What’s the Difference Between a Microgrid and Simple Back-up Power?

When we are out in the field talking to customers, we often find there is significant confusion between the terms “back-up power” and “microgrid.” So, we figured it would make sense to discuss each of these and clarify the significant differences so that you can determine which of these may be best for your organization.???????????????????????????????????????

What is back-up power?

The Department of Energy defines a back-up power source as a “power source used to supply electrical power when the normal source is unavailable.” Put in simple terms, when the grid goes down, back-up power is the temporary resource that keeps your operation up and running until the lights come back on.?

Back-up power resources serve critical loads for organizations that simply cannot afford to go without a supply of electricity. Facilities such as factories, grocery stores, data centers, and hospitals often face extreme challenges in the event of power disruptions, ranging from extremely high economic costs to potential loss of life. To take just one example, a 2021 survey of data centers found that 40% of power outages in that industry resulted in costs ranging from $100,000 to $1 million, while about 17% of outages exceed the $1 million thresholds.?

While not all blackouts may not be that costly, they have unfortunately been increasing in recent years. The U.S. Energy Information Administration reported recently that 2020 was the worst year in the 13 years they’ve been tracking such things, with U.S. customers experiencing slightly over eight hours of electric power cuts. The result of this degradation in reliable supply has been a generally increasing reliance on back-up power (and microgrids – but we will get to those later).?

A typical back-up power system consists of an emergency power source, a means of delivering energy from that source to load, and – in many cases – a way of isolating only essential end uses (such as those vitally important servers in a data center or life safety systems in a hospital that allow for continuity of critical missions). Such emergency back-up systems aren’t designed to be run continuously.?

With all the news out there about fuel cells, batteries, and on-site gas generators, one might be forgiven for thinking that diesel back-up generators are a thing of the past, but that is unfortunately not the case. Even in a state such as California, with its strict air quality standards, the fact is that an increasingly brittle grid has resulted in a recent jump in the use of diesel back-up power. ?

In fact, a 2021 study showed that 90% of California’s emergency generators are supplied by diesel, creating a significant health hazard (estimated at nearly $136 million in yearly health costs) and a growing impediment to achieving the state’s greenhouse gas reduction targets. Worse yet, the population of diesel generation in California’s Los Angeles and Bay Area has soared in recent years. Diesel generators release not only carbon dioxide, but also a host of other nasties such as particulate matter, volatile organic compounds, nitrous oxides, and sulfur dioxide – all of which contribute to smog and breathing difficulties. These systems will face increasing pressure to get much cleaner in the years to come.?

Air quality is an increasing issue with back-up generators

https://www.bloomenergy.com

Microgrids – a whole lot more than just back-up power

Microgrids are also designed to serve critical missions without interruption but are more sophisticated than your typical back-up power resource. A typical microgrid is really a controllable miniature grid – nested within the larger power grid – that serves a number of interconnected loads that may be located in multiple facilities. They also tend to be much cleaner, with more renewable and energy storage resources integrated into the supply network. Many do have some type of fossil-fired local generator to complement renewables (in some cases including those dreaded diesel generators), and they are often capable of running continuously for extended periods.?

The appeal of “islanding”

https://www.outsideonline.com?

Finally, a critical distinction is that a microgrid is usually connected to the grid but can “island” off to function on its own when desired or necessary. Many microgrids are capable of exporting power and other services (such as grid balancing) when connected to the grid. As noted in our previous post on load controllers, the intelligence embedded into these systems far exceeds that of a back-up power arrangement. Sophisticated controllers can manage a variety of supply and demand resources and monitor data coming in from the grid, such as power quality and – in some cases – even power prices.?

Action items:??

1.?????Evaluate the exposure of your operations to power cuts, in terms of frequency, economic costs, and other risks to your organization?

2.?????Determine whether you need a simple emergency back-up power system (be sure to evaluate potential emissions environmental considerations) or whether a microgrid may best suit your evolving electricity supply needs?

Continuously yours,???

Matt Ward and Joyce Bone – Founders, SolMicroGrid?