Green Car Congress

NYC Hybrid Buses Improve Fuel Economy 45% Over Diesel, 100% over CNG

The series-hybrid buses offer up to 45% better fuel economy than diesel, and 100% better than CNG.

Orion VII series-hybrid buses operated by New York City Transit (NYCT) on the city’s most severe duty cycles achieved up to 45% better fuel economy than diesel buses and 100% improvement compared to comparable natural gas buses on an energy-equivalent basis, according to the results of a study released by the National Renewable Energy Laboratory (NREL).

The evaluation is part of a series of evaluations of new propulsion systems in transit technologies performed by the lab. from the U.S. Department of Energy (DOE). NREL recently concluded an evaluation of the GM-Allison parallel hybrid buses in use in Seattle. (Earlier post.)

The Orion VII series-hybrid buses with the BAE HybriDrive combine a 5.9-liter, 260 hp (194 kW) Cummins ULSD (Ultra Low-Sulfur Diesel) engine with a 120 kW traction generator. The electric traction motor delivers 250 hp (186 kW) and 2,700 lb-ft (3,657 Nm) of low-end torque.

The hybrid fleet proved the most reliable in the study, with 7,000 miles between road calls, compared to 5,000 miles for natural gas and 4,000 miles for diesel. The hybrid propulsion system also performed better than the other propulsion systems, with 10,000 miles between calls, compared to 8,000 miles for CNG and 5,000 miles for diesel.

The evaluation compared Orion VII low floor buses at NYCT with CNG propulsion (Detroit Diesel Corporation Series 50G CNG) and hybrid propulsion (BAE Systems HybriDrive propulsion system) against conventional diesel buses.

The CNG buses’ average fuel economy was 25% lower than the diesel baseline buses—a typical difference in fuel economy for low-average-speed operation for the spark-ignited natural gas engines.

The hybrid buses’ average fuel economy was 45% higher than the diesel baseline buses (ranging from 32% to 52% better than the diesel baseline during the evaluation period). The diesel baseline buses for the hybrid bus evaluation have diesel engines without exhaust gas circulation (EGR). The addition of EGR for emissions control would tend to lower the diesel baseline fuel economy.

The reported results represent eight out of a planned 12-month evaluation of these two groups of buses. An additional evaluation of NYCT’s order of 200 Orion and BAE Systems hybrid buses will be reported separately.

The eight-month evaluation period does not include summer months, which could have reduced the hybrid bus fuel economy advantage from air conditioning loading and the ability to collect regenerative braking energy into the batteries. The summer-month fuel economy information will be provided in the final results report on this evaluation. The hybrid buses had an average fuel economy 100% higher than the CNG buses.

In October 2005, New York City transport services ordered 500 more Orion VII series-hybrid-electric buses from DaimlerChrysler Commercial Buses North America. New York City Transit ordered 216 units, and Metropolitan Transportation Authority (MTA Bus) 284. (Earlier post.)

The exploration of alternative fuel technologies for urban transit has been driven, up to now, by imperatives for emissions reductions.

EPA Emissions Requirements for Transit Buses
Model Years	CO g/bhp-hr	HC g/bhp-hr	NOx g/bhp-hr	PM g/bhp-hr
1990	15.5	1.3	6.0	0.60
1992–1992	15.5	1.3	5.0	0.25
1993	15.5	1.3	5.0	0.10
1994–1995	15.5	1.3	6.0	0.07
1996–1997	15.5	1.3	6.0	0.05
1998–2003	15.5	1.3	4.0	0.05
2004–2006	15.5	2.4 combined or 2.5 with a limit of 0.5 for NMHC		0.05
2007–2010	15.5	0.14 (NMHC)	0.2	0.01

Diesel hybrid bus propulsion systems offer improved fuel economy during a time of fuel economy penalties for emissions control.

An issue that requires resolution, however, is the EPA’s current lack of recognition of the emissions reduction from a hybrid bus. Under current regulations, the emissions profile of the bus—or other heavy-duty vehicle—is determined by evaluating the diesel as a stand-alone engine. In other words, from an EPA point of view, the emissions profile of a hybrid bus is the same as the emissions profile of a non-hybrid bus using the same engine.

