Nissan Leaf-to-Home

Electric cars could power homes when hurricanes knock out power

One of the envisioned roles for electric cars is providing emergency power when disaster knocks out the power.

This week the 'Frankenstorm', Hurricane Sandy, is pummeling the East Coast with rain and flooding that has killed several people and reportedly 8 million or more people are without power. Last summer during a heat wave, the political comedian Rush Limbaugh ranted against electric cars suggesting that they become useless when the electricity goes out. This is not the first time Limbaugh has been incorrect about (or lied about) electric cars, because in truth some design features in modern electric cars have the goal of using electric cars to act as an emergency power supply to stabilize the electric grid, such that an electric car could be a great resource when the power goes out, rather than a hindrance.

By the way, when the electricity goes out how will gas stations pump gasoline? Won't gasoline cars also become useless pretty quick?

One of the common "what if" portrayals of electric cars is an idea Nissan placed in a Leaf commercial the company began airing last week. The commercial showed the Leaf owner arriving at her home, driving into the garage, plugging a cord into the car, all the lights come on in the house, and the narrator voice saying "What if, one day, [electric cars] could power your house?"

Functionally, the large battery pack on an electric car is electrical storage. The prime purpose of that electricity is to power the car down the road, but it can be used for other purposes.

One of the elements of the Smart Grid is deployment of electrical storage units that serve as a distributed resource for generation of AC power to improve the security and reliability of the electric grid. If the electrical grid needs more power, signals are sent from the grid operators to tap on electricity sources. In the era of the dumb grid those electricity sources are generally fossil fuel power plants, but in the era of the smart grid it could be electricity stored in large grid-connected battery packs. All of the battery companies making batteries for electric cars, are also involved with making electrical storage units for this purpose. Coda Automotive for example is a subsidiary of Coda Holdings, and that company is also the parent of Coda Energy that repurposes battery packs designed for Coda Automotive as electrical storage units. Battery maker A123 Systems (that recently entered bankruptcy proceedings) makes electrical storage units for the smart grid that store 10-20 megawatt-hours per unit.

Does this capability exist today? The vision is not fully implemented but elements of the vision do exist today, but there are many barriers.

The technology that is closest to implementation is the DC Fast Charging systems, because both the CHADEMO and SAE DC Fast Charge systems allow for bidirectional energy flow while an electric car is connected to a charging station. That bidirectional energy flow means that electricity can flow not just from the electrical grid into the car, but from the car to the electrical grid, if needed.

What's different between CHADEMO and SAE DC Fast Charging is the communications protocol governing the bidirectional energy flow. CHADEMO, designed in Japan, uses CANBUS communications for the charging station to communicate with the car, to control charging rate, and to release electricity from the car. The SAE however saw the need to integrate smart grid communications protocols like ZigBee and HomePhy so that the car can directly communicate with the smart grid. While Nissan and GM and other automakers have been battling over CHADEMO versus SAE DC Fast Charging, the proponents of SAE's DC Fast Charging may have a technical reason for preferring their fast charging system over CHADEMO because of tighter integration with the smart grid.

In May 2012, Nissan and Nichicon announced the "LEAF to Home" power supply system, which can supply electricity from batteries onboard in Nissan LEAF electric vehicles (EV) to homes when used with the "EV Power Station" unit developed by Nichicon Corporation. The unit also provides a faster recharge than the standard 3.3 kilowatt charger on-board the Leaf. It is envisioned as a means for home owners to save money on electricity during the day, by charging their Leaf at low night-time electricity rates and then during the day powering their home from the Leaf when day-time electricity is expensive.

The Fully Charged show (Robert Llewellyn) took a look at the "LEAF to Home" unit in a recent episode (see below).

A barrier are laws governing "Interconnect Policy" because generally speaking electricity sources, on the grid, are not cars but big power plants. The existing policies are geared towards big power plants providing power, not cars. Another barrier is the design of charging connectors, and whether the communications protocols supports bidirectional power flow. This appears to still be a matter of study and research.

Share this content.


Sign-up to our email newsletter for daily perspectives on car design, trends, events and news, not found elsewhere.

