High Octane Fuels
[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
Study finds butanol-gasoline blends effective to control soot from CI engines under Low Temperature Combustion
January 31, 2014
|(Left) Thermal efficiency and (right) soot from different gasoline-butanol blends at different EGR rates. Yang et al. Click to enlarge.|
A study by a team at Tianjin University found that the addition of n-butanol to gasoline for use in a compression ignition engine (CI) under Low Temperature Combustion (LTC) conditions has a significant effect on soot reduction. The peak soot value of a 30% butanol blend (B30) was 85% lower than that of pure gasoline; the EGR rate that corresponds to the peak value of soot is also decreased with the higher n-butanol fraction. Their study is published in the journal Fuel.
Partially Premixed Combustion involving the injection of gasoline fuel into CI engines is being explored by other researchers as a means to reducing simultaneously NOxand soot emissions. High octane fuels such as gasoline are preferred for high-efficiency and clean combustion at high engine loads, the Tianjin researchers note.
Global Bioenergies to collaborate with Audi on development of drop-in bio-isooctane
January 21, 2014
Global Bioenergies (GBE), a leading developer of one-step fermentation processes for the direct and cost-efficient transformation of renewable resources into light olefins (earlier post), has signed a collaboration agreement with Audi on the development of bio-isooctane—a high-performance drop-in biofuel for gasoline engines—derived from bio-isobutene. In 2011, GBE had announced an agreement “with a major German car manufacturer” regarding an undisclosed application of GEB’s technology. (Earlier post.)
Under the agreement, GBE will supply Audi with isooctane derived from isobutene produced at its new pre-commercial pilot system at the Fraunhofer CBP in Leuna. (Earlier post.) During the two-year collaboration, this agreement also foresees the possibility for Audi to acquire shares of Global Bioenergies corresponding to less than 2% of its capital.
Oak Ridge Lab study finds E30 blend and EGR can deliver significant efficiency improvements in optimized SI engines
January 17, 2014
Researchers at Oak Ridge National Laboratory’s National Transportation Research Center (NTRC) report that an E30 (30% ethanol) mid-level ethanol blend shows promise as a means for significant improvement in vehicle efficiency in optimized spark-ignited (SI) engines. Results of the study by Derek Splitter and Jim Szybist suggest that it could be possible to implement a 40% downsize + downspeed configuration (1.2 L engine) into a representative midsize sedan using this combination of optimized engine and mid-level alcohol blend.
As an example, for a midsize sedan at a 65 mph (105 km/h) cruise, estimated fuel efficiency of 43.9 mpg (5.4 l/100 km) with engine-out CO2 of 102 g/km could be achieved with similar reserve power to a 2.0 L engine fueled with regular gasoline (38.6 mpg/6.1 l/100km, engine out CO2 of 135 g/km). The data suggest that, with midlevel alcohol–gasoline blends, engine and vehicle optimization can offset the reduced fuel energy content of alcohol–gasoline blends and likely reduce vehicle fuel consumption and tailpipe CO2 emissions.
Researchers explore ethanol-diesel dual-fuel combustion for reduction in engine-out emissions
November 14, 2013
|Effect of ethanol energy fraction and PFI position on CO, NOx, HC, and opacity emissions. Credit: ACS, Padala et al. Click to enlarge.|
Researchers at the University of New South Wales (Australia) have demonstrated the potential for ethanol use in diesel engines with dual-fuel combustion, in which ethanol is injected into the intake manifold and diesel is directly injected into the engine cylinder. A paper on their work is published in the ACS journal Energy & Fuels.
The goal of such an approach is effectively to address some of the drawbacks of conventional diesel combustion, such as higher in-cylinder soot formation associated with locally rich mixtures and high flame temperatures and engine-out emissions of NOx.
Omnitek selects DD 12.7L Series 60 and Cat C15 engine models for diesel-to-gas conversion project at Port of Seattle
November 04, 2013
Omnitek Engineering Corporation has selected the 12.7 L Detroit Diesel Series 60 and the Caterpillar C15 engine models for the beginning of the second phase of a Puget Sound Clean Air Agency pilot project, which includes the development of diesel-to-natural gas engine conversion kits for these engine models and obtaining Environmental Protection Agency (EPA) approval.
