What You Need To Know About Organics to Energy

Proposed improvements to Montpelier’s wastewater treatment plant will bring in new revenue, lower plant energy bills, and reduce landfill disposal costs thereby saving City taxpayers money and reducing the City’s carbon footprint.

On November 6th, Montpelier residents will have the opportunity to vote on a critical upgrade to the city’s waste water treatment facility (known as the Water Resource Recovery Facility, or WRRF). Over the past two years, City staff have worked closely with the selected contractor, Energy Systems Group (ESG), to design an upgrade to replace aging infrastructure while also increasing the facility’s capacity to treat high strength organic waste, and use that waste to produce energy in the form of biogas (primarily methane). This additional biogas can then be used to heat the digesters and buildings at the plant, reducing fossil fuel use. In addition, by charging tipping fees for the organic waste it receives, reducing energy bills, and lowering the amount of sludge trucked to the landfill, the City will be able to offset a significant portion of the project’s cost, and that means less cost to users in sewer fees.


Montpelier’s Water Resource Recovery Facility (WRRF) has been recognized nationally for its energy efficiency and environmental performance. Since the facility accounts for approximately 30% of the City’s total electrical usage, energy efficiency measures can have a significant impact on plant operations and the City’s overall budget. Built more than 50 years ago, the WRRF’s aging infrastructure needs work. As the City began planning for needed upgrades, it recognized an opportunity to significantly increase the amount of biogas produced by the WRRF by upgrading its anaerobic digesters and bringing in additional high-strength organic waste from local food processors and haulers. This project is designed to create additional capacity in the plant’s anaerobic digesters and will use the biogas produced as fuel for onsite energy production. The goal is to offset the anaerobic digestion system upgrades through increased tipping fees and reduced energy and disposal costs with the potential to make the plant a “net zero” facility.

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How much will it cost?

The cost of the “Organics to Energy” project is $16.75 million (Phase 1) and is scheduled to start in spring 2019. Compared to just replacing the aging infrastructure (estimated at $13 million over the next 10 years), the Organics to Energy project will save over $250,000 in annual average energy, water, and sludge disposal costs. Phase 2 of the project (anticipated in 2020) will include the conversion of biogas to usable forms of renewable energy. Conversion alternatives the City will evaluate include: (1) cogeneration (producing electricity and heat); (2) heat for sludge drying and volume reduction; and (3) producing Renewable Natural Gas for sale to a third party.

  • Better value for the ratepayer and lower out-of-pocket costs

  • Plant can increase tipping fees & generate additional revenue to offset the cost of upgrades

  • Plant improves efficiency ($ of operating cost)/unit of treated waste

Water Quality Benefits

The Organics to Energy project will process and remove phosphorus from high strength wastes which would otherwise be either directly land applied or placed into commercial digesters whose digestate is land applied as fertilizer, contributing phosphorus to the ground water flowing into Lake Champlain and other waterways. The amount of phosphorus in treated water released by the facility will continue to meet all state standards for pollution control.

  • Additional phosphorus will be removed at the plant in the treatment process

A Move Towards Net Zero

Currently the WRRF has the highest heating load of all City departments

Currently the WRRF has the highest heating load of all City departments

Currently the WRRF accounts for approximately 30% of the City’s municipal energy use, from both electricity and heating oil (used to heat the digesters in the winter months). By increasing the production of biogas through improved anaerobic digestion, the WRRF will be able to heat its facilities with 100% biogas, eliminating fossil fuel use for heating (in FY16 the WRRF used over 13,000 gallons of heating oil!). In addition, Phase 2 of the project may include cogeneration to generate electricity, making it a net zero facility and bringing Montpelier significantly closer to reaching its Net Zero goal by 2030.

  • Plant improves energy efficiency per unit of treated waste

  • In both Phase1 & Phase 2 use of biogas produced at the plant will offset fossil fuel use for heating

  • Greenhouse gas emissions decline at Plant in both Phase1 & Phase 2 compared to present 

What is High Strength Organic Waste (HSOW) and where does it come from?

HSOW includes feedstocks in the form of dairy industry by-products, brewery and distillery waste, fats, oils and grease from restaurants and food products production, and de-icing agents from airports. Typically this type of waste is challenging to landfill or compost, and Montpelier can provide a much needed service by accepting these types of waste at the WRRF. In addition, the City receives “tipping fees” per gallon of waste, which have the potential to generate over $400,000 a year of additional revenue to the City.

Can the WRRF handle the increased amount of waste?

Yes. When the WRRF was originally built in the 1960s it was designed with the expectation that Montpelier’s population would continue to grow. Since then, population has actually decreased, so there is additional capacity at the plant to process additional wastewater. Currently the WRRF accepts leachate (liquid waste from landfills) and septage (sewage pumped from septic tanks) from the region, however due to space limitations at the receiving station the WRRF cannot take advantage of any additional capacity. The OE project will improve the receiving station to facilitate trucks entering and exiting.

For more information, visit https://www.energysystemsgroup.com/montpelier/

Kate StephensonComment