The California Air Resources Board (CARB) has recognized the emissions savings offered by hybrids, and as granted hybrid bus propulsion systems a 25% blanket reduction in emissions that can be used in the state implementation plan for emissions reductions. Currently, EPA does not recognize this benefit.

Resources:

• New York City Transit Hybrid and CNG Transit Buses: Interim Evaluation Results

157 MPG Lightweight Diesel to Debut at Geneva

Loremo LS

Loremo AG, a German company, is introducing the Loremo LS, a 1.5 l/100km (157 mpg US) diesel passenger car, at the upcoming Geneva Motor Show. Loremo had presented the concept for such a 1.5 liter car at the Frankfurt show in 2001.

The Loremo LS ( Low Resistance Mobile Light and Simple) combines lightweight design (450 kg / 992 lb) with a two-cylinder 15 kW (20 hp) turbo-diesel engine to deliver speeds up to 160 km/h (100 mph).

The car is built around a 95kg (209 lb) steel chassis in a patented linear cell structure. Longitudinal supports extend at fender height along the length of the entire vehicle, increasing stability and ensuring that the linear cell structure remains practically undamaged in offset and side crash-tests.

The centrally mounted cross-support on which the roll bars are mounted stiffens the longitudinal beams and houses the engine. Non-load-bearing, self-supporting, thermoplastic body panels mold to the linear cell structure and help the Loremo to achieve its aerodynamic shape.

This material is light weight, weatherproof, scratch-resistant and economical. It also replaces conventional paint with a thin film in the color of the car, during the manufacturing process.

Unconventional entry.

Entry to the car is from the front and from the rear. There are no traditional side doors. The entire hood of the car including the windshield tips forwards, allowing for upright boarding to the interior. The opened front shows the trunk, which also provides additional 600 mm (24 in) of crumple zone. The vertically-opening tailgate provides the entry to the back seats.

The Loremo uses a specially-developed rear differential-link axle combing the advantages of longitudinal- and semi-trailing link axles. With maximum load, the axle is indifferent to toe and camber at full suspension compression. In curves, however, the wheel leans inwards to achieve better lateral traction.

The Loremo accelerates from 0 to 100 km/h (63 mph) in 20 seconds.

The company is planning a more powerful version, the Loremo GT, with a 37 kW (50 hp) 3-cylinder engine. The GT offers fuel consumption of 2.7 l/100km (88 mpg US).

Loremo AG was founded in 2000 by Gerhard Heilmaier, Stefan Ruetz and Uli Sommer.

Loremo Models
	Loremo LS	Loremo GT
Engine	2-cylinder turbodiesel	3-cylinder turbodiesel
Output	15 kW / 20 hp	36 kW / 50 hp
Max. speed	160 km/h (99 mph)	220 km/h (137 mph)
Acceleration	20 sec. (0-100km/h)	9 sec. (0-100km/h)
Transmission	5-gear manual transmission
Drive	midship/rear wheel drive
Fuel Consumption	1.5 l/100 km (157 mpg US)	2.7 l/100 km (87 mpg US)
Fuel range	1,300 km	800 km
Weight	450 kg	470 kg
Drag	Cw=0.20; Cw×A=0.22 m²
Dimensions	384cm x 136cm x 110cm (l x w x h)
Price	< €11,000	< €15.000

Sasol Invests $32M in GTL and CTL Research Reactor

Sasol, the South African energy company and leader in coal-to-liquids (CTL) and gas-to-liquids (GTL) production, is investing R200 million (US$32 million) in the construction of an innovative Fischer-Tropsch design reactor at its research and development facilities in Sasolburg, South Africa.

The reactor will support the engineering design of the next generation of Fischer-Tropsch reactors for Sasol’s gas-to-liquids (GTL) and coal-to-liquids (CTL) technologies. Both CTL and GTL are key drivers of Sasol’s global growth strategy.

The reactor, on which construction recently began, should be ready for commissioning by the end of October 2006, with the first test runs planned for the beginning of 2007.

In partnership with Qatar Petroleum, Sasol is about to commission the world’s first commercial-scale GTL facility in the world outside of South Africa at Ras Laffan in Qatar. The plant, called Oryx GTL, will produce 34,000 barrels per day of liquid fuels from natural gas: 24,000 bpd of diesel, 9,000 bpd of naphtha and 1,000 bpd of liquefied petroleum gas (LPG).

