal x 33.41 kwh per gal) = 10% efficient.
          DaveMart
          • 2 Years Ago
          @Dave
          It's probably worse than that, as they seem to be specifying a full battery to start with, so you would run that down first, although presumably only getting around 3kwh out of the ~5kwh pack.
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