Introduction to Renewable Fuels

Renewable fuels are fuels produced from renewable resources, such as biodiesels made from animal fats or vegetable oils and bioethanol made from sugarcane or corn. Hydrogen gas can be considered a renewable fuel depending on how it is produced.

Renewable fuels provide a sustainable alternative to traditional, non-renewable resources such as petroleum. Different renewable fuels can be produced from organic feedstocks, such as switch grass, depending on the production process. Hydrotreatment, gasification, and transesterification are different methods used to produce renewable fuels.

Research into renewable fuel production is valuable both from an economic and an environmental standpoint. Renewable fuels could diversify the fuel options for vehicles and may also reduce CO₂ and greenhouse gas emissions.

History of Renewable Fuels

Wood-burning fires are likely the first human use of renewable fuels. Humans used wood fires for over 1.5 million years before the discovery of electricity. The Industrial Revolution marked the beginning of the widespread utilization of non-renewable energy through the use of coal-powered steam engines. Though the first automobiles were designed to run on renewable biofuels, cheaper petroleum-based fuels quickly overtook the market.

In the 1970s, a widespread fuel shortage renewed interest in alternative fuel sources, including renewable fuels. In 2007, the Energy Independence and Security Act was created in part to increase the domestic production of renewable fuels.

Why Renewable Fuels Matter

According to the Hubbert peak theory, global petroleum sources are rapidly declining. Many of today’s industries depend on petroleum-based fuels. The production of these fuels releases methane, a potent greenhouse gas, to the atmosphere, adding to carbon dioxide emissions during fuel usage. Therefore, it is increasingly important to shift away from petroleum and toward renewable fuels.

Renewable fuels may also be produced from municipal waste. Methane from municipal waste sources can be converted into biogas and renewable natural gas, the latter of which can be used in existing natural gas pipelines.

Renewable fuels may have the largest impact on the transportation industry. While other renewable energy sources, such as wind and solar energy, are not practical for many types of transportation, renewable fuels are. Hydrogen fuel cell vehicles, airplanes powered by biomass-based sustainable aviation fuels, and biodiesel-powered buses are just a few examples of how sustainable fuels have already affected the transportation industry.

In the 1970s, a widespread fuel shortage renewed interest in alternative fuel sources, including renewable fuels. In 2007, the Energy Independence and Security Act was created in part to increase the domestic production of renewable fuels.

Benefits, Challenges, and Future Developments of Renewable Fuels

There are numerous benefits to using renewable fuels. Renewable fuels will help us achieve net-zero carbon emissions and reduce greenhouse gases. They can also be produced from a variety of feedstocks, including municipal waste, potentially reducing the amount of waste that enters landfills. Renewable fuels will also increase our nation’s energy security by allowing more domestic production of fuels. This will also create new jobs.

A major challenge with renewable fuels is the cost associated with their production. Unless there are increased incentives or larger markets, large-scale industrial production of renewable fuels is not economically profitable. Biorefineries can convert biomass and waste resources into value-added chemicals, but they must be cost-competitive compared to petroleum refineries in order to achieve industrial buy-in.

As research into renewable fuels advances, the efficiency of their production, utilization, and storage will increase and costs associated with them will decrease.

Renewable Fuel Research at PNNL

Several research areas at PNNL involves renewable fuels, including some research areas of the Institute for Integrated Catalysis, such as optimizing catalysts for renewable fuel production. Other renewable fuel related PNNL research ranges from renewable fuel production to energy storage, fuel utilization and safety.

PNNL boasts many excellent projects in area of hydrogen and fuel cell research, which are managed by the DOE’s Hydrogen and Fuel Cell Technologies Office.  This research supports the H2@Scale vision for wide-scale hydrogen production and use across the nation. PNNL provides leadership in H₂ production, infrastructure use and safety. Research projects range from leading the development of solid oxide electrolyzer cells that generate hydrogen and oxygen from water to testing and developing polymer materials for use in hydrogen applications. Several PNNL researchers are involved in the various hydrogen related consortia, such as the Hydrogen Materials Advanced Research Consortium, where they investigate new ways to store hydrogen for later use, and Hydrogen Materials Compatibility (H-MAT), which focuses on overcoming materials limitations.

In the area of bioenergy technologies, PNNL researchers find ways to convert biomass and waste to biofuels. This research generally falls within one of three categories: algal biofuels, aviation biofuels, and waste-to-energy products. PNNL partners with the Department of Energy’s Bioenergy Technologies Office (BETO) to conduct this research.

In the area of algal biofuel research, PNNL partners with BETO to investigate algae strains for their potential as biofuels. As part of this, PNNL leads the Development of Integrated Screening, Cultivar Optimization, and Verification Consortium—or DISCOVR to increase the amount of biomass that can be produced per pond surface area per day.

PNNL’s aviation biofuels research made commercial success through a partnership with LanzaTech. What initially began as developing samples of high-quality jet fuel from ethanol has now grown to a scaled-up production of over 4,000 gallons of fuel. In October 2018, a Virgin Atlantic 747 jet flew the first commercial flight, from Orlando to London, using this sustainable fuel.

The utilization of waste as fuel provides a solution to two different problems. At PNNL, researchers are working to convert wastewater sludge into biocrudes that can be refined using conventional petroleum processes. This is achieved by using high pressure and temperature in a process called hydrothermal liquefaction. This leaves less waste in landfill and provides fuels for other use.

The renewable fuel research at PNNL has potential impacts across the transportation sector and beyond.