Leaf, the electric car that recharges your office and not only

Nissan Leaf

What? Electric cars don’t exclusively use energy?

Obviously yes, but they swap energy as well, improving, for instance, office consumptions: that’s the experimentation by Nissan in Atsugi (Japan) based on the well-known reversibility properties about electric “machines”.

Electric motors, which work as power unit as well, allow the energy recovery whereby electric cars – as Leaf- improve their autonomy in the urban use despite of traditional cars. The accumulators too can provide and store energy, otherwise impossible with tank filled by fossil fuels. This two-way conversions are easyfor electrical systems that store and release energy smoothly and quickly.

The use of these properties in a “creative” way lead the Nissan to the experimentation of a system where by companies can regularize their electric consumptions due to energy stored in the Nissan Leaf batteries.

They are the business cars used by employees to get the workplace and the “Vehicle-To-Build” system provides 6 charging/discharging lines.
A sophisticated controller leads the system and decides if it has to charge the Leaf or draw energy from their Lithium elements. The controller takes account of the cost of network energy, the charge of the cars (which will have the highest battery level at the time in which they will be used) and the office needs.

During the day and at the rush hours, when the electricity costs are high, a part of office needs are satisfied by cars but when the costs are lower, the flow are reversed and the cars are charged.

The “Vehicle-To-Build” is active since the last July at the offices of Nissan Advanced Technology Center in Atsugi and allowed a reduction of up 25.6kW of power consumption peak, a decrease of approximately 2.5% of the consumption during the rush hours and a savings of about 500,000 yen a year; the cars were always charged at the right time as well.

Even if savings weren’t so high in absolute values, the results are interesting considering that the Leaf cars involved in the test were only six: “regularization” in fact improves whit the increase of their number.

The “Vehicle-To-Build” system comes from the Leaf to Home, designed for a residential use and able to charge the Leaf during the night (at low cost) or by solar panels; when the tariff rises system draws energy from the Leaf. Even in this case you get a balance of energy consumption in order to draw as much power as possible when the costs are convenient; the “buffer” role, in addiction, is very important in case of blackout.

Virtual power plants

These systems are complementary to Energy Storage units, always designed by Nissan, which employ the same accumulators used by Leaf (no longer automotive grade but valid for stationary uses) to store energy – produced, for example, by the photovoltaic during the day – in order to release it during the night or during periods in which prices are more expensive.

When there will be enough electric cars like Leaf (it is the electric vehicle most sold of history with 87,000 units sold), their batteries will contribute to Smart Grid, networks which will produce/swap energy in their hubs as well as draw it from big power plants.
A Siemens engineer told me that the contribution of electric vehicles will be appreciated when their number rises to at least 10% of total number of vehicles: not a little if you consider the slow introduction of electric cars; we’ll see…

Translated by Federica Izzo

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