PNNL

For a typical American household, transportation costs are second only to housing expenses. The collaborative research initiative called Co-Optima is exploring new options for fuels and engines that work more effectively together, with the goal of reducing fuel costs, while delivering higher performance and cleaner air.

With nationally recognized expertise in bio-based fuels, catalysis, and chemical processing, Pacific Northwest National Laboratory (PNNL) serves as one of four national laboratories on the Co-Optima leadership team. The U.S. Department of Energy published the FY2017 accomplishments in April.

A key focus area is determining which bio-based sources, called blendstocks, could be combined with conventional petroleum-based fuels for the best results. Gas stations already provide ethanol-blended fuels at the pump, but the nation needs more options to increase fuel diversification and provide greater flexibility for refiners and fuel producers. New combinations of fuels could deliver significantly improved performance in conventional, hybrid, and plug-in hybrid electric vehicles, from passenger cars to freight trucks.

The potential impact is enormous. Co-Optima researchers have estimated that improved fuel economy could result in $35 billion in annual fuel cost savings for Americans. Furthermore, producing blendstocks from domestic biomass resources has the potential to increase U.S. jobs, support rural economies, and keep energy dollars in America—which ultimately enhances U.S. energy security and resiliency.

New Ingredients, New Recipes

Thousands of blendstocks can be generated from bio-based sources, but only some of them have the properties needed for today’s and tomorrow’s engines. How do researchers find or create the best ones?

It’s like this. Let’s say you want to make a chocolate cake, but you can’t use any ingredients made from traditional chocolate, cocoa, or carob. Instead, you must find a bio-based chocolate substitute, or maybe even create one from scratch. You must process it to get the taste and texture you need, and then blend it with the other ingredients to create a new recipe. If successful, you end up with a chocolate cake that is even better than the original, gives bakers more options for ingredients, and costs less to make.

That science-based “alchemy” is what Co-Optima is exploring—but for vehicle fuels instead of chocolate cake. Researchers are identifying fuel properties and design parameters that could maximize engine performance, reduce emissions, and improve fuel efficiency.

Research Accomplishments

PNNL researchers contributed to the following accomplishments in FY17:

• Narrowing Down the Family Tree. To focus the search for blendstocks that can reduce particulates in emissions while maintaining high efficiency, researchers assessed the suitability of certain chemical families. They identified five functional groups and eight other possible groups with properties that make them promising blendstocks, such as low soot formation and good flow in cold conditions.
• Pinpointing Possible Production Processes. To identify blendstock candidates that can be produced by using a variety of biological or chemical processes, researchers developed a unique software tool called RetroSynth. Compared with traditional searchers of the chemistry literature, this tool decreases the time from days to minutes to identify the reaction pathways, enzymes, and genes that are required to produce the target fuels. PNNL provided input data for the tool, which was led by Sandia National Laboratories.
• Mixing It Up. To demonstrate that the blendstocks can be made with the desired properties, researchers created two mixtures—mixed ketones and an iso-olefin mixture—that are readily derived from biomass and have the right characteristics. Demonstrations like this help target the blendstocks that could be produced using sustainable and economic manufacturing methods.
• Getting Big Results from Tiny Samples. It’s challenging to analyze a blendstock sample for the desired fuel properties when you have only a tiny amount to work with. Researchers used nuclear magnetic resonance spectroscopy to reveal the chemical structures within samples as small as 50 microliters, then built a computer model that shows which of the chemical structures could provide the most favorable fuel characteristics. With this approach, researchers can predict the properties of a single blendstock and optimize the properties when combining blendstocks to make a target fuel.
• Ranking for the Real World. To rank the candidate blendstocks’ potential commercial value, researchers analyzed 24 of them for technology readiness, economic viability, and environmental performance. Rankings in 17 sub-categories such as blendability, market competition, and carbon efficiency identified further opportunities to increase viability of certain blendstocks. In addition to providing information for these rankings, PNNL conducted techno-economic analyses to estimate the cost of blendstock production as part of the integrated analysis led by Argonne National Laboratory.

The Road Ahead

Armed with the promising blendstocks identified in FY2017, the research team is moving ahead in 2018 to examine each one for its potential to meet requirements such as fuel economy targets, vehicle material compatibility, and consumer acceptance.

Co-Optima is gaining attention. The biofuels and engine manufacturing industries are using the results to help inform their choices about fuel chemistries and to understand the efficiency impacts of fuel properties. In March, National Renewable Energy Laboratory Program Manager John Farrell briefed the U.S. House Committee on Energy and Commerce about Co-Optima research results as the Committee considered rulemaking related to transportation fuels.

The Co-Optima initiative is a collection of research projects sponsored by the U. S. Department of Energy’s Office of Energy Efficiency & Renewable Energy. It includes nine national laboratories, 13 universities, and numerous industry and government stakeholders.