Microgrids and the facilities they server are become a larger topic in the building energy landscape as reliability, resilience, and carbon emission reductions are sought. From research done at GreenTechMedia, ‘GTM Research now tracks over 1,900 basic and advanced, operational and planned microgrids.’

To level the terminology playing field, a microgrid is a building or collection of buildings, capable of operating on their own power system and power source, independently while being smart enough to automate this process and provide a level of energy management, to reduce energy use and manage energy sources. The folks at LBNL have a more technical definition as well which is good to read.

There are many microgrids in existence and most utilize some form of backup power with diesel or fuel oil. This makes sense, most installations revolve around reliability and uptime, yet what if we could do the same function only 100% clean resources?

We are seeing some amazing hybrid approaches coming online and many owners have now started to consider solar+storage as a way to stretch fuel supplies longer, taking what might have been a weeks worth of fuel and potentially now spanning a month. Shown here is a thought diagram I made on how a building today with a microgrid using a generator and fuel set could start to incorporate pv on site and eventually PV_ battery storage, stretching their fuel supply to be able to ride through longer duration.

From MicrogridKowledge.comLiberty Utilities has begun exploring a utility microgrid in the North Tahoe region of California that would use up to 8 MW of Tesla batteries.’

Looking forward, both with net zero energy buildings becoming popular and the long term trend toward decarbonization, I would like to coin a term of Renewable Microgrids, able to meet the reliability and resilience targets while finding pathways to low carbon, financially sound solutions. These systems can be compared based on their level of renewable energy mix and how long they are able to run in days and weeks. To compare microgrids, I propose developing metrics of days of operation at a level of full normal power and a percentage of this function provided by renewables.

To even dive into metrics, it is important to address the scales of what a microgrid could be. I have developed three scales of renewable microgrids; Building, Campus, and District or Community Microgrids. While the technology might be similar, the scale of these three will radically change the business models and deployment strategies for microgrids. Some systems may be in a single buildings, while others could span a campus (like the ski resort in tahoe) or be a small utility or municipal service provider.

Build Environment Scales for Microgrid

Building Microgrids

Individual buildings, such as hospitals, critical facilities, laboratories and large offices who have the ability to automatically operate as independent energy systems on their own energy sources and provide a way to manage this energy smartly. Many facilities like this operate for reliability. A microgrid will often be devised to know how to not just operate but how to manage energy use, turning off non critical systems automatically, and provide a means to manage generation.

Campus Microgrids

A campus consists of many buildings which could be a corporate office park or a college university. Any collection of buildings on one developed site, undivided by public access. Campuses often are able to leverage a microgrid as the brain and tool for managing other shared resources or utilities. A campus can often benefit from shared thermal energy in hot or cold water and can share in the cost of a microgrid system. Much of the work in campuses looks at developing systems that can provide flexibility for both the unknowns and the knowns. Campuses can find multiple benefits in future planning and future demand growth management with a microgrid for instance.

[District] Community Microgrids

A district microgrid is a larger region or neighborhood area, were microgrid services and ability to maintain energy and operations is provided to a host of participants. Many of these are created by or in partnership with utilities, helping to provide larger regional benefits to a neighborhood while helping a utility manage the grid and smooth operations. Many of these projects focus on working with the agencies and utility partners to find the right set of solutions.

Must be Beyond Backup Generators

Not all backup generators can switch from grid energy to independent operations. Some can though this is a fundamental feature of a microgrid. A microgrid is also a system that when running in normal operations can provide services back to the grid, such as managing peak power demands or storing energy when needed.

A Platform for Smart Grid Technologies / Grid Edge Technologies

As energy systems continue to evolve, another area of focus is with smart grids and grid edge services. Many of these can overlap with a microgrid though fundamentally focus on different areas of need. Smart grid services tend to focus on ways to get the grid back on line in-case of power outages, or ways to better manage fluctuations in energy needs and power quality on the energy grid. Leading utilities who have deployed smart meters are often able to better establish were a grid fault is and get the lights back on faster, working with a smarter grid. A microgrid tends to focus on how to maintain and create reliability in the face of changes in a larger electric grid. A microgrid is focused on keeping the lights on, no matter what for the buildings it serves. So while they are related, it is good to keep these as separate discussions and understand they can compliment each other though the implementation could come from two different parties.

My question to you: do you think 100% renewable microgrids are possible? And do you have any success stories at a scale size we can broadcast! I would love some input on a metric and if this comparison would help.