Developing a Self-Sustaining Microgrid: Q&A with Stone Edge Farm’s Craig Wooster

Stone Edge Farm Microgrid Craig WoosterStone Edge Farm is a 16-acre estate owned by Mac and Leslie McQuown in Sonoma, California, that includes a winery known for producing Cabernet Sauvignon from organically-grown grapes. In 2013, Mac and experienced electrical engineering contractor Craig Wooster embarked on an open-source microgrid project to lower the farm’s carbon footprint.

Since then, the Stone Edge Farm Microgrid has reached a 785-kW capacity that includes solar PV, a microturbine, and a hydrogen fuel cell hive. The system supplies 100% of the farm’s internal load and produces fuel for three hydrogen-powered cars.

In early October 2017, wildfires raged in the area. “We had built a number of use cases for events that might affect the Microgrid, but none covered a fire assault on the Sonoma Valley or our project,” says Craig Wooster, Microgrid project manager and head of the intern program.

Recently we caught up with Wooster to find out about Stone Edge Farm’s energy strategy and how it helped the estate survive a literal trial by fire.

How did the Microgrid get started?

The impetus was the construction of an outdoor kitchen that was to have large electrical loads. Stone Edge Farm had seven service meters and this addition would make eight. I said the last thing we needed was another meter and suggested looking at energy management or perhaps building a microgrid.

What is Stone Edge Farm’s approach to energy?

Mac is a results-oriented person. It actually says in my contract, “Failure is the crucible of success. You must fail to learn. You will not fear failure.” We said early on that we would entertain new technologies. They had to be at proof-of-concept, alpha model or better so that put us in the beta-test mode.

We had successes and failures. Failures fall into two categories. One was complete failure of a given concept. The second was the failure of the companies to be able to go through the process of a startup. For instance, not get a second round of funding. Some of these technologies are before their time.

What key lessons have you been learning from the Microgrid project?

In the beginning, Mac put in place a directive that any system I build, any device I buy must reduce the carbon footprint of Stone Edge Farm. The original goal was 50%. I did that the first year because we solarized everything. Then Mac said, “I want you to see how far below zero you can take it.”

People think of “microgrid” as a collection of wires, switches, control systems. We’re really working in a space of distributed energy generation. You do not have to build an $80 million project. Invest what you can every year, build your system the way you want it, and tune it to your needs.

There are different modes of operation for a microgrid. If the grid fails, you can enter “island mode” and you are self-sustaining. You have energy storage and generators. That could be a generator burning diesel or propane. Or it could be solar panels, wind turbines, batteries, fuel cells, hydrogen devices.

Then there’s the mode the distributed energy industry is struggling with, where your island has more energy capacity stored or in production than you can use internally. Hypothetically you could sell that to the utility.

What did you do at Stone Edge Farm?

We were going after being able to export electrons to the grid. We got a polite letter from our utility telling us that we could not have a connection agreement. We were a little broken-hearted because we have more capacity behind the meter than we could ever use. Parallel with the arrival of this letter, we had started to explore hydrogen.

Hydrogen stores instantly and is usable infinitely, which means you can put it in a bottle and use it today or you can use it a year from now. There is three times more revenue in the kilogram equivalent of the kilowatt. That’s why we talk about hydrogen-based microgrids — H-grids.

What is the business case for hydrogen-based microgrids?

This is California-centric for the moment. The legislature put into effect the Low Carbon Fuel Standard. For every kilogram of hydrogen we produce, we get a state credit for $2.17. This is one of the key vectors to changing the business model.

We turn on our electrolyzer, take that electricity, crack water, and make hydrogen. Once you’ve got hydrogen, you could use it through stationary fuel cells back into your own system. You could sell it to your neighbors in California as long as you don’t cross a road. Third, you could export it out of the side of a building to a truck. There are no bureaucratic entanglements when you look at H-grids. The state has actually stacked the deck in favor of hydrogen production.

Hydrogen is part of the Stone Edge Farm Microgrid. What happened during the wildfire last fall?

On October 8, 2017, I was awakened by a phone call from one of my assistant managers. He told me there was a wildland fire between Highway 29 and Sonoma. I called my son Troy, who lives next door to Stone Edge Farm. He said that power was still on, but it was very smoky and he could see active fire.

I told him I would contact Jorge Elizondo, who works with us and lived about three minutes from the farm, and that the two of them needed to put SEF into island mode. I had Troy shut down the hydrogen electrolysis system.

With no one on campus, our electrical usage dropped. Normally this would not be a problem because we would consume excess power with our hydrogen electrolyzer. But even with the smoke and ash in the air, our solar systems were producing more energy than we could consume. Troy and Jorge shut off some of the solar arrays as the battery system reached saturation charge.

The Microgrid operated for a total of 10 days in island mode. While this was a worry as it was happening, the fact that it worked should not have been a big surprise. A microgrid is designed to be able to operate on its own.

What’s next for the Stone Edge Farm Microgrid?

We have a lot of Enphase Energy inverters in our system. I explained to their technical officers what we observed during the fire with curtailing solar and asked if they could help us come up with a solution. Their smart inverter system will allow us to turn solar panels on and off one at a time, much like the volume on your radio. We are going to be beta testing that in the next few months.

We are adding a great deal of solar to our system. We are in a second review of installing a flywheel in the system. We are looking at a fourth hydrogen car. And we have broken ground on another microgrid called Silver Cloud. We’re not done by any means. Every time we explore something, we find something new.

The Environmental Leader Conference & Energy Manager Summit takes place May 15 – 17, 2018 at the Denver Marriott Tech Center. More information here.

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