Pig-powered microgrid in North Carolina may be the future of rural cooperative supply
The Butler pig farm includes a range of clean energy technologies, and the state's cooperatives see its grid integration efforts as a model that can be replicated.
According to the United Nations, by 2050, the world's food production will need to increase 70% to feed a steadily-growing population. That means more farming, and more energy demand to support it.
The International Renewable Energy Agency estimates almost a third of the world’s energy is used by the agri-food supply chain. And increasingly, many types of farms, from rice to livestock, are tapping new energy technologies to reduce their carbon footprint and maintain reliability —particularly in areas where the energy supply may be less reliable.
It's not unusual to see a farmer utilizing wind or solar to reduce their energy needs, and at times the energy production can be more valuable than crops. But a growing number of agricultural businesses are going further, embracing grid edge technologies whole hog, if you will. And the fuel mix is often tied to the farm's primary business.
"There are microgrids in the agricultural sector," Peter Asmus, associate director at Navigant, told Utility Dive. "Using agricultural waste, I think that is something we'll see more of. … It's definitely a segment within the market.”
In the United States, perhaps the best known agricultural microgrid is Stone Edge Farm in Sonoma, Calif. Along with Bordeaux-style wines, they also produce olives, eggs, herbs and almost a megawatt of energy to fuel operations. The farm's microgrid is extensive, essentially a laboratory for grid edge ideas: it utilizes a half-dozen storage technologies, and during the California wildfires was able to island itself for more than a week.
Colorado-based Husk Power Systems developed systems in India to generate electricity from gasified rice husks that are often discarded by farmers, to power local communities. On the island of Hawaii, the North Kohala Microgrid Project uses wind to power water pumping, a frequent need of farmers, for a range of local agricultural operations.
And just last week, in North Carolina, a microgrid was commissioned at the Butler Quality Pork and Renewable Energy Farm in Harnett County, and connected to the South River Electric Membership Corporation (SREMC). The system, which is member-owned and controlled, integrates renewable biogas from swine waste, solar generation and energy storage, and can power 28 nearby homes for up to four hours at peak demand.
Powered by pig poop
The Butler microgrid is unique in many ways: it was privately built by a conservation-minded local farmer, and then later connected to the cooperative's grid. It remains under control of the farm, though in a later phase of development it will be transferred to SREMC.
But while the Buler microgrid may be unique, leadership at North Carolina Electric Membership Corp. (NCEMC), the power supplier for most of the state's member cooperatives, sees this as an example of what could be possible. There are more than 2,500 farms in North Carolina where the same process could be used, said Mike Burnette, senior vice president of power supply and COO of NCEMC.
Farmers "are huge environmental stewards, doing everything they can to not only sustain the farm for future generations but also to look at how these technologies can help offset the need for carbon intensive generation or large central generation," Burnette told Utility Dive.
"Part of the value of a microgrid is improved resilience. But more of the value is having additional resources at the edge of the grid that can be used for the good of the portfolio."
EMC senior vice president of grid infrastructure and compliance
Three years ago, NCEMC was considering adding energy storage to its system, when it was approached by Butler Farms about integrating its swine waste digester and generator into the grid. It was the first time that a member’s existing energy resources were integrated into a microgrid developed by the state’s electric cooperatives.
Now, as the system has grown and is helping keep the grid reliable, "we're hoping to use it as a framework," said Lee Ragsdale, NCEMC senior vice president of grid infrastructure and compliance.
The system includes a 250 kW / 735 kWh battery that will help bring more renewable energy onto the system, 20 kW of solar, a 100 kW diesel generator, the 185 kW biogas generator and control technology to make it all work.
Integrating grid-edge technology
There is a growing interest in grid edge technologies in the agricultural sector, said Burnette, and the cooperatives see "integrating leading edge technology and distributed energy resources as a vital part of our forward looking plan." NCEMC wants "to work with our members to leverage those assets and investments that our agri-biz community has made in clean tech, waste management and nutrition management."
More broadly, said Ragsdale, there are thousands of farms that could be able to replicate these strategies. Particularly in North Carolina, poultry farms would also be a good candidate.
One downside to an agricultural microgrid tends to be the cost. If you only judge its value based on the cost of generation, then it doesn't pencil out. But there are additional factors favoring adoption of microgrids in the ag sector.
South River already has a very reliable distribution system. "Part of the value of a microgrid is improved resilience," said Ragsdale. "But more of the value is having additional resources at the edge of the grid that can be used for the good of the portfolio."
NCEMC has been working with North Carolina State University, discussing how to continue advocating for projects like these. The value proposition, said Burnette, goes well beyond the cost of the energy. A hog farm has to do something with its waste, and disposal has a cost.
"There's more to the story that is unfolding as more and more people and universities get involved trying to model what those costs are," said Burnette. "You have to look at it from a far broader and wider scope, including all the pieces of farm management."
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