In 2019, the Dane County Department of Waste and Renewables constructed a $29 million renewable natural gas (RNG) processing facility, which uses cutting-edge technology to transform landfill biogas into renewable natural gas. Landfills are one of the leading sources of methane emissions—a potent natural gas that traps heat in our atmosphere. We can greatly reduce these harmful emissions by capturing methane before it’s emitted into the atmosphere and using it as a resource. Learn more about renewable natural gas and why it’s an important step to securing a more sustainable future in Dane County.
The Scoop On Landfill Gas
In a landfill environment, organic matter (like food and yard waste) breaks down in the absence of oxygen. This process of anaerobic decomposition produces something called landfill gas (or biogas).
When landfill gas escapes into the air, it releases methane, which is a big contributor to climate change. But when the methane can be captured and converted into a renewable energy resource, landfill gas represents an important opportunity to reduce emissions and to lessen our dependence on traditional fossil fuels.
Natural Gas vs Renewable Natural Gas: What’s the Difference?
Natural gas is traditionally collected by drilling deep through underground shale rock for oil. Extracting fossil fuel energy is intensive and it negatively impacts our environment. Renewable natural gas (RNG) is created when organic matter—anything that was once living—decomposes in the absence of oxygen. As organic materials decompose in a landfill, they emit a potent greenhouse gas called methane. By capturing and cleaning this gas, it can be transformed into RNG and used interchangeably with traditional natural gas. This creates a valuable source of clean fuel that comes directly from our waste stream. Renewable natural gas can also come from agricultural waste, wastewater, or even food and beverage waste.
Creating An Innovative Facility
One factor that makes Dane County’s RNG facility so innovative is its first of its kind offload station. The offload station located at Dane County’s RNG facility allows other bio-gas producers in the area, such as dairy farmers, to access the interstate pipeline and renewable energy markets. An interstate pipeline connect costs millions of dollars, an unreasonable endeavor for dairy farmers to pursue if they want to access broader energy markets. Dane County’s investment in this connection opens the doors for regional biogas producers to take advantage of these renewable energy markets at a much more affordable cost. This achievement increases the diversity, equity and inclusion in the types of stakeholders that can participate in the renewable energy market. Learn more about the RNG Facility's Offload Services here.
Dane County Landfill Tour (In Person): Join us on one of our monthly tours to learn more about our facilities, including the RNG plant! Registration.
Offloading RNG at Our Facilities: Interested in using our RNG Offloading Station? Check out our RNG Offload webpage here under, "Our Services", to learn more!
04.13.2020 Dane County Landfill Marks Milestone
04.15.2020 RNG Offloading Station at Wisconsin Landfill Receives Biogas
04.13.2020 County Landfill Receives 1st Load of Digester Biogas
02.03.2020 Dane County Renewable Natural Gas Facility: Powering A Clean Energy Future
11.07.2019 Industry Awards Provide a Fascinating Snapshot of Biogas Development in America
08.19.2019 Dane County Turns Waste into Profit and Reduces Greenhouse Gas Emissions
04.26.2019 Dane County Begins Turning Gas from Landfill's Trash into Vehicle Fuel
02.27.2019 Kwik Trip to Sell RNG Rroduced at Wisconsin Landfill Gas Project
10.01.2018 Dane County Working to Become a National Leader in Renewable Energy
04.18.2018 Dane County, Wisconsin, to Construct Biogas Cleaning System
11.07.2017 Dane County Leads Switch to Selling Gas Made by Manure and Garbage
Why is it important to capture landfill gases?
Under the Environmental Protection Agency's (EPA) regulations, all modern landfills are required to capture and manage the gases produced by the breakdown of waste in landfills. These landfill biogases consist of over 50% methane gas, a potent greenhouse gas that is also highly flammable. If not captured, these gases have the potential to migrate off site and cause potential explosions, or escape into the atmosphere and contribute to the greenhouse gas effect.
Given the important responsibility to protect the health of the community and the environment from landfill biogas, we have been actively capturing its landfill biogas, and converting this waste by-product into a renewable energy source using innovative ways that also enhance opportunities for equity and inclusion in the waste & renewables field.
How does Dane County collect renewable natural gas (RNG) from the landfill?
Just as a straw sucks up liquid, special pipes built into the body of our Rodefeld landfill use vacuum pressure to extract landfill gas from deep within. Inside our state-of-the-art RNG processing facility, the captured landfill gas is then passed through an intricate series of steps to remove any impurities. As it is cleaned, the methane in the landfill gas becomes much more concentrated. The graphic below illustrates at what stages different contaminants are removed as the landfill gas travels through the RNG facility. By the time the gas reaches the end of the RNG processing facility, it has achieved an industry standard of 96-98% methane concentration. This gas is now considered renewable natural gas and it comparable to the natural gas that can be used to heat homes or compressed into vehicle fuel.
What happens after the landfill gas is converted into RNG?
The completed RNG is injected straight into the interstate pipeline, which runs right next to the Rodefeld landfill site in Dane County. This means the RNG produced from waste in our community can be sold to natural gas markets across the nation. The same RNG is also used right here in Dane County to power our fleet of service trucks and snow plows.
$29 dollars is a big investment. How is it paying off?
This investment has delivered enormous economic and environmental benefits already. Between 2019-2022, the RNG facility has generated renewable natural gas equivalent to 4,800,000 gallons of gasoline and over $4 million in net profit that goes back to Dane County’s general funds to support other County services. Regional biogas producers have contributed an additional 2,800,000 gallons of gasoline worth of RNG to the renewable energy market by using the offload station.
How was landfill gas managed in Dane County before the RNG plant was constructed in 2019?
At Dane County’s Department of Waste & Renewables (W&R), we have a long history of innovation and utilization of landfill bio-gas for energy and fuel production. We have been producing electricity with landfill bio-gas since 1995 and utilizing compressed bio-gas for onsite vehicle fuel for nearly a decade.
What caused the County to explore transforming landfill gas into RNG?
Like many others in the industry, Dane County’s Power Purchase Agreement (PPA) was sun-setting in 2019, leaving the contract up for renegotiation at substantially lower electricity rates. This would have resulted in the loss of over $1 million in revenue to the County general fund. This presented an opportunity for Dane County to reevaluate the economic feasibility of electrical production compared to RNG and fortunately for us, a high pressure interstate natural gas pipeline ran right under the site. With the increase in value of RNG due to the EPA’s Renewable Fuel Standards (RFS) program and the lower value of landfill gas derived electricity, the decision was made to pursue RNG production to inject into the interstate gas pipeline and, among many applications, use it for compressed vehicle fuel.
Prior to this decision, we had innovatively experimented with using landfill bio-gas for vehicle fuel. In 2010 the County saw an opportunity to diversify their landfill bio-gas utilization and installed a small scale compressed natural gas processing skid to divert approximately 50 standard cubic feet per minute (scfm) for vehicle fuel. At first the County’s fleet of CNG vehicles consisted of a few pickup trucks, but as the reduced maintenance and fuel costs, and environmental benefits were realized, the County continued to expand its fueling capacity and fleet of CNG vehicles. Today, this fleet consists of over 100 CNG vehicles including a third of the snow plow fleet. Our early work to utilize landfill bio-gas for vehicle fuel was recognized by the EPA as the Landfill Methane Outreach Program’s (LMOP) Project of the Year in 2011.
Special Projects & Materials Manager | Dane County Department of Waste & Renewables
rathsack.allison@countyofdane.com
(608) 514-2319
