From Waste to Wheels: How Biogas is Powering the Future of Trucking

Introduction

Biogas is a renewable energy source produced from organic materials like agricultural waste, manure, municipal waste, plant materials, sewage, and food waste. Through a process called anaerobic digestion, bacteria break down these materials and release a mixture of gases, including methane, carbon dioxide, and small amounts of other gases. This biogas can then be collected and used as an alternative fuel source.

The methane content of biogas makes it a promising fuel option, as methane is the primary component of natural gas. Biogas with 60% or more methane content can be refined into renewable natural gas (RNG). RNG has the same chemical properties as fossil natural gas and can be used in place of conventional natural gas. When biogas is purified to vehicle fuel standards with at least 90% methane, it is known as biomethane and can be used in natural gas vehicles.

Using biogas as a fuel for vehicles has several advantages. It reduces waste and diverts methane emissions from landfills and manure management systems. Biogas utilizes waste materials, does not compete with food crops like biofuels made from corn, and has low net greenhouse gas emissions. Utilizing this renewable fuel can contribute to a circular economy of waste management and low carbon transportation.

Biogas Truck Engines

Truck manufacturers have developed biogas engines by modifying existing diesel engines to run on a combination of biogas and diesel fuel. These dual-fuel engines provide an opportunity to utilize renewable biogas fuel while maintaining the power and efficiency of diesel. Truck driving schools in Mississauga providing biogas truck engine knowledge to a great extent. 

The most common approach is to use high-pressure direct diesel injection along with low-pressure port injection of biogas. This allows the engine to run primarily on biogas at low loads and switch to mostly diesel fuel at higher loads when more power is needed. The diesel fuel ignites the biogas-air mixture.

Modifications include hardened intake valves and valve seats to withstand the hot corrosive combustion of biogas. The compression ratio may be reduced to prevent engine knock. And engine control software is tuned to manage the diesel and biogas fuel mixtures.

Dual-fuel engines can typically substitute 50-90% diesel fuel with biogas, depending on the engine model and load conditions. This provides significant emissions reductions compared to conventional diesel trucks. However, diesel fuel is still required for ignition, high loads, and cold starts.

Major truck manufacturers including Volvo, Scania, MAN, and Mercedes now offer biogas dual-fuel engines in their heavy-duty trucks. With the right engines and fuel systems, biogas can serve as a renewable fuel to reduce the environmental impact of freight transportation.

Benefits of Biogas

Biogas offers several key benefits as an alternative fuel source for truck engines:

- Renewable and sustainable: Biogas is considered a renewable fuel because it is produced from organic waste materials such as manure, municipal waste, plant material, sewage, green waste, and food waste. These organic materials can be continually replenished, making biogas a sustainable fuel source.

- Reduces greenhouse gas emissions: Biogas is a clean burning fuel that produces significantly lower greenhouse gas emissions compared to conventional diesel when used in engines. The collection of waste materials to produce biogas also reduces methane emissions from landfills and manure management.

- Utilizes waste materials: Biogas production provides a useful purpose for organic waste materials that would otherwise be disposed of. Capturing the energy potential in these wastes is an efficient use of resources.

- Can be produced locally: Biogas production facilities can be built close to the source of organic waste materials, allowing for localized fuel generation. This reduces reliance on importing fuels.

- Provides energy security: Biogas can help diversify a country's energy mix and reduce dependence on fossil fuels. The ability to produce fuel locally from feedstocks that are continuously replenished can improve energy security.

- Can power a range of applications: In addition to powering truck engines, biogas can also be used for electricity generation, heating, and other applications. The versatility of biogas makes it attractive as an energy source.

Biogas Production

Biogas is produced through a process called anaerobic digestion, where organic material is broken down by microorganisms in an oxygen-free environment. The primary sources for biogas production are landfills, sewage plants, and animal manure:

- Landfills - Organic waste like food scraps, paper, and yard waste in landfills produce methane gas through natural anaerobic digestion. This gas can be captured via a network of pipes and wells drilled into the landfill. Landfill gas is one of the largest sources of biogas.

