GM, Ford R&D execs stress importance of improved, advanced fuels for future engine efficiency gains, GHG goals
In separate presentations at the 2017 SAE High Efficiency IC Engine Symposium in Detroit, R&D executives from GM and Ford each stressed the importance of improved, advanced fuels—among other technology developments—for their future engine efficiency gains and for long-term CO2 emissions goals.
David Brooks, Director for General Motors Global Propulsion Systems R&D located in Pontiac, gave a more medium-term perspective, emphasizing a pragmatic approach toward reducing CO2 with an eye to 2025. Meeting regulatory targets while keeping vehicles affordable will require the synergistic integration of fuels and engine technologies, he noted.
According to Brooks, among the technologies GM is looking to in the gasoline engine area are:
Continued aggressive downsizing. Key enablers are advanced boost systems and increased knock tolerance—meaning more knock-resistant fuels.
Compression rations between 13 and 14 to maximize work extraction. Key enablers are active valve actuation and increased knock tolerance.
Higher levels of dilution to enable EGR lean combustion at low temperatures. An enabler is more reactive fuels.
Brooks ticked off the requirements for future fuels in his talk:
High knock resistance with high sensitivity.
Low variability across the marketplace.
Near zero sulfur (<10 ppm).
Good low temperature catalyst reactivity.
Low propensity to soot.
We don’t need new fuels, we need improved gasoline with high RON, high sensitivity and low variability.—David Brooks
Thomas McCarthy, Chief Engineer for Powertrain Research & Advanced Engineering at Ford, took a longer-range perspective, looking out to requirements for 2050.
McCarthy stressed the need to take a well-to-wheels perspective, especially on the glidepath to the 80% reduction in GHGs projected to be required by 2050.
In a 2016 paper published in MRS Energy & Sustainability: A Review Journal, Chris Gearhart from the National Renewable Energy Laboratory (NREL) noted that, given the GHG budget allowable in 2050 with the projected vehicle kilometers traveled (VKT) gives a wells-to-wheels (WTW) GHG emissions target of 48 g/km (77 g/mile).
By contrast, however, a 2017 Tesla Model S AWD 90D carries a WTW CO2e intensity (US average) of 190 g/mile. The 2017 Chevrolet Volt extended range electric vehicle has a US average GHG intensity of 200 g/mile; the new 2017 Hyundai Ioniq Hybrid (not plug-in) has a GHG CI of 184 g/mile. (Plug-in vehicle GHG CI vary based on the carbon intensity of the electricity produced in a given region. All WTW GHG figures from fueleconomy.gov.)
McCarthy presented the problem this gap poses in the following slides, taken from a presentation in 2016 at an American Petroleum Institute industry forum:
|Vehicle technology improvements will only address a portion of the required decrease in GHG intensity to meet projected 2050 goals. Click to enlarge.|
In addition to the benefits that can be obtained from synergies between fuel properties and engine technologies, McCarthy said, there is a need to explore low-carbon fuels. E-fuels and fuels derived from biomass could offer a big contribution from a WTW standpoint, he noted.
Additionally, McCarthy noted, while decreasing emissions from the light duty sector will be significantly enabled by increasing electrification, the same does not automatically hold true for freight and aviation. The CO2 emissions from those sectors will become more important as light duty vehicle emissions drop, McCarthy said, and low-carbon liquid hydrocarbon fuels offer a promising way to reduce WTW emissions in those sectors, for which electrification does not currently offer as large a benefit.
Chris Gearhar (2016) “Implications of sustainability for the United States light-duty transportation sector” MRS Energy & Sustainability: A Review Journal doi: 10.1557/mre.2016.8