Hidden Cost of PHEVs – Part I

A Plug-in electric vehicle will cost at least $10,000 more than a comparable hybrid gasoline-powered vehicle because of the expensive Lithium-ion battery.

This cost is well recognized, and some believe the public will be willing to spend the extra money to reduce their use of gasoline.

But there are hidden costs that need to be considered. Eventually, these costs will be borne by the consumer.

The first of these is the cost of building new power plants to supply the additional electricity needed for recharging batteries.

The second hidden cost is the cost of replacing distribution transformers, and possibly substation transformers, as the charging of batteries increases the load on the transformers.

There is also the cost of disposing of the Lithium-ion battery.

Today, let’s examine the hidden cost of building new power plants.

A study by the Pacific Northwest National Laboratory (PNNL) determined that 73% of the existing cars and light trucks in the lower 48 states, or 158 million vehicles, could be PHEVs before it would be necessary to build new power plants.

The study assumed recharging would take place over a 24-hour period, while in practice, recharging should be limited to around ten off-peak hours, from 8 pm to 6 am. Restricting battery charging to off-peak hours reduces the number of PHEVs before new power plants are needed, to approximately 87 million vehicles.

The PNNL study was based on the fact that the amount of electricity used during each 24-hour day varies hourly, and can be charted as a curve for electricity usage that appears as peaks and valleys.

Essentially, the PNNL study assumed that the valleys could be filled without affecting the peaks. Since charging batteries will require from four to eight hours, charging during the day will almost certainly be done during peak periods.

Utilities build sufficient power plants to meet their peak loads plus an additional reserve of 10%: Peak loads typically occur in the summer afternoon when air conditioners are turned-on, and in winter evenings when lights go on and cooking takes place.

If people can be prevented from charging their batteries during peak periods, it would take at least two decades before new power plants would have to be built. Under this scenario, charging between 10 pm and 6 am, roughly 87 million vehicles could be charged without building new power plants – assuming the vehicles are spread randomly around the country.

The opposite strategy is being pushed by the government and various organizations.

Their strategy is to build charging stations in downtown areas so that people can recharge their batteries away from home – during the day.

If 240-volt charging stations, costing $2,500 each, are used to charge during the day, it is certain that charging will take place during peak periods. Even if people use rapid charging for only an hour, with charging stations that cost at least $25,000, some of the charging will occur during peak periods.

Charging batteries downtown during the day will unquestionably be done during peak periods, and will require building new power plants sooner rather than later.

As soon as charging batteries establishes a new peak using more than a few percent of the 10% reserve, the utility has to build a new power plant.

The government’s strategy of installing charging stations downtown for use during the day, will mean that new power plants will have to be built much sooner than if charging is restricted to off-peak hours.

If charging can be restricted to off-peak hours, it won’t be until there are around 87 million PHEVs on the road before new power plants will have to be built. Based on Pike Research, estimated sales from 2011 through 2015, and using a 30% growth rate thereafter for sales, new power plants would have to be built beginning in about 19 years – sooner, if peak loads are exceeded by charging during the day.

Next Wednesday, in Part 2 of the Hidden Cost of PHEVs, let’s look at how distribution transformers are affected by PHEVs.

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