- Sewage Plants - The sludge accumulated during wastewater treatment also undergoes anaerobic digestion by microorganisms. The gas produced can be collected and purified into biogas. Sewage plants provide a consistent and reliable source of biogas.

- Animal Manure - Livestock manure is high in organic matter and breaks down to produce significant amounts of biogas. Cattle, swine, and poultry are major sources of manure for controlled anaerobic digestion at biogas plants. On dairy farms, the gas can be used for on-site electricity and heating.

Properly utilizing these organic waste streams through biogas production provides an efficient means of generating renewable energy and reducing greenhouse gas emissions from landfills and manure. The biogas can be upgraded into renewable natural gas and used to power cleaner transportation like biogas truck engines.

Biogas Upgrading

Biogas produced from anaerobic digestion is composed mainly of methane and carbon dioxide, with small amounts of water vapor, hydrogen sulfide, and other contaminants. Before biogas can be used as a vehicle fuel, it needs to be cleaned and upgraded to increase the methane content and energy density.

The main methods for upgrading biogas include:

- Pressure swing adsorption - Uses adsorption materials like activated carbon to selectively adsorb CO2 from the gas stream. The adsorbent materials are regenerated through pressure reduction. This allows continuous operation.

- Water scrubbing - Passing biogas through water absorbs CO2, leaving behind methane enriched gas. The CO2 saturated water can then be degassed to recover the CO2. This is a simple but energy intensive process.

- Membrane separation - Uses semipermeable polymer membranes that allow methane to pass through while blocking CO2. This produces high methane content gas without using chemicals. The membranes need to be replaced periodically.

- Cryogenic separation - Low temperature distillation to liquify CO2 which can then be separated from the methane gas. This requires high energy input for cooling but can achieve very high methane purity.

- Chemical absorption - Uses amine chemical solvents like monoethanolamine to absorb CO2 from biogas. The CO2 is then released from the solvent after heating. The solvent must be regenerated after CO2 saturation.

Upgrading biogas to over 90% methane content produces renewable natural gas (RNG) that can directly replace conventional natural gas for vehicles. The choice of upgrading technology depends on factors like plant size, capital cost, operating cost, and desired methane purity.

Major Companies Developing Biogas Truck Engines

Several major truck manufacturers have developed and commercialized biogas engines in recent years. This section highlights three of the leaders in biogas truck technology.

Scania

Scania, based in Sweden, was one of the first truck manufacturers to develop commercial biogas engines in the 1990s. Scania offers a complete range of biogas trucks, including their 13-liter OC13 gas engine optimized for compressed biogas (CBG). Scania biogas trucks are used for a variety of applications like waste collection, public transportation, and freight transportation across Europe and beyond.

Volvo

Volvo Trucks launched their biogas trucks in the early 2000s and offers multiple heavy-duty models equipped with biogas engines. Their 13-liter gas engine can run on either CBG or liquified biogas (LBG). Volvo has delivered over 1,000 biogas trucks worldwide, with a strong presence in Europe.

Cummins Westport

Cummins Westport is a joint venture between Cummins and Westport that develops natural gas engines for the trucking industry. Their ISX12 G and L9N engines can operate on conventional natural gas or biomethane. Cummins Westport engines are used by truck OEMs like Peterbilt, Kenworth, Freightliner, and others. Thousands of trucks with Cummins Westport engines are on the road globally.

The major truck makers have played an essential role in bringing biogas truck technology to the market. Their continued innovation promises expanded adoption of biogas vehicles for heavy transport duties.

Fueling Infrastructure

One of the biggest challenges for widespread adoption of biogas-powered trucks is building out the necessary fueling infrastructure. Biogas needs to be compressed and dispensed at fueling stations designed specifically for compressed natural gas (CNG).

While there are over 1,600 CNG stations in the U.S. today, only a small fraction dispense renewable natural gas. Expanding biogas fueling stations will require significant investment and coordination between fleet operators, gas suppliers, and station developers.