Comments

Gas stations simply use generators to create the electricity they need to power the station and the pumps. Since they store enough gasoline to run the generator for literally years, they could run off the electric grid pretty much forever. That is how they actually do stay open when there is a power outage. Some close simply for lack of customers. I would be shocked (get it?) if a Nisan Leaf could handle the start-up amperage needed to run a well pump or oil burner. Those both use different voltage by the way. What voltage and amperage does an electric car put out? A cheap, $199.00 generator form Christmas Tree Shop can run a whole house. The gas on board lasts about 4 hours. Then you refil it (after you let it cool for about 15 minutes). I know this first hand. Also, the house needs to be able to accept the electricity from the outside source via a Generac or other tie-in to prevent killing line workers accidentally. That is true of both electric cars as a source or of a gasoline or propane (or diesel) generator. It is pretty funny to think electric cars would add more to a smart grid than gasoline and propane powered generators. Mine is ready right now to tie into a smart grid to put in power I don't need during an outage. Are the electric cars ready? Why not?
Me thinks you are seriously overestimating the capabilities of generators and seriously underestimating the capabilities of electric vehicles. Not sure where you are buying generators but a $199 generator from Home Depot is rated for 1.4 kw continuous load and 2 kw peak load, way way below what is needed to run a house and the peak rating is likely to be overloaded by most high current startup devices including most home AC units. An electric vehicle on the other hand is so overly capable of handling start up loads it's almost funny, for example the Tesla Model S base model can deliver 270kw of power to the motor and the performance model 310kw of power, if you can show me a home appliance with a peak load capacity anywhere near that ill eat humble pie. The Leaf that you were worried about not being able to deliver the peak output that $199 generator can is spec'd to deliver 90kw of power, compared to 2kw the generator can handle...
The generators advertised and stacked up outside Christmas Tree Shop are 2kW units. They certainly can, and do run whole homes during power outages. My home generator is 3kW and could (did actually) run the well pump (before I switched to town water) AND also the furnace at one time. Generac and similar tie-ins have switches (line, off, generator) the home owner uses to run the highest load items one at time. For example, the furnace or the stove. The lights and fridge add very little load, so you can just leave those on. The reason people buy the 2kW units isn't cost or for want of more power. After about 2kW they get sort of heavy and aren't really portable anymore. BTW, the article talks about two things really. One is running a house. I can be convinced an electric car can do this. Just demonstrate it. The other topic is adding electricity to the grid during an outage. I'm an engineer, but it isn't clear to me how that would work. During outages line workers need to be sure that they know all of the possible inputs to the local lines. How would they work on the lines while people input power? The last thing they want is multiple small inputs all over the place. If a homeowner put power to the line while the worker was doing his thing, the worker could be inhjured or killed. That actually does happen when folks sometimes connect their generators themselves without a proper tie-in. It seems to me that what we have here is a $35,000 solution to a $200 problem.
John, of course it's going to have proper grid-tie stuff to satisfy the concerns you're raising.
You have just acknowledged that they can not run an entire house by admitting that using one requires special switching systems to only allow one big consumer to operate at a time. Even then your definition of a big consumer is very low. Many homes with reverse cycle A/C have systems with peak demands of 3-5kw and running demands of 2-3 kw, more on one big ticket item alone then a 1-2kw generator can handle and that's without running anything else including lighting, hot water, refrigeration, cooking, computer and mobile device chargers, radios or TVs. The issue is not total consumption, the average US home uses 31kwh of electricity a day or an average load of 1.3kw which is perfect for a small generator although it would need to be run essentially continuously which most aren't rated to do. The issue is that the consumption is nowhere near uniform, a large chunk of the power is used in a few hours in the late afternoon early evening during which time demand may be upwards of 5-10kw with spikes as high as 10-20kw during cooking, high heating or cooling use etc. what is needed to allow a small generator to power a home is storage to buffer the low but continuous output and allow it to be consumed when it is needed. An electric vehicle can provide transportation and for no extra cost except for a slightly accelerated battery degradation also act as such a buffer. It can also buffer the output of a solar system which would othwise likely be shut down along with the grid, giving you the potential for potentially indefinite power for both domestic use and transportation with an adequately sized solar array and care with power use.
A leaf has a 24kWh battery. Assuming a very frugal 1000W per hour consumption one might have power for about 1 day before the vehicle battery is empty. Now, the vehicle has no energy for tranportation until it can be recharged. A stand alone generator can be refuled (natural gas, petroleum, hydrogen, ???) for longer duration power interruptions. Does it make sense to use a $30K vehicle along with a $5K charging station? Wouldn't a Natural gas powered whole home backup be a easier more practical solution?
The LEAF is a car that is ALSO a source of back-up electricity. Making it a multipurpose appliance not necessarily a one-for-one substitute for a generator.
Damn and I was just about to go out and buy a Leaf to leave in the back shed and not use it except for back up power after the next storm.