Power from Waste: A Step Towards Net-Zero Carbon Emissions

Maryland facility turns sewage into renewable bus fuel

Montgomery County in Maryland has started converting sewage treatment waste into fuel for its public bus fleet. The county partnered with WSSC Water to build a facility that captures methane gas from human waste and turns it into renewable natural gas. This gas now powers Ride On buses across the county.

The project represents a practical example of waste-to-energy technology at scale. Instead of trucking biosolids to landfill or dumping them elsewhere, the facility processes material from six treatment plants. It produces fuel that meets commercial gas standards and generates fertiliser for farms.

For UK businesses watching international approaches to carbon reduction, this project shows how public infrastructure can create revenue from waste streams. The facility cost $271 million but generates over $4 million annually from gas sales and renewable energy credits. It also cuts disposal costs by reducing waste volume by half.

Montgomery County aims to eliminate carbon emissions by 2035. This facility forms part of a wider strategy that includes electric buses and renewable power generation. However, the immediate commercial benefit comes from turning an operational cost into a revenue source.

The technology relies on anaerobic digestion. Microorganisms break down organic matter in sealed tanks without oxygen, producing methane gas. This process is not new, but applying it at this scale for vehicle fuel is relatively uncommon in the United States. Few similar facilities operate in the region.

How the Piscataway facility processes wastewater biosolids

The Piscataway Bioenergy Facility sits in Accokeek, Maryland. WSSC Water serves Montgomery and Prince George’s counties, producing roughly 8,000 tons of biosolids each month from wastewater treatment. Previously, trucks hauled this material away for disposal. Now the facility processes it on site.

Construction began in spring 2019 after county councils approved the project in 2014. The design-build approach involved PC Construction, Stantec, and Hazen and Sawyer. The facility reached substantial completion in November 2024, though operations began earlier in June 2024 when workers filled the digestion silos with biosolids.

The process works in stages. First, biosolids arrive from six treatment plants across the WSSC network. These plants are Damascus, Seneca, Parkway, Western Branch, Piscataway, and one other facility. The biosolids enter sealed tanks where bacteria digest the organic material without oxygen.

This digestion produces methane gas. The facility captures this methane and upgrades it to renewable natural gas that meets Washington Gas utility standards. Workers then inject the gas into commercial pipelines. Montgomery County purchases this gas to fuel its Ride On bus fleet under a five-year agreement signed in June 2023.

The process also produces Class A biosolids. These are higher quality than standard biosolids because they contain fewer pathogens. Farms in Maryland and Virginia use this material as fertiliser. The volume of biosolids drops by approximately 50% during digestion, cutting the number of truck journeys needed for disposal.

In addition, the facility generates about 2 megawatts of renewable energy. Some of this power runs the facility itself. The rest reduces electricity purchases from the grid by 30%. Consequently, the operation is partly self-sufficient from an energy perspective.

County Executive Marc Elrich described the project as a win for residents, commuters, and the environment. WSSC Water Commission Vice Chair T. Eloise Foster noted that recovering resources from wastewater makes both environmental and financial sense.

Annual revenues and cost savings from the facility

The Piscataway facility generates multiple revenue streams. Montgomery County pays approximately $700,000 per year for the renewable natural gas. This gas replaces diesel or conventional natural gas that would otherwise fuel the bus fleet. Therefore, the county reduces its fossil fuel purchases.

Beyond direct fuel sales, the facility earns between $3.2 million and $3.4 million annually from renewable energy credits. These credits trade on environmental markets. Organisations buy them to offset their own emissions or meet regulatory targets. For WSSC Water ratepayers, these credits offset costs that would otherwise appear on bills.

Disposal costs also fall. Reducing biosolids volume by half means fewer lorry trips to move waste. Each journey costs money for fuel, driver wages, and vehicle maintenance. Cutting these journeys by half saves substantial sums over a year. Meanwhile, selling Class A biosolids to farms brings in additional revenue, though the figures for this income stream are not publicly detailed.

The facility also reduces operational costs at treatment plants. Lower demand for lime and chemicals used in traditional biosolids processing cuts spending. Grid electricity purchases drop by 30% because the facility generates its own power. These savings compound over time.

The Maryland Department of the Environment provided a $2.5 million grant in April 2023. This funding helped close the project’s financing gap. However, the bulk of the $271 million capital cost came from WSSC Water budgets and bonds. The payback period depends on sustained RNG prices and credit values, but current projections show positive returns within two decades.

For UK businesses, the key lesson is how waste processing can shift from cost centre to profit centre. The facility turns a disposal problem into three revenue streams: fuel sales, renewable energy credits, and fertiliser products. This model works because the county guaranteed a fuel buyer and markets exist for credits.

Environmental performance and emission reductions achieved

The facility cut WSSC Water’s greenhouse gas emissions by between 13% and 40%, based on data from late 2023. This range depends on how you calculate baseline emissions. The lower figure compares total organisational emissions, while the higher figure looks specifically at treatment plant emissions.

Methane is a potent greenhouse gas. When organic waste breaks down in landfills or open systems, methane escapes into the atmosphere. Capturing it in sealed digesters prevents this release. Burning methane as fuel still produces carbon dioxide, but the net effect is lower because you avoid methane’s higher warming potential.

The facility also reduces nutrient pollution. Biosolids contain nitrogen and phosphorus. When spread on land or dumped, these nutrients can wash into waterways. Chesapeake Bay suffers from nutrient overload, which causes algae blooms and dead zones. Processing biosolids more thoroughly reduces nutrient loads that reach the bay.