Omnitek’s diesel-to-natural gas engine conversion system was selected as the best technology under the competitive grant process for the agency’s “Piloting Engine Upgrade Technologies in the Freight Mobility Sector” project. (Earlier post.)
Advanced Biofuels USA introduces “E30 Capable” high-octane fuels concept in EPA Tier 3 comments
July 02, 2013
Biofuel advocacy group Advanced Biofuels introduced the concept of “E30 Capable” vehicles as part of its comments to the the US Environmental Protection Agency’s (EPA’s) recently proposed Tier 3 motor vehicle fuel and emission rulemaking. (Earlier post.)
As part of the Tier 3 requirements, EPA proposes allowing vehicle manufacturers to request approval for an alternative certification fuel—such as a high-octane 30% ethanol by volume (E30) blend—for vehicles they might design or optimize for use on such a fuel. (Earlier post.) Advanced Biofuels suggests that “E30 Capable” vehicles can serve a practical key to transitioning to higher percentage blends of affordable renewable transportation fuels. Elements of the proposal include:
New MOF could enable more efficient and cost-effective production of high octane gasoline
May 24, 2013
An international team of researchers has developed a new metal-organic framework (MOF) that might provide a significantly improved method for separating hexane isomers in gasoline according to their degree of branching. A paper on the work is published in the journal Science.
Created in the laboratory of Jeffrey Long, professor of chemistry at the University of California, Berkeley, the MOF features triangular channels that selectively trap only the lower-octane hexane isomers based on their shape, separating them easily from the higher-octane molecules in a way that could prove far less expensive than the industry’s current method for producing high-octane fuel. The Long laboratory and UC Berkeley have applied for a patent on the MOF Fe2(bdp)3. (BDP2– = 1,4-benzenedipyrazolate)
Researchers propose evaluating alt fuel efficiency based on energy rather than volume; impact of ethanol on vehicle efficiency and GHGs
May 17, 2013
|Relative changes in vehicle energy efficiency (VEE) (km/MJ) on ethanol/gasoline blends over those on gasoline for different blending levels. Credit: ACS, Yan et al. Click to enlarge.|
In a policy analysis in the ACS journal Environmental Science & Technology, researchers from the Universities of Cambridge, Exeter and Oxford argue that, due to the increased emphasis on alternative fuels with drastically differing energy densities, vehicle efficiency should be evaluated based on energy rather than volume.
With that as a premise, they go on to show that the efficiency of existing vehicles can be both positively and negatively affected by ethanol content, ranging from −15% to +24%. As a result, they conclude, uncertainties in the net greenhouse gas (GHG) effect of ethanol, particularly when used in a low-level blend with gasoline, are considerably larger than previously estimated. Standard deviations increase by >10% and >200% when used in high and low blends, respectively.
Ford / AVL study concludes mid-level ethanol blend attractive as a long-term future fuel for use in optimized engines in US
April 19, 2013
A study by a team from Ford Motor Company and AVL has concluded that a mid-level ethanol blend—greater than E20 but less than E40—appears to be attractive as a long-term future fuel for the US for use in engines optimized for the higher octane blend. The team presented a paper on their work at the 2013 SAE World Congress in Detroit. Ford engineers also presented two other papers evaluating the effects of low to mid-level ethanol blends in spark-ignited engines at the conference.
In the face of increased regulatory stringency (e.g., US CAFE, California LEV 3 and pending US Tier 3), the combustion engine community is gearing up for an intensified push to deliver higher efficiency engines with lower fuel consumption and emissions. One of the many emerging possible technology pathways to achieve those goals is the use of a future high-octane fuel in optimized, higher-compression-ratio engines. (Earlier post.) The study by the Ford / AVL team provides an overview of the effects of such a future ethanol-gasoline blend in such an engine.
US EPA proposing allowing high-octane, higher ethanol content fuels as part of Tier 3 regs; E30 as example
April 03, 2013
As part of the proposed Tier 3 rulemaking on vehicle emissions and gasoline sulfur content released last week (earlier post), the US Environmental Protection Agency (EPA) is proposing to allow vehicle manufacturers to request approval for an alternative certification fuel—such as a high-octane 30% ethanol by volume (E30) blend—for vehicles they might design or optimize for use on such a fuel.
