By Liz Enbysk

SGN Managing Editor

Fort Collins and its municipal utility – already on an aggressive path with its "FortZED" zero energy initiative – are wrapping up a DOE-funded Renewable and Distributed Systems Integration (RDSI) demonstration project that senior engineer Steve Brunner says "really opened our eyes to what it's going to take."

Brunner is with the Brendle Group, one of seven technical partners on the RDSI project. Brendle  focused on demand side management and project development. 

Before we look at what they did and what they learned, a little background.

Back in 2007, the DOE put out RFPs for RDSI demonstration projects. This was before the U.S. economic downturn and before the Recovery Act.  In 2008, the agency awarded $55 million to nine RDSI projects around the country. Fort Collins received $6.3 million and local entities ponied up another $5.1 million.

The DOE's chief objectives were to demonstrate the use of renewables and distributed energy resources to provide power during peak load periods and to realize at least a 15% reduction in peak load on a distribution feeder or substation.

Brunner says on that last point, the goal in Fort Collins was a more ambitious peak load reduction of 20 to 30 percent – and along the way they learned how difficult that would be to achieve. But that's getting ahead of the story.

Four demo periods, five demo sites

The Fort Collins project got started in 2010 with set up and testing, but 2011 was the demonstration year where they controlled the assets during a series of four demo periods each 2-3 weeks long. The main focus was the air-conditioning dominated summer peak.

There were five demonstration sites that hosted over 30 projects: the City of Fort Collins, Laramore County buildings, Colorado State University  facilities, New Belgium Brewing (an industrial user) and InteGrid Lab.

The assets involved were equally varied, including diesel backup generators, biogas generators, PV, plug-in hybrid vehicles, thermal storage, CHP and HVAC load shedding.

As Brunner says, "It really was a real-world situation as opposed to a laboratory."

And the partner sites were allowed to establish constraints. One example:  A diesel generator outside a greenhouse/classroom at Colorado State couldn't be turned on until after classes ended due to the noise.  The sites were also pretty much in control of deciding if and how much they could comply with requests – for instance, turning off HVAC or a pump for a building fountain.

Cost versus benefit

Running through a series of tests calling on various assets at various times of the day, Brunner says the bottom line consideration was the dollar amount spent per kilowatt saved. They determined that to achieve 5 MW of load reduction you need to enable approximately 10 MW of distributed assets.

"At the end of the day," he says, "load shedding had the lowest cost per kilowatt hour and the greatest environmental benefits." The greatest reduction they were able to realize was 25% (or approximately 2 MW) on a single feeder and a maximum load shed of 550 KW.

Brunner notes that after the project ended some of the sites have been able to save money by controlling assets used in the tests through building automation and a strong incentive from Fort Collins Utilities' rate structure.