Modernizing the Grid: Part III

The role of renewable energy in the smart grid

21 October 2013

Much of the renewable energy and natural gas potential in the United States is located in areas that are remote from population centers, lack high demand for energy, and are not well-connected to our national infrastructure for transmission of bulk electrical power. The recent expansion of natural gas production in the country has also affected development of the grid.

To achieve sufficient transmission capacity, public policy objectives must link new natural gas generating plants, on-shore or off-shore wind farms, solar plants, and other renewables to customers if those resources are to serve the energy needs of homes and businesses.  

New transmission opportunities will play a critical role transforming the electric grid to accommodate the retirement of older generation resources, increase transfer capability to obtain greater market efficiency for the benefit of consumers, and continue to meet evolving national, regional, and local reliability standards. With a stronger and smarter grid, 40 percent of electricity in the United States can come from wind by 2030.

New types of generation and new uses of electricity are creating both challenges and opportunities. Examples of new generation types include wind and solar, both of which vary in output and predictability.

An example of a technology that serves both as an electricity use (load) and as an electricity source is energy storage. It affords the opportunity to compensate for varying grid conditions by providing or absorbing energy to help correct system voltage or frequency. Placing an energy storage device in the distribution grid to serve as both a load and as a distributed energy resource (DER) also offers new integration challenges and opportunities for increased reliability. The electric vehicle, for example, presents challenges in minimizing the grid impact of its charging and also in the opportunity for its use as a DER.

Another technology that has received renewed interest is direct current (DC), especially in localized grids called “microgrids.” For example, solar photovoltaic produces DC, batteries store DC, and loads such as computer equipment and variable speed motors operate on DC. The grid operates mainly on alternating current (AC), and conversions need to take place between AC and DC to interconnect DC generation or loads to the AC grid. 

Efficiency considerations suggest minimizing the number of such individual conversions, leading to exploring new concepts for managing electricity at locations involving these generation sources, storage methods, and loads. Next, local electricity generation, storage, and distribution systems should be improved to increase the self-sufficiency of end users. Longer-term, flow-directing technologies could be added to address fluctuations and differences between energy supply and demand. Electricity might be redirected at times of peak load, for example.

Cost-effective solutions will vary by region, utility, and the equipment and threats to it. In the case of Hurricane Sandy that struck the U.S. East Coast last October, coastal areas that were subject to storm surges and flooding might need underground substations. Inland, where high winds and lashing rain produced the most damage, overhead lines could be buried.

This article is the third in a series on “Modernizing the Grid.” The next post will discuss the “self-healing” powers of the grid. Follow us @IEEEInstituteFacebook, or sign up for our E-newsletter to get notified of upcoming posts.

Massoud_Amin Photo: Massoud Amin

Massoud Amin is an IEEE senior member and the director of the University of Minnesota’s Technological Leadership Institute, in Minneapolis, where he is also a professor of electrical and computer engineering. He is chair of the IEEE Control Systems Society’s Technical Committee on Smart Grids, and serves as chairman of the IEEE Smart Grid Newsletter.


Top Photo: iStockphoto

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