Quantifying the Value of Renewables-Driven Resilience

A look at how quantifying the value of renewables-driven resilience in a critical load-tiering fashion might help facilitate the proliferation of distributed technologies e.g., solar microgrids

One of the best things about writing this Substack is that, even though I’ve only been doing it since March, I’ve gotten great responses from people in emails, Twitter DMs, and on other websites.

Following my recent energy storage skepticism post, a reader asked me if I had heard of the Clean Coalition’s Value of Resilience (VOR) methodology for scaling energy storage to critical facility loads. I’d never heard of this, but I looked into it. Pretty interesting; the methodology purports to quantify the value of renewables-driven resilience “at any facility type, in any location.”

As an aside, there’s often confusion, among myself and many others, as to what differentiates resilience from reliability. A 2017 Greentech Media piece explains that “[r]esilience is a more expansive concept than reliability, encompassing consequences to the electricity system and other critical infrastructure from increasingly likely high-impact external events. Reliability metrics like SAIDI and SAIFI generally make exceptions for extreme weather events when measuring utility performance, whereas resilience is often articulated as a grid attribute that improves the response to such events.”

But back to the Clean Coalition — I’m vaguely aware of this organization; I’ve seen their name in various California regulatory proceedings, but I don’t know much about them. Their website explains that they’re a non-profit organization that strives to remove barriers to the procurement and interconnection of distributed energy resources.

Here’s a brief synopsis of the VOR methodology (more specifically, the “VOR123 Methodology”), per Clean Coalition’s website:

The key to the VOR123 methodology is tiering electricity loads — because different loads have different values. Refrigerators that keep food or medicine from spoiling, communications systems used by first responders, and water systems for fighting fires are life-sustaining and critical to keep online, whereas most loads are highly discretionary with little impact from going offline for periods of time.

The VOR123 methodology categorizes loads into the following three tiers, regardless of facility type or location:

• Tier 1: Critical loads are life-sustaining and/or mission-critical that should be configured for 100% resilience.

• Tier 2: Priority loads should be maintained as long as doing so does not threaten the ability to maintain Tier 1 loads.

• Tier 3: Discretionary loads should be maintained only when doing so does not threaten the ability to maintain Tier 1 and Tier 2 loads.

Facilities vary in the percentage of their total load that is deemed critical and priority. A fire station typically has a far lower critical and priority load percentage than a hospital, for example, but regardless, the key is for each facility to determine for itself what percentage of its total load is critical and priority. While these percentages do vary, the Clean Coalition has found that the majority of facilities have the following approximate load tier percentages:

• Tier 1: Usually about 10% of a facility’s total load.

• Tier 2: Usually about 15% of the total load.

• Tier 3: The remaining load and usually about 75% of the total load.

In short, the methodology claims to provide a way to easily value resilience for any facility, whether provisioned onsite or from community microgrids; this is accomplished by the load-tiering process described above.

PV Magazine, a website I enjoy and appreciate (even though I ribbed them a bit as part of my recent energy storage skepticism post) published a piece in 2020 by Clean Coalition executive director Craig Lewis on the VOR1123 methodology. He wrote:

Ask anyone if there’s value to the resilience provided by indefinite renewables-driven backup power, and they’ll answer, “Of course, yes.” Ask them to quantify this value, and they’ll have no answer. In practice, the result is that renewables-driven resilience has been valued at zero.

Because we lack a value-of-resilience (VOR) standard, the market for microgrids has remained sluggish — despite increased interest in microgrids for resilience due to ever-frequent disasters, including storms, wildfires and now even viral pandemics. Given that resilience is often the main driver for installing a microgrid, we need a way to quantify its value.

I don’t have enough technical acumen to gauge whether the VOR123 methodology is workable but I appreciate the attempt to quantify. I also appreciate getting well-thought-out emails in response to my posts, so I’ll elaborate on other reader emails in another upcoming post. Thanks to everyone who has corresponded so far; that kind of engagement drives my interest in maintaining this Substack.