Our nation's industrialization and subsequent use of fossil fuels has given our society access to a switchable utility system. That is, when steam engine train conductors or coal plant operators wished to alter a supply of energy, they could simply add fuels to burn and convert to energy at any time they wished. Because of this, our electric grid is designed to simply deliver peak-load supply, i.e. the grid is built to have the necessary capacity for the maximum energy use on a hot day in the summer. If users are pulling more Watts from the system, grid operators can just switch the system to deliver more Amperes.
Renewable generation technologies including photovoltaic (PV) modules and wind turbines do not follow this model. These sources of energy cannot be controlled such as those provided by fossil fuels. These sources require the sun to shine and the wind to blow, respectively. For grid operators, increasing the use of these sources adds undesirable fluctuations of available energy. This is especially true for localized distributed generation sources such as solar panels on residential homes. Connecting these sources to the grid changes the makeup of the grid in unpredictable ways that make grid operators unable to properly evaluate system load requirements and locate system faults. Additionally, energy consumers cannot be expected to utilize renewable generation at the instant it is most abundant. Consumers are unlikely to dim their lights until the sun is bright or to complete their most power intensive computing when an impeding storm causes high wind speeds. Clearly, our electric grid will need to be updated in order to use more renewable energy.
Vehicle-to-Grid (V2G) technology is one possible way researchers hope to improve the stability and reliability of our grid when incorporating renewable generation. The idea, originating from University of Delaware Professor Willett Kempton, is that the electrification of our transportation fleet goes hand-in-hand with the inclusion of renewable energy in our grid. He and other researchers argue that the Lithium-ion batteries on fully electric and partially electric vehicles can be used to temporarily store and redistribute energy to and from the grid. This means that your future Prius may come with a two-way connection to the grid. Professor Kempton argues that because 95% of vehicles are parked at any given time, a significant number of electric vehicles could potentially end reliable concerns of variable energy supplies.
An analogy with a different technology that you are using as you read this post may help illustrate how this works. Imagine that our information superhighway was changed to where there was no storage involved. Each bit and byte had to be available at all times so it could be delivered instantaneously upon request by the consumer. This is how our energy system works today. However, due to Internet protocols and storage technology, we do not have those requirements. As you access this post you are utilizing storage components within the Internet structure, and as you read this post you are utilizing storage on your personal computer. In fact, one crucial component of a V2G system is information technology that tells the grid when and where to pull and deliver energy.
The city of Newark, Delaware, is now testing a demo V2G system. Professor Kempton envisions a situation where consumers will be compensated by energy companies to enable V2G to pull from their vehicles. The Smart Meters necessary for V2G could also be used to give energy prices that correspond to the demand. This would encourage the public to buy into V2G systems because they could opt to sell energy when the price was highest.
Of course, problems still need to be clarified and researched further including the impact of V2G on the life-cycle on the Lithium-Ion batteries currently installed on electric vehicles. However, hope is increasing for V2G as politicians accept the need to modernize our electric grid as we increase our use of renewable energy.