Higher octane fuels can lead to higher compression ratios which in turn can lead to more efficient gasoline engines and reduced fuel consumption. With turbocharged gasoline engines, there is a double benefit: higher compression ratios and increased boost. (Earlier post.) Having approval for such a high octane certification fuel would, the EPA proposed in the Tier 3 Notice of Proposed Rulemaking:
Study explores impact of alcohol-gasoline blends with early inlet valve closing at low and moderate loads on EGR tolerance
March 20, 2013
A team from Brunel University, MAHLE Powertrain and University College London studied the combined effects of different inlet valve operating strategies on combustion, performance and emissions with different ethanol and 1-butanol blends with gasoline in a single-cylinder spark-ignition research engine equipped with a fully variable valvetrain. Their paper is published in the journal Fuel.
The focus was to better quantify the effects of alcohol content and Early Inlet Valve Closing (EIVC) operation on EGR tolerance under the lowest speed-load conditions typically encountered (e.g., engine idle) while also quantifying the changes in optimum valvetrain settings at moderate speeds and loads where the effects of varying EGR tolerance were less dominant.
SwRI launches HEDGE-III; high-efficiency gasoline engine consortium targets LEV III, best efficiency of 43%
March 08, 2013
|HEDGE-III will investigate solutions to the primary barriers to high efficiency in gasoline engines. Source: SwRI. Click to enlarge.|
Southwest Research Institute (SwRI) has launched its third cooperative research program aimed at developing a high-efficiency gasoline engine for the light-duty automotive and medium-duty engine markets. This four-year effort will expand on earlier efforts to improve gasoline engine technology for future emissions and fuel economy requirements. (Earlier post.)
The HEDGE-III (High-Efficiency Dilute Gasoline Engine) consortium incorporates new and more aggressive efficiency, performance and emissions goals that are in line with existing and potential future regulations and expectations.
UTS study details efficiency benefits of combining ethanol direct injection with gasoline port injection
February 25, 2013
|Variation of indicated thermal efficiency with increased EER at 3500 rpm and light load. Zhuang and Hong, 2013. Click to enlarge.|
A new study by researchers at the University of Technology, Sydney (Australia) is contributing more detail on the leveraging effect of combining ethanol direct injection with gasoline port injection (EDI + GPI) to reduce gasoline consumption in a spark ignition engine while retaining performance. (The EDI + GPI concept was proposed by MIT researchers in 2005. Earlier post.)
Existing methods of using ethanol fuel—e.g., in blends with gasoline or neat—do not make the best use of ethanol’s potentials in improving engine performance, they noted in a paper on their work in the journal Fuel. Ethanol possesses a higher octane number and latent heat of vaporization, which allow the use of higher compression ratios and consequently can lead to the increased thermal efficiency. Ethanol fuel’s higher combustion velocity could also help increase the combustion efficiency and minimize the energy loss.
SAE High Octane Fuels Symposium: Is a new high-octane fuel a pragmatic pathway for higher engine efficiency in the US? (part 2)
February 06, 2013
As highlighted at the 2013 SAE International High Octane Fuels Symposium (HOF) last week, high octane fuels—combined with optimized engines—are viable enablers to higher efficiency operation. When ethanol is used as the octane enhancer, there is an added benefit due to the latent heat of vaporization of that fuel. (Earlier post.)
As articulated by Dr. Jim Szybist from Oak Ridge National Laboratory (ORNL), one vision of a high-octane ethanol fuel infrastructure and distribution system could include a standardized high ethanol/high octane fuel with ethanol content probably in the E20-E50 range. Refiners would continue to produce two high volume products in the gasoline boiling range: the Exx BOB (Blendstock for Oxygenate Blending) would have a low octane requirement (e.g., RON ~85), and be inexpensive for refiners to produce. Gasoline or E10 BOB would be premium-grade fuel for total coverage of legacy fleet.
2013 SAE International High Octane Fuels Symposium: the potential for high octane fuels (Part 1)
January 31, 2013
The 2013 SAE International High Octane Fuels Symposium (HOFS) this week in Washington, DC, explored the pros and the cons of high octane fuels, with a particular focus on using ethanol as the source of the octane improvement.
The “obvious driver” for the consideration of a high octane fuel (HOF), said MIT Prof. Emeritus John Heywood, one of the speakers, is that higher octane fuels would lead to higher compression ratios which would lead to more efficient engines and reduced fuel consumption. With the spread of turbocharged gasoline engines, he added, there is a double benefit: higher compression ratios and increased boost.