Some companies are leading the way in deploying more biogas fueling stations. For example, Clean Energy Fuels Corp has opened RNG fueling stations in cities like LA, San Diego, San Francisco, and Dallas-Fort Worth. They partner with fleet operators like UPS to build stations that can handle larger volumes of biogas fueling.

Moving forward, incentives and policies that support biogas infrastructure development will be key. There also needs to be more public-private partnerships between municipalities, station developers, and vehicle fleets. With the right investments and coordination, a robust biogas fueling network can be built out to meet the needs of the emerging biogas truck market.

Cost Analysis

Converting diesel trucks to run on biogas can require a significant upfront investment, but can pay off in the long run through fuel savings.

The cost to purchase a new biogas-powered truck is approximately 20-30% more than a comparable diesel truck. Retrofitting an existing diesel truck to run on biogas also incurs upfront expenses of $25,000-$35,000 for the extra fuel tanks, upgraded engine components, and conversion equipment.

However, biogas fuel can cost up to 50% less than diesel. With the average long-haul truck traveling over 100,000 miles per year and achieving 6-7 miles per gallon, the annual fuel savings of switching to biogas can be $15,000 or more per truck.

Most estimates find biogas trucks reach cost parity with diesel after 2-4 years of operation. This breakeven timeframe depends on factors like vehicle purchase price, cost of biogas versus diesel, and annual mileage. Fleet owners able to secure low biogas fuel prices through on-site production or long-term supply contracts can achieve payback even faster.

Over the 10+ year lifespan of a truck, biogas models usually save $50,000-100,000 in fuel costs compared to their diesel counterparts. These fuel savings offset the higher upfront vehicle expense, providing a net financial benefit over time.

Environmental Impact

The widespread use of biogas-powered trucks has significant potential to reduce greenhouse gas (GHG) emissions from the transportation sector.

When biogas is used as a fuel source, it can provide a closed-loop system for carbon emissions. This is because the methane emissions from decomposing organic waste are captured to produce the biogas fuel. The carbon is then released again when the biogas is combusted in the vehicle's engine. However, this balances out the natural carbon cycle. Fossil fuels introduce new carbon into the atmosphere that has been locked underground.

Studies have shown biogas fuel can reduce GHG emissions from heavy-duty vehicles by at least 80-90% compared to diesel. The level of reduction depends on the feedstock source of the biogas. Waste-based biogas sees greater reductions than crop-based biogas.

The carbon intensity of biogas is far below even the most efficient diesel engines. As more fleets transition to biogas-powered trucks, they can dramatically decrease the overall carbon footprint of the freight and logistics sector.

Some biogas advocates argue it could play a pivotal role in helping countries achieve net-zero emission targets. With further technological improvements and infrastructure buildout, biogas trucks have the potential to transform emissions from heavy transport.

Future Outlook

The future looks bright for biogas-powered truck engines. As the technology continues to improve, adoption rates are expected to increase significantly.

Several key innovations are driving improvements in biogas truck performance. Researchers are developing new methods to increase biogas production efficiency and yield. This will lower costs and improve the viability of biogas as a fuel source. Enhanced biogas purification techniques will also boost energy density and engine efficiency.

Engine manufacturers are making advancements as well. They are optimizing biogas truck engines for power, efficiency, and emissions reduction. New engine systems are being designed specifically for biogas rather than just retrofitting diesel engines. This will unlock the full potential of biogas as a transportation fuel.

Major trucking fleets and logistics companies are starting to add biogas trucks to their operations. As more data becomes available demonstrating the reliability and cost-competitiveness of these vehicles, adoption rates will accelerate. This will drive further infrastructure development like biogas fueling stations along major trucking routes and at logistics hubs.

Government incentives will also play an important role. Several states are starting to offer tax credits, grants, and subsidies to promote biogas truck adoption. Federal support is critical as well to level the playing field. As support programs expand, biogas trucks will become more accessible and affordable for fleets.

Overall, the market outlook for biogas-powered trucks is extremely promising. Continued technology improvements paired with growing adoption will help biogas emerge as a major renewable transportation fuel worldwide. This will provide tremendous environmental and economic benefits. The future is bright for green trucking fueled by biogas.