levels, modernization would help integrate wind power and reduce the need for spinning reserve.

In addition to intermittency, the location of many renewable resources (remote or distributed) poses a challenge that a modern grid could address better than the current T&D system does. Many high-quality renewable resources, such as wind in the Dakotas and solar resources in the deserts of the Southwest, are located far from population centers. More transmission capacity will be required to bring electricity from these locations to areas of high demand, potentially using technologies such as HVDC transmission. Other low-emission and renewable resources are likely to be used as distributed generation (e.g., natural-gas-fired micro-turbines, small wind turbines, and solar panels on residential and commercial rooftops). The modern grid will enable better integration of these resources by incorporating two-way power flow and smart metering on the distribution system.

Many modern demand-response technologies can be regulated in response to grid conditions. With the implementation of time-of-day pricing, such technologies could allow for more cost-effective and efficient electric power generation (i.e., by running primarily at off-peak times, when the price of electricity is lower and generating capacity of greater efficiency is available).

A modern T&D system can also assist in the integration of BEV (including plug-in hybrids), thus reducing the consumption of petroleum fuels for transportation.49 BEVs could result in an overall decrease in greenhouse gas emissions even though some of the electricity is generated at coal-fired power plants. Rapid growth of BEVs might significantly increase the demand on T&D systems, but this is unlikely before 2020, when the use of advanced meters could enable controlled battery charging. With the addition of such technologies, the impact on the grid could also be small even by 2035.

A modern grid can operate more efficiently, reducing the need for construction of new generators and transmission lines. Approximately 10 percent of the total power produced in the United States is lost in the process of delivering it to the end user. For example, reactive power flow over a transmission line not only increases losses in the transmission line but also significantly reduces the power-carrying capacity of the line; the use of power electronics, however, can reduce such flow of reactive power. In addition, power electronics can reduce losses by shifting power flow to the most advantageous transmission paths and by the use


Plug-in hybrid vehicles are discussed in further detail in Chapter 4.

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