Saturday, June 6, 2009

Plug-in Transportation, Can the Grid Take It?

The boom of plug-in transportation is coming. In late 2010, GM plans to sell the Chevy Volt. Nissan, Toyota, BMW, & Mercedes will be in the plug-in game too. So what is going to happen when all these plug-in cars hit the road? Will the electricity grid collapse? Will coal plants turn the knob to 11 and choke us all to death?

You can rest assured that the grid will not collapse. Well, at least not due to plug-in cars.

The grid expands as needed. After WWII when air conditioners grew in popularity, the grid did not collapse. In the '90s when computers erupted across the country, the grid held up. In this decade, big screen TVs filled living rooms and home theaters across the country without resulting in massive outages.

The big switch to Digital Television in 2009 is projected to use 250,000 DTV converters; each using 5W when idle. 5 Watts is not much but when you have 250,000 of them they add up to over 1 megawatt of constant load added to the grid. That is over 10 thousand megawatt hours annually: a new power plant in itself.

You can see in the chart on the left that utilities are planning for the future with projections of electricity needs as far out as the year 2050.

In 2020, plug-in cars a projected to be less than one 30th of the grid's overall load. And in 2050, plug-in vehicles are projected to be only about 2,000 of the 46,000 Megawatts. Even in 2050, plug-in vehicles are not the major grid load that EV-haters paint them to be.

If all these plug-in cars are coming out in 2010, how could the energy demand be so small in 2020?

The Toyota Prius was first sold in the US in 2001. In 2007, hybrids only accounted for 4.8% of the vehicles on US roadways. J.D. Power predicts that in 2015, hybrid cars will be up to just 7% of the US fleet.

Even with incentives, plug-in hybrids will likely have a higher initial sticker price than their non-plug-in counter parts. Meaning the adoption rate for plug-ins could be even slower than it was for no-plug-hybrids.

One question down: Will plug-ins cause the electricity grid to collapse? Answer: No, plug-in growth will be gradual and the grid will be undergoing planned supply growth.

On to the next question: Will coal plants turn the knob to 11 and choke us all to death? David R. Baker, SF Chronicle Staff Writer, seems convinced "[electric vehicles] will increase the demand for electricity, much of which will probably come from new coal-fired power plants".

Studies have shown that by smart charging, the existing United States electricity grid can support 160 million electric vehicles without building a single new power plant!

It's true that electrified transportation would add to the demand for electric power, but the impact would be mitigated if the cars were recharged at home at night. Unlike a DTV converter that runs 24x7, plug-in cars can place their demand on the grid at off peak times. A 2006 U.S. Department of Energy study found that if all the cars and light trucks in the nation switched from oil-based fuels to electricity, the available, overnight generating capacity of our current grid could recharge 84% of the current US fleet.

Dr. Michael Kinter-Meyer, a scientist at Battelle Pacific Northwest Laboratory in Richland, Washington, said the lab's research suggests that between 43% and 73% of all cars and light trucks in the nation today could be replaced by plug-in vehicles without adding new power plants or transmission lines, provided much of the recharging took place at night during low electric demand periods.

Why is there surplus energy at night? The electrical grid must be built to handle the worst case load. Think about a parking lot at a mall. The lot has to be big enough for the blitz of shoppers on the day after Thanksgiving, or you are turning customers away. This means that most of the rest of the year, large parts of the parking lot are empty. Similarly, the grid capacity has to handle the peak loads of the day when homes and businesses are active and then because a power plant cannot simply be shut off, they have surplus energy at night. To contrast the "peak" demand time, a period of low demand is referred to as a "valley".

Further increasing the nighttime supply of electricity is the proliferation of wind turbine farms. The winds are often stronger at night. Plug-in cars may be just what is needed to soak up this nighttime surplus of energy. Adding demand to off peak times is called "valley filling" and is shown in red in the figure to the left. This is one part of leveling the demand load and utilities welcome it.

It will take encouragement to make people utilize off peak power. There are several ideas that utilities could use to provide this encouragement listed in the "tools" section below. These include billing for plug-in vehicle electricity separately and exaggerating the on-peak vs off-peak costs compared to regular home electrons. Or even have a midnight to 2AM "charge at no charge" period.

In addition, the existing nighttime electricity can be stored in plug-in vehicles and retrieved during peak-demand hours through vehicle-to-grid (V2G) technology, helping to meet daytime peak needs. This is referred to as "peak shaving" (shown in blue in the figure above) and it further levels the load making it easier for utilities to meet the needs with a more constant supply. V2G is yet unproven but could work well for fleet vehicles. The simpler method of peak shaving is to allow the utilities to turn off charging stations for short periods during peak load. The utility could do rolling 5-minute blackouts of charging stations. This allows them to reduce the load without any significant impact to charging service and is simpler to implement than V2G. This is one of the features that Better Place offers electrical utilities with their charging network.

That answers the final question: Will plug-ins cause coal plants turn the knob to 11 and choke us all to death? Answer: No, the existing grid has more than enough capacity to charge at least 40% of the existing US fleet with smart incentives to encourage off-peak charging. Again, the adoption of plug-in cars will be gradual and it will be a long time before 40% (or even 10%) of the US fleet is plug-in. During that time we can shift to cleaner sustainable power options that cause less environmental harm than fossil fuels.

Oregon is one of several states with initiatives to increase the percentage of electricity that comes from renewable sources. This means that as the power grid is cleaned up, plug-in cars get greener. Once you are plugging in a car and using it for your daily transportation, where that electricity comes from suddenly could matter a little more to you. At one point in time, over half of electric transportation advocacy group Plug-in America's board of directors had solar panels on their homes. My plug-in truck was the tipping point for us to install solar PV panels on our house. If pollution or CO2 is a concern for you, there are options. You can buy renewable power from your utility for only pennies extra per kWh, or you can install your own renewable micro-generator such as PV or a residential wind turbine.

Plug-in transportation does not "just move the pollution from the tailpipe to the smokestack". Even on today's grid, plug-in transportation is about 3X cleaner than gasoline fueled driving. That is why plug-in transportation is endorsed by the WWF, the American Lung Association, and the Sierra Club. Plug-in transportation is an important part of a cleaner future.


Links
California utility prepares for surge in plug-in electric carsMotor Authority: Expert says electric grid ready for plug-in hybridsUser-controlled electricity saved money; stress on power grid

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