Reconstruction of Infrastructure
Think about the car as an energy source (Part 2)
Second installment: Connecting EV or PHEV batteries to households
Using EV in a ‘cluster’
On the other hand, in December 2012, Nissan Motors have already launched their mass produced EV ‘Leaf’ and are conducting experiments using it. The company wants to use EV in a ‘cluster’, rather than only linking it to one household. ‘70% of the cars worldwide are in a parked state’ (Nissan Motors). Hence, by exchanging the power with such parked EVs, it will be possible to bring about power stability not just for households, but also for the buildings and communities. Moreover, Nissan thinks that it is possible to recycle the exhausted batteries of an EV. For this, it has established a joint venture ‘4R Energy’ with Sumitomo Corporation in September 2010.
Although Toyota Motors and Nissan Motors are taking respective efforts, as automobile manufacturers, they both agree on one common point - the amount of power taken from 1 vehicle should not be too big.
If a large amount of power is stored and withdrawn repeatedly from one particular vehicle, it leads to early depletion of the batteries. Moreover, if the user wants to urgently use the vehicle, the whole purpose of an EV might be defeated as it will not give the expected mileage. Hence, Toyota Motors think that ‘only a small amount of power should be used for household purpose’, while Nissan Motors are of the opinion that ‘many a little makes a mickle.’
EV can help reduce household power consumption
Nevertheless, that such efforts were already being taken even before the earthquake is certainly an encouraging thing; as in the wake of the post-disaster power shortage, the idea of utilizing PHEV and EV seem to be realistic.
Actually at the time of power shortage in summer, it is very much desirable to reduce the peak power consumption by households, offices and enterprises by 15%. Let us consider this for one household. If the peak power consumption for one household for 1 hour is estimated as 2kWh, 15% translates into 300Wh. To reduce this much amount over 6 hours, it will be sufficient to get about 1.8kWh power from the vehicle. If we have an EV like Leaf, which is equipped with a battery of 24kWh, then using just 7.5% of the battery capacity would be enough. This sounds to be a possible solution then.
On the other hand, in case of a PHEV, as the battery capacity is 5kWh at the most, for the power supply of 6 hours, it would require 36% of the total battery capacity. Hence, it would be difficult to rely only on the battery in case of a PHEV. However, PHEV come with a big generator (motor) along with the engine. Hence the lacking part could be covered up by using the power generated from the engine.
Thus, connecting the batteries of EV and PHEV to households is certainly a worthwhile initiative. In fact, the Ministry of Economy, Trade and Industry and the Automobile Industry held an ‘Automobile Strategy Research Conference’ on May 19, 2011 and have recently started a study regarding using batteries installed in EV etc. to reduce the power consumption during peak hours in summer. (To be continued)