Truck traffic falls because waste volume drops by half. Fewer lorries on roads means less diesel burned and fewer particulate emissions in local communities. This benefit is harder to quantify but matters for air quality near treatment plants and disposal sites.

The renewable natural gas displaces fossil fuel that would otherwise power buses. Montgomery County operates over 400 buses in its Ride On fleet. Not all use RNG yet, but the facility can produce around 295,000 million British thermal units of biogas per year. This volume is enough to run a significant portion of the fleet.

Grid electricity reductions matter too. The facility generates roughly 2 megawatts of renewable power. Maryland’s electricity grid still relies partly on fossil fuels. Therefore, reducing grid purchases cuts indirect emissions from power generation.

The project supports Montgomery County’s goal to eliminate carbon emissions by 2035. This target is ambitious compared to most UK local authority pledges. However, the county has multiple initiatives running simultaneously, including electric bus purchases and building retrofits. The bioenergy facility is one part of a broader programme.

Critical facts about the Piscataway project

• The facility cost $271 million to design and build, with construction starting in spring 2019 and substantial completion in November 2024.
• Operations began in June 2024 when workers introduced microorganisms into the digestion silos, with renewable natural gas flowing to pipelines shortly after.
• The facility processes biosolids from six WSSC Water treatment plants, handling roughly 8,000 tons of material each month.
• Annual revenues total over $4 million, including approximately $700,000 from gas sales to Montgomery County and up to $3.4 million from renewable energy credits.
• Biosolids volume decreases by 50% through digestion, cutting disposal costs and producing Class A fertiliser for farms in Maryland and Virginia.
• Greenhouse gas emissions from WSSC Water operations fell by between 13% and 40%, with grid electricity purchases dropping by 30%.
• The facility generates about 2 megawatts of renewable energy and produces roughly 295,000 million British thermal units of biogas per year.
• Montgomery County signed a five-year agreement in June 2023 to purchase renewable natural gas for its Ride On bus fleet, with potential expansion to other county facilities.

Why this approach matters for UK organisations

UK water companies face similar challenges to WSSC Water. They produce large volumes of sewage sludge and must dispose of it safely. Most UK biosolids end up spread on farmland or incinerated. Some water companies operate anaerobic digestion plants, but few capture gas specifically for vehicle fuel.

The Piscataway model shows how to create value from waste. UK businesses looking at net zero strategies often focus on reducing emissions. However, this project demonstrates how to turn waste streams into revenue while cutting carbon. The commercial logic works because multiple income sources offset capital costs.

Procurement criteria increasingly include carbon reduction. Public sector contracts often require suppliers to demonstrate environmental performance. For UK SMEs bidding on local authority or NHS contracts, showing how you manage waste and energy can influence scoring. Similarly, supply chain buyers want to know how suppliers handle operational emissions.

The facility also illustrates risk management. Waste disposal costs rise over time as landfill capacity shrinks and regulations tighten. Creating alternative disposal routes reduces exposure to future price increases. For manufacturers or food processors producing organic waste, on-site digestion might cut long-term costs.

Renewable energy credits add another dimension. UK businesses can sell Renewable Energy Guarantees of Origin (REGOs) when they generate renewable power. The value fluctuates, but it creates a revenue stream from assets that would otherwise just cut costs. Montgomery County earns more from credits than from gas sales, showing how market mechanisms can make projects viable.

The technical approach is proven. Anaerobic digestion is not experimental. UK farms have used digesters for decades. Scaling it up for municipal waste requires capital and planning, but the engineering is well understood. For businesses considering on-site energy generation, digesters offer an alternative to solar or wind when you have consistent organic waste streams.

Montgomery County’s 2035 net zero target sets a pace that UK organisations should watch. Most UK businesses target 2050, following the national legal commitment. Some aim for 2040 or 2045. Montgomery County’s timeline is tighter, requiring faster deployment of solutions. Their willingness to invest $271 million in waste-to-energy shows the scale of commitment needed to meet aggressive targets.

The project also highlights infrastructure dependencies. The facility works because gas pipelines exist nearby and Washington Gas accepted the renewable natural gas. Similarly, the county operates a large bus fleet that can use the fuel. UK businesses considering similar projects need customers for their outputs. Without guaranteed buyers, revenue projections become speculative.

Partnership structures matter too. WSSC Water built the facility but Montgomery County agreed to buy the gas. This arrangement splits risk and ensures demand. UK organisations might explore similar models where one party handles infrastructure while another commits to purchasing outputs. Such agreements can unlock funding by demonstrating revenue certainty.

Where to find detailed technical and policy information

The Maryland Department of the Environment website provides information on state grants and environmental standards for biosolids processing. They funded part of this project and regulate similar facilities across Maryland. UK businesses can review their standards to understand regulatory requirements for waste-to-energy projects in American markets.

Montgomery County government publishes details about its climate action plan and 2035 net zero target. Their website includes progress reports and project updates. For UK organisations benchmarking against international local authorities, these documents show how American counties approach carbon reduction.

WSSC Water operates a public website with information about the Piscataway facility. They publish operational updates and technical specifications. Water companies and engineering firms can review their approach to anaerobic digestion at scale.

The American Biogas Council tracks waste-to-energy projects across the United States. Their database includes technical performance data and economic analysis. UK businesses exploring biogas opportunities can use this resource to compare project costs and revenues.

For UK-specific guidance, the Anaerobic Digestion and Bioresources Association offers technical resources and case studies. They work with businesses implementing digestion projects in Britain. Meanwhile, our net zero hub provides practical guidance on carbon reduction strategies for UK SMEs, including renewable energy options and waste management approaches that reduce emissions while controlling costs.