Swapping Distribution Lines for Microgrids: An Energy Solution for Remote Areas

When it comes to my work with Cushing Terrell’s Infrastructure Group, onsite energy generation projects are some of the most rewarding given their importance in improving safety and reliability and their predominant use of renewables. For the last two years, one of my most interesting projects has been traveling to remote areas of California, working with Pacific Gas and Electric (PG&E) engineers to install microgrid systems as a permanent replacement for overhead distribution lines.

The microgrid project is part of PG&E’s critically important line hardening program and was implemented to increase electric-power reliability while reducing wildfire risk in areas such as the Sierra Nevada mountain range, the Sierra Nevada foothills, and the Central Valley. The program looks at potential spots where, rather than conducting traditional line hardening measures, the utility removes the lines entirely and we install a microgrid at the site of use.

Some Background

As of 2021, California utilities reported that nearly 40,000 miles of bare power lines existed in high fire-risk areas. To mitigate this risk, utilities have relied on Public Safety Power Shutoffs (PSPS) to de-energize lines in regions facing extreme weather. While PSPS events help prevent wildfires, they can be disruptive to the economy and pose life-safety issues for those people without power.

To reduce the need for PSPS events, the state of California directed utilities to identify lines subject to frequent shutoffs and establish fire prevention plans. Traditionally, these plans have included methods such as undergrounding lines, installing insulated lines, and/or vegetation management around bare lines to reduce the probability of fires. These methods, in particular undergrounding lines, tend to be cost- and labor-intensive given the nature of the terrain and, ultimately, these costs impact rate payers.

There’s another option, however, that California utilities have been exploring — a solution not yet implemented at scale in another state — and that’s the use of microgrids to serve customers locally with onsite energy generation.

With a traditional utility grid, electricity is generated at central power plants and transported over long distances. With few redundant paths for energy to be delivered, thousands of users can be left without power if one part of the grid fails, needs to be repaired, or is shut off in an emergency situation. In contrast, a microgrid uses local, distributed energy resources, such as solar, wind, or hydropower, accompanied with battery energy storage.

Projects to Date

PG&E selected the team of Potelco, ELM MicroGrid, and Cushing Terrell to implement several of the utility’s first wave of projects. Cushing Terrell provides 100% of the engineering work, which includes civil, electrical, mechanical, and structural, while Potelco serves as the general contractor and ELM is the BESS and microgrid control manufacturer.

The customers who qualify for the program are at the end of distribution lines that might be three to four miles long. Rather than undergrounding these lines, which can be difficult and expensive in mountainous regions, microgrids serve as a more cost-effective approach. PG&E leases ground from the property owners and then owns, operates, and maintains the microgrid systems on the property.

What property owners experience on a day-to-day basis doesn’t change, but what does change is the power source generating the electricity. Each site features a solar array, battery energy storage system, and backup generator. The backup generator is there in the case of lengthy periods of rain, snow, or cloud cover. Once a project is online with the microgrid, PG&E begins the process of removing the overhead distribution system entirely: the program is 100% off-grid.

With microgrids come a multitude of benefits. Customers avoid public safety shutoffs and can experience peace of mind that they will have safe, reliable energy; the risk of wildfire is reduced with the elimination of overhead lines; and microgrids offer an environmental benefit as they are powered by at least 70% renewable energy.

Each microgrid site features a solar array, battery energy storage system, and backup generator to provide power to customers in the case of lengthy periods of rain, snow, or cloud cover.

What’s Next (and Ongoing)

PG&E has mapped out where there are other customers in areas targeted for line hardening, and those sites will be assessed to determine whether undergrounding the lines or providing microgrids will be the best and most cost-effective option.

With sites currently in operation and others in construction, we also have several in the initial design phase where we visit the sites and determine the location, configuration, and pricing for the microgrid systems. The sites online now are so spread out that they only serve a single point of use, but in this next wave of projects, we’ll be looking at sites where there might be three or four services tied together with a single microgrid.

I look forward to continuing this work with PG&E and our partners, Potelco and ELM, as well as continuing the tradition of my California road trips. The exploration of this part of the country with our team and the PG&E engineers has been very rewarding, from meeting the customers and learning about their lives to camping and hiking in beautiful areas of the West Coast. We have an incredible opportunity with this program to show just what microgrids can do to support our nation’s energy infrastructure, respond to modern-day energy challenges, and ultimately, reduce wildfire risk.