Developing Microgrids to Provide Resilience for the Grid and the Community

By Daniel Kushner and Aleksi Paaso 

A resilient and sustainable electric grid isn’t just a luxury; it’s the basis of a long-term economy. In Puerto Rico, failure of the grid due to Hurricane Maria has led to a startling loss of life and large-scale emigration as many lost hopes in the economic prospects of the island. The challenges of building a grid that can meet the needs of the communities who rely on it are tremendous, both in terms of cost and implementation. This is especially significant as we simultaneously seek to integrate higher levels of renewable generation in order to make it possible to mitigate the effects of climate change. Fortunately, accomplishing all of these is becoming significantly more possible thanks to microgrid technology.

A microgrid is essentially a small power grid that can connect to the main grid or disconnect from it to keep locally generated power flowing in case of emergency. Microgrids are already in place to increase resilience in parts of Japan and United States, integrating renewable generation in the areas with significant solar and wind availability., as well as providing electricity in parts of the developing world. Building off of this, in the aftermath of disasters such as Hurricane Maria, stakeholders proposed and implemented microgrids to serve communities in Puerto Rico.

The appeal of microgrids during disasters is clear. They make it possible to restore service to any area quickly without having to restore huge parts of the power system. Puerto Rican policy makers have proposed increased investments in microgrids. Their focus has been, understandably, on installing them to provide service in the poorest neighborhoods. This is a worthy direction, but it fails to recognize additional value of installing microgrids in the areas, where people are not served by electric grid but own and use backup generation.

Due to the loss of faith in the electric grid, many middle-class families and businesses in Puerto Rico have purchased and operate backup generation. Today, those resources are used only for individual benefit. Integrating these generation units into microgrids can reduce the cost of electricity for those customers. What’s more, they can serve as islands that make the whole grid more reliable. Designing the grid in this way can also make it easier to interconnect higher amounts of renewable generation including wind and solar.

In the essence, concept of microgrids offers a very different type of value in this context than it does in the areas with more reliable grids, such as in the continental United States. In Illinois, for example, where Commonwealth Edison is installing a 7 MW microgrid, much of the value of a microgrid emanates from its capability to island from the broader grid during emergencies. In the areas with less efficient grids, such as Puerto Rico, microgrids make it possible for customers to reliably participate in and be served by the main electric grid. Assessing the value of microgrids in such an environment requires a deeper appreciation of the value of the electric grid at large. While many residents and businesses can theoretically install enough back-up generation to be self-sufficient, integrating to the grid makes it possible to reduce costs and be more sustainable.

Reduced costs come from the concept of concurrent peak loads. Electrical systems are designed to meet the peak load, or when the users use most electricity, under the assumption that if it can meet the peak load, then it will have no issue meeting the regular load. A customer who relies solely on backup generation must have enough to meet their own peak load, even if they rarely use that much power; otherwise they might lose power exactly when they need it most. By sharing a grid with their neighbors, it becomes possible to own less generation while still meeting everybody’s peak load, because one customer may not use the maximum amount of electricity at the same time their neighbor does. This concept is already being demonstrated on U.S. military bases, where microgrids are found to be a more economical, sustainable, and more resilient option than the backup generation they had used previously.

Interconnecting those homes and businesses to a highly reliable microgrid also makes it possible to support the integration of renewable, low-carbon generation. Without a reliable grid, the energy produced by solar panels installed on one’s property must be either used at precisely the moment it is generated, stored in a battery, or discarded. In many cases, none of these options are viable, economical, or preferred. By interconnecting this generation to a reliable grid, however, allows for it to be more fully and economically utilized.

Installing microgrids to serve areas that already have back-up generation also provides additional benefits to the broader grid. Not only does this approach reduce the cost of installing a reliable grid for everyone, and support sustainability goals, but it also promotes efforts to make the broader grid more reliable because though these microgrids could island, they would typically be connected to the wider grid. When connected, the distributed energy resources within the microgrid could provide ancillary services such as frequency regulation, which would make the entire grid more reliable.

The technical innovation described here is just the beginning. In northern Illinois, ComEd is demonstrating a microgrid cluster, which will allow two electrically adjacent microgrids to share resources, supporting efforts to make the technology even more economical and sustainable. Researchers have also developed the concept of a provisional microgrid, in which a full microgrid could leverage this clustering concept to allow an electrically adjacent area to island even if it might not have sufficient DER.

Implementing this concept would require careful attention to local situations, including the design of a pricing system that fairly compensates the owners of existing generation while also providing a reasonable price for those who need the grid. By doing so, however, it may be possible to dramatically expand access to sustainable, resilient, affordable electricity to an enormous amount of communities across the world by focusing on how technology makes it possible to better utilize what we already have in our homes and businesses. With this foundation, it is possible to ensure that sufficient renewable generation is integrated to the grid to respond to climate change and produce a more sustainable world for us all.

 

 

 For a downloadable copy of October 2019 eNewsletter which includes this article, please visit the IEEE Smart Grid Resource Center.