Martin Public Schools may end up going further than its recent solar array to reduce its power bills.
After swearing in new members at the school board meeting Monday, Jan. 21, superintendent David Harnish said a “combined heat and power,” or CHP, system could be purchased that could eliminate the district’s need to purchase electricity.
“While the solar panels are a function of the grid, this would be a function of the school system,” Harnish said of the proposed project. “This really makes us independent.”
CHP is also known as cogeneration. Used in industry for years, the price has come down enough that it can be used of the scale of the school campus, Harnish explained.
The system would sit outside in the same way air conditioning units do. Fueled using the same natural gas as the school’s new, efficient boilers, it would generate electricity and better capture excess heat and work in tandem with the district’s boilers.
Harnish said he asked Verde Solutions, the same company that completed the district’s solar panel array last year, to come up with proposals to further reduce the district’s energy bills. This proposal was one of four and was both more practical and more affordable. For example, he said cutting ties with the electrical grid entirely, building more solar panels and then building the batteries to store all of that energy until the campus needed it would all be a multi-million-dollar project.
All told, the proposed CHP system costs more than $575,000, 20 percent of which is for contingency spending.
Trade-off
The district uses approximately 445,000 kilowatt hours of electricity each year currently. Martin’s solar panels are expected to feed the grid by an estimated 150,000 kilowatt hours annually, so the district gets credit for that much electricity.
The proposed new CHP system would actually produce nearly all of the district’s annual needs, generating approximately 430,000 kilowatt hours annually. Just as with household electric bills that spike in the summer, the system would need to be supplemented. That’s where the solar panels come in handy.
However, the panels will be providing far more than the district will be drawing from the grid. Current state law limits how much power the district can sell to the grid, a process referred to as net metering.
“Because of the current rules, we’d forgo net metering for the excessive energy we produce. It would just be a trade-off,” Harnish said, to reduce the electricity bill to zero. He said Verde engineers had said at least 50,000 kilowatt-hours from the solar panels would be uncredited.
How it works
By burning more efficiently, the CHP units would reduce consumption of natural gas, saving an estimated $23,000 annually. Because it captures more of the heat from that process, it eases how hard the boilers have to work, saving an estimated $13,000 in the first year. Because it generates electricity, that’s power the district doesn’t have to purchase—to the tune of an estimated $55,000 in the first year.
Harnish said the current annual electric bill is approximately $56,000. That is lower than it was before the district added the new gymnasium and auditorium wing.
The half-million-dollar price tag of the new system could be financed over eight to 12 years.
“We wanted to start out with something similar in price to what Phase 1 cost,” Harnish said, referring to the solar panels. “With that one, we paid $50,000 down and are set for 10 annual payments of $50,000, although actually we think we can pay it off after we get to five years.”
He said Verde claimed the CHP units have a listed 30-year working life but if properly maintained they will last more or less indefinitely. Because they will ease the load on the boilers, those should last longer too.
After about 13 years, Verde estimates the system will have saved more than the district paid for it.
Board vice president Vince Tuinstra asked what would happen if power went down in the area.
“These would still be producing,” Harnish said. “We could probably keep the doors open and run things here.”
Board president John Vandenberg proposed that board members discuss this at the board workshop this month.
Harnish said, “If we did this, we’d be the first school district in the United States to do this.”
He said he was also in talks with the Gun Lake Tribe to see if they would be interested in any partnerships with this project.
It would be some time before the system could even be implemented; Harnish said this was a proposal for the school board to consider.
“Had I understood it this well before the bond issue, we would have integrated it in—it makes that much sense,” Harnish said.
Contact Ryan Lewis at rmlewis@allegannews.com or (269) 673-5534.
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