The manure digester in the town of Vienna could have a new purpose, generating compressed natural gas instead of electricity, as its contract with Alliant Energy is due to expire next year.
The digester currently takes in manure from three surrounding farms and produces electricity by burning the methane gas resulting from the digestion process, then sells it to Alliant Energy.
But Clean Fuel Partners is anticipating a much lower revenue stream in any renewed contract with Alliant, prompting the company to look for other alternatives, said John Haeckel, Clean Fuel Partners CEO.
“Alliant has made it clear that they would continue purchasing power from us but only at the wholesale cost of the energy,” Haeckel said, adding the wholesale cost would be roughly one-third of what Alliant currently pays.
The rate was set up for 10 years to encourage a new environmentally friendly technology to produce energy, according to Annemarie Newman, Alliant Energy spokesperson. The rate was higher than what the company pays for other generation resources.
“As power company, we look at securing power at the most affordable rate we can,” Newman explained.
To make the digester more profitable, equipment can be installed to purify the biogas produced to the interstate pipeline system’s compressed natural gas standards. It would then be delivered to the Dane County biogas processing facility for sale.
Haeckel said an investor is considering the prospect. Installation of the equipment necessary – estimated between $3 million to $4 million – would take approximately a year, he added.
The transition could provide greater benefits for area farms seeking to store manure and the environment as a whole.
Haeckel said it would allow the facility to use all three digesters rather than just the two. Currently, one sits idle. When the facility was originally built, it was anticipated five farms would use the it, but two did not participate.
Currently, the facility is limited to the sale of 2 megawatts of electricity, he added, so using the third digester would entail flaring the gas at an additional expense. Without that limitation, producing renewable natural gas would allow the facility to fill the third tank and take in more manure.
More participation from farmers would also reduce the phosphorous load in the Lake Mendota watershed; the digester separates solids and removes phosphorous, and the remaining liquid fertilizer is returned to the farmers.
The digester now produces energy from mostly manure, but 10 percent is non-farm waste.
“We will stop that,” Haeckel said about the other waste brought in. “We will look to bring in more manure from the surrounding area.”
County biogas processing facility
The new biogas processing facility at the county’s landfill is about 90 days from completion, according to Josh Wescott, chief of staff for Dane County Executive Joe Parisi. Like Clean Fuel Partners, the county currently generates electricity from the landfill for another utility company, Madison Gas and Electric. With that contract also expiring, county officials had been looking for an alternative use, and found biogas production to be a much more viable market, Wescott said. Siting a drop-off point at the facility for digester operators would create a more stable market for them, as well, and possibly encourage the development of other digesters. The county also budgeted for a $200,000 study in 2018 to look into possible locations for future digesters to process manure into biogas.
“It’s good for the lakes, it’s good for the area – it’s a really exciting time,” Wescott said.
The county will have invested about $25 million in the facility, but county officials estimate just a two-and-a-half to three-year payback, Wescott said. It should allow digesters to operate with more profit, as well.
“It’s a fundamental shift in how we’ve been producing clean energy. This overall shift is going to be good for the landfill operations,” Wescott said. “We’re talking in millions of dollars a year in revenue.”
Also, compressed natural gas burns cleaner than fossil fuels, eliminating carbon emissions.
The county’s facility will be the first in the country capable of receiving CNG from off-site facilities for use and connect that renewable gas with CNG gas stations locally and across the nation, according to the county executive’s office.
As for Clean Fuel Partners, Haeckel discussed the proposed changes with town of Vienna officials during a recent conference call, according to the town’s newsletter. Town officials are reviewing any additional truck traffic that could result from the new operation and the current payment in lieu of taxes the digester facility provides to the town.
Haeckel said he is unsure what additional truck traffic will be created.
“That manure is moving over the roads anyway. Think of us, in effect, as a stop between a manure collection pit and either [the farmer’s] road or his fields,” he said.
However, trucks will transport the compressed natural gas to inject into the pipeline facility at the county’s landfill, he said.
“I started that conversation [with town of Vienna officials], but it’s by no means over,” Haeckel said.