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Are Diesels Cleaner than Gasoline Engines?

The conventional tradeoff between spark-ignited gasoline engines and compression-ignition diesel engines is that diesels are significantly more efficient—on the order of 30%. One reason for this is that diesel fuel is more energy dense (by volume). And more energy density translates into better fuel economy. Despite the added efficiency benefit, diesels are also more expensive due to: Continue reading

Reducing Our Oil Dependence

We were honored to make the final three in the inaugural Emerging Innovation Award from Securing America’s Future Energy (SAFE), and even more pleased to be named first runner up. SAFE’s sole mission is to improve America’s energy security by combating oil dependence. The Emerging Innovation Award was created to recognize and inspire the emerging innovations that have the most potential to help achieve that goal. Continue reading

The Emissions Dilemma

The dilemma for China, India and other densely populated, developing countries was starkly illustrated as my plane landed in Beijing on November 5. The smog outside was so thick that it looked like dusk when there were still hours of daylight left. The regulators in China and India know what is required to dramatically reduce vehicle emissions. In fact, China has embarked upon the most rapid decrease in tailpipe emissions that any major country has attempted. But, that poses a dilemma. Continue reading

Fuel Economy: Why the U.S. Continues to Trail Europe

When it comes to fuel economy, the United States is behind. Some say, way behind. In Europe, for example, consumers have been buying fuel-efficient, diesel-powered vehicles for decades. While diesel sales are growing here— increasing by 26% from 2011—they are still far short of European sales. In fact, diesel cars account for nearly 55% of passenger vehicle sales in Europe. So, why the big difference? Continue reading

Not All Two-Stroke Engines Are Created Equal

Dr. Gerhard Regner, Vice President, Performance and Emissions, Achates Power, Inc.
Dr. Gerhard Regner
Vice President, P & E
Achates Power, Inc.
Suramya Naik, Chief Engineer and Business Development Manager, India, Achates Power
Suramya Naik
Chief Engineer
Achates Power, Inc.

Does a conventional two-stroke have the same efficiency advantages as the opposed-piston, two-stroke (OP2S) engine? If you answered “no”, you’re right. But, do you know why?

One reason is due to heat transfer. As we highlighted in an earlier post and technical paper, the favorable surface area-to-volume ratio of the OP2S contributes to the engine’s inherent thermal efficiency benefits. So too does the architecture itself, which uses a different scavenging method than other two strokes.

For example, loop scavenged two-stroke engines use a cylinder head with two intake and exhaust valves. Continue reading

Designing an Opposed-Piston Engine for Light-Duty Applications

Regulatory agencies and consumers are demanding a reduction in CO2 emissions—putting greater pressure on auto manufacturers to enhance overall vehicle efficiency. What some don’t realize, however, is that the opposed-piston, two-stroke (OP2S) engine can provide reduced fuel consumption and low emissions without added cost and complexity. In fact, Achates Power has already demonstrated a 21% cycle-average and 15% best-point advantage versus the leading medium-duty diesel engines. But, do these same efficiency benefits extend to light-duty applications? Continue reading

Why Faster Is Better

I recently attended the Emissions 2013 Conference at Eastern Michigan University in Ypsilanti. It was a pleasure to be there and a treat to listen to some great talks. I was also there to present our opposed-piston, two-stroke engine’s capability of a low emissions and rapid light-off strategy.
 
With more stringent emissions and fuel efficiency requirements—not to mention the increased customer demand for fuel economy—some of the technologies discussed at the conference need to come sooner rather than later, with careful thought as to the cost incurred to the end product. Continue reading

Thoughts from Emissions 2013

I was happy to be invited to speak at the Emissions 2013 conference this week. Not only did it give me a chance to visit Ann Arbor, where I received my undergraduate education, but I was able to hear from some of the leading experts on the topic of vehicle emissions mitigation.
 
In addition to papers on the reduction of conventional emissions—oxides of nitrogen (NOx), particulate matter (PM), unburned hydrocarbons (HC) and carbon monoxide (CO)—the conference featured several papers on vehicle carbon capture.
 
This illustrates a dilemma regulators face to achieve clean air. Mandates to reduce vehicle emissions often increase operating and capital costs. Continue reading

Evaluating Engine Innovation

I had the opportunity to speak at the Engine Expo in Stuttgart this week. I was struck, as I always am, by the number of unconventional engines being promoted by small companies. There were new engine concepts from the U .S., Germany, England and the Democratic Republic of Georgia.
 
While I admire the inventiveness and ambition of the entrepreneurs behind these new companies, I don’t envy their task. The great age of engine innovation, it seems to me, was in the early part of the last century, when talented and hard-working engineers used their mechanical intuition to try a wide variety of engine ideas. By the second half of the last century, engine designs coalesced around the basic four-stroke concept of today. Continue reading

Changing the Game

Several weeks ago, I participated in AVL’s SAE World Congress Technology Leadership Panel. The topic: advanced propulsion. The focus: what are the new and innovative “game-changing” technologies?
 
As an industry, we’re facing daunting challenges, including CAFE 2025 and Tier 3/LEV III emissions standards. After decades of significant development and investment, there have been dramatic improvements in vehicle emissions, performance, safety, durability, quality and reliability. Now we must deliver year-over-year fleet-wide fuel efficiency improvements through 2025 without sacrificing what we’ve already accomplished and while keeping our products affordable. As such, game changers are required. Continue reading