Between June 6 and 10, the Department of Energy (DOE) held its Annual Merit Review (AMR) in Washington D.C. At the meeting, over 350 national lab activities were evaluated within the Vehicle and Fuel Cell Technologies Offices of the DOE. The array of projects was stunning -- from fuel cells, electrification, light weighting and more -- all aimed at reducing transportation emissions. In today’s SBFF, we provide a brief explanation of one DOE project presented at this week’s review, the Co-Optimization of Fuels and Engines (Co-Optima) project. Co-Optima aims to slash transportation emissions from internal combustion engines 30 percent by 2030.
The Transportation System Is Already Evolving
It’s safe to say that the future of the transportation sector will look nothing like today’s system. Indeed, companies like Uber and Lyft have already dramatically changed the way we get around in cities in just a few short years; self-driving cars are also throwing a potential wildcard into the system. But beyond who’s driving the car, what will the future fuels of transportation look like? Will we go electric, hybrid, fuel cell, biofuels, or a combination of these?
To make deep cuts to transportation emissions, a variety of strategies, including electric, fuel cells and robust public transportation will be needed. But how do we bridge the gap from today’s inefficient cars and trucks to these ultra-clean technologies? According to the DOE, in the near-term, we must design fuels and engines together, to create highly efficient internal combustion engines that reduce tailpipe emissions and boost engine efficiency by 2030.
Creating More Efficient ICEs Necessary
While internal combustion engines are more efficient and cleaner than ever, the transportation sector is still responsible for 27 percent of greenhouse gas (GHG) emissions, with half of all transportation emissions coming from light-duty passenger vehicles. Globally, transportation is responsible for 14 percent of emissions, but these emissions are expected to rise significantly.
Thanks to Corporate Average Fuel Economy (CAFE) standards, fuel efficiency has increased greatly in vehicles. Increasing vehicle fuel efficiency is a cost-effective way to significantly lower the transportation sector’s emissions and reduce vehicle lifecycle cost without requiring major infrastructure adaptations. In addition, fuel efficiency standards can have beneficial health effects as they lower other forms of harmful emissions, such as air toxics and ultrafine particulates.
According to DOE, internal combustion engines (ICEs) that burn petroleum will be around for a few decades, either as primary sources of mobility, or as range extenders for electric vehicles. Yet, even today’s new, more efficient ICEs, are still very energy inefficient. Only about 15 percent of the energy in each gallon of fuel is used for powering the vehicle. Energy is lost at multiple points, during fuel combustion, losses due to idling, aerodynamics as well as energy drain from things like the air conditioning and power steering systems.
Recognizing the efficiency limitations of the current transportation fleet, DOE is investigating future fuel and engine design through Co-Optima, a collaborative effort between industry and DOE. Optima’s goal is to reduce per-vehicle petroleum consumption 30 percent by 2030 using a combination of improved vehicle technology and use of low-carbon biofuel blends. If achieved, this could reduce petroleum consumption by 4.5 billion barrels and save consumers up to $50 billion.
Begun in Fiscal Year 2016, Co-Optima brings together researchers from the DOE Vehicle Technologies Office, the Bioenergy Technologies Office, and the National Laboratories, as well as stakeholders from the automotive manufacturers, the petroleum and refining industry, biofuels producers, federal agencies, industry and trade organizations and consumer advocacy organizations to look at designing engines and fuels together for optimal performance.
Cleaner Fuels for More Efficient Engines
As automotive manufacturers work toward meeting higher miles per gallon (mpg) ratings under the Corporate Average Fuel Economy (CAFE) standards, they are using a combination of vehicle technologies to increase fuel efficiency, including downsized engines and turbocharging. However, these newer, smaller engines require higher volumes of octane for optimized performance.
Where will we get the additional octane? Currently, there are two forms of octane available – gasoline aromatics and ethanol. Gasoline aromatics, or the BTEX complex, are a toxic mixture of benzene, toluene, ethyl-benzene and xylene. Health research suggests that even very low-level exposure to the BTEX complex, from gasoline additives and other petroleum products, may contribute to negative developmental, reproductive and immunological responses, as well as cardio-pulmonary effects. Incomplete combustion of the BTEX complex forms ultra-fine particulates (UFP) and polycyclic aromatic hydrocarbons (PAHs), which carry their own adverse health impacts even at low levels.
Ethanol is a cleaner-burning alternative to petroleum-based octane boosters. Additionally, the toxicity of ethanol is low compared to the health effects of BTEX and its combustion products, such as ultrafine particulates (UFPs) and polycyclic aromatic hydrocarbons (PAHs). Co-optima recognizes that ethanol is an excellent octane provider for today’s newer, more efficient engines. With an octane rating of over 100, ethanol is a cost-effective octane provider, and is already blended into the gasoline supply. In the near term, ethanol is the best available bio-based octane booster available.
Looking forward to the design of even more efficient engines, Co-Optima is investigating additional properties of oxygenates that may be important to optimize fuels for future engines – such as viscosity, volatility, burn rate and more. According to presentations at this week’s AMR, there are some promising bio-based octane molecules beyond ethanol that are being investigated.
The Road to Cleaner Vehicles Rocky, But Necessary
Although it took 100 years to build a petroleum-based transportation system, the world simply doesn’t have time to wait for a more sustainable system. While we continue increasing the share of electric vehicles, biofuels will likely still play a role in optimizing engine efficiency and reducing emissions in both the light and heavy duty fleet.
But, there are also challenges in bringing new fuels and engines to market– including potential changes to refueling infrastructure, refining, building sustainable supply chains for additional biofuels volumes, and consumer acceptance. The potential payoffs are also great – reduction of petroleum consumption, creation of new U.S. technologies and diversity to agriculture, as well as providing an important piece of a national low-carbon transportation strategy.
DOE will release the presentation and reports as a result of the AMR later this year, and the Bioenergy Technologies Office will also be discussing their role in Co-Optima at the 2016 Bioenergy Conference this July. Look for additional reporting in SBFF on this issue.
For more information see:
Energy Losses in a Vehicle, Consumer Energy Center of California