The elevator speech regarding the smart grid is simply that it is a communications system overlay on the existing electrical grid to make the electrical grid more controllable and much more efficient in the delivery of energy. The communications systems will be connected to strategically placed sensors throughout all four segments of the electrical grid: generation, transmission, distribution and consumers. That said, there are a number of ways to overlay and integrate a highly reliable communications network with the existing electrical grid to achieve the efficiency and control objectives that are envisioned.
The first and most obvious would be for the electric utilities to build their own dedicated supervisory control and data acquisition (SCADA) networks. Many large utilities are considering such an endeavor and are evaluating the cost in terms of efficiency, security, availability and reliability. The cost (capex and opex) is significant and the schedule would be lengthy for deployment of such a network, however, the security, availability and reliability would be relatively high. Duke Energy, one of the largest utilities in the nation, plans to install over 800,000 smart meters in Indiana in homes and businesses over the next five years and 700,000 smart electric meters plus 450,000 smart gas meters in Ohio in the consumer segment of the electrical grid. The other three segments of the grid must also be equipped with sensors and switching systems in order to detect demand fluctuations or faults and then affect preprogrammed corrective action to redirect the energy resources properly. All of the information generated from the smart meters and grid sensors regarding the energy usage will be used to develop optimization programs. It is estimated that a minimum of 10% to 15% efficiency gain will result without any behavioral modification at the consumer level. Once the energy use data is more fully understood, the utilities may offer tiered pricing plans to incent the consumers to alter their patterns of energy usage to be significantly more efficient.
A less expensive and more realistic alternative to a private SCADA network would be for the grid operators to contract with the existing communications carriers (e.g. AT&T Inc., Verizon Communications Inc., Sprint Nextel Corp. and T-Mobile USA Inc.) to employ existing wireless/wireline connectivity to the sensors and simply deliver the data in a secure mode to the utility owner’s network operations center (NOC) for analysis and disposition. Hundreds of thousands of sensors in a region would transmit periodic status information to the NOC. The data would be processed and analyzed to ensure that, in the event of a catastrophic event, portions of the energy grid could be isolated to prevent a cascading failure.
There are numerous issues that must be sorted out prior to the realization of the benefits of a smart grid, such as microgrid isolation during failure modes; standardization of interfaces and operations systems; integration and forecasting of fluctuating energy sources (wind, solar); and accommodation of future developments like plug-in hybrid electric vehicles (PHEV). However, the most important issue is security of the grid. This is the issue that will keep Steven Chu, Secretary of Energy and the industry experts awake at night for many years to come.