The Oryx GTL plant is based on the Sasol Slurry Phase Distillate (SPD) process, which is, in turn, based on the Sasol Slurry Phase Fischer-Tropsh process and catalyst, Haldor Topsøe’s Autothermal Reforming and ChevronTexaco’s Isocracking.

Sasol Slurry Phase Distillate (SPD) Process. Click to enlarge.

[The new] research design reactor will assist Sasol in achieving significantly higher productivity in terms of gas throughput and product conversion rates over current generation designs. It will also support our quest to continuously lower the capital cost of the GTL process and improve operational efficiency, while also allowing us to test some novel reactor configurations.

—Sasol CEO Pat Davies

The Fischer-Tropsch design reactor is slurry-phase based and will have a capacity of producing up to 500 barrels of product per day. The reactor test program will be supported by a team of dedicated engineers and scientists from within the existing research and development team.

Sasol is targeting global GTL output of 450,000 bpd (with partners) by 2014.

Johnson Matthey to Build Plant in Russia for Emissions-Control Catalysts

Johnson Matthey has signed a Memorandum of Understanding (MOU) with the First Deputy Governor of Russia’s Krasnoyarsk Region, and the General Director of the Krastsvetmet Metal Company to secure a brown field site as the first step in a multi-million pound investment to build an autocatalyst manufacturing plant in Russia.

Over the last five years Russia has emerged as a significant player in the global automotive industry, with many international original equipment manufacturers (OEMs) investing in local manufacturing facilities. Johnson Matthey plans to build a plant to manufacture emission control catalysts for a wide range of both diesel- and gasoline-powered vehicles for the local Russian market, which will see emissions legislation requiring the use of catalysts come into force this spring.

Russia, which has lagged far behind European emissions standards, last year approved (Russian Federal Government Decree 609 of October 12 2005) an accelerated implementation plan that would bring the country closer into alignment with international standards over nine years. The plan calls for the mandatory implementation of Euro-2 standards beginning in April of this year; Euro-3 in 2008; Euro-4 in 2010; and Euro-5 in 2014.

The chosen site is located within the secure perimeter of the Krastsvetmet site; however the new factory will be wholly owned and operated by Johnson Matthey. Under the terms of the MOU, the new facility will purchase precious metal salts from Krastsvetmet for use in the manufacture of autocatalysts.

The site has direct on-site access to the Trans Siberian Railway, which will provide daily logistical links to the rest of the Russian Federation. Johnson Matthey already has significant business links with Krastsvetmet and since 2002 has licensed them technologies for the production of precious metal gauzes for the chemical industry.

Since making the first catalysts to control vehicle pollution in 1974, Johnson Matthey has supplied 1 in 3 of all autocatalysts ever made. A global leader in catalytic systems for emissions control, Johnson Matthey ECT has 10 manufacturing sites and 6 technology centers around the world.

Does Ford Have a Better Idea About Sustainability?

Defining Sustainability: Part Three of Eight
[Ed. note: We’re publishing the Ford piece in two installments. This week’s piece provides background context.]

By Jack Rosebro

The cover of Ford’s Sustainability Report

Ford Motor Company is the automaker most closely associated with the acceleration of society’s acceptance of the private automobile. While most automakers cite a long, yet often tenuous commitment to sustainable practices, Ford is also among the few that can reach down into its roots and come up with numerous examples of initiatives that are strikingly similar to some of today’s efforts towards sustainability.

In 1925, Henry Ford, the company’s founder, told the New York Times that “the fuel of the future is going to come from fruit...or from apples, weeds, sawdust...there’s enough alcohol in one year’s yield of an acre of potatoes to drive the machinery necessary to cultivate the fields for a hundred years.” The world’s petroleum industry, of course, went in another direction.

Many of Ford’s early business efforts were directed at reducing costs and exploring ways to combine the transportation and agriculture industries, especially after farmers were stuck with surplus crops and falling prices during the Great Depression.

The Soybean Car. Henry Ford is standing to the right.

Henry Ford is widely quoted as having remarked that “if we want the farmer to be our customer, we must find a way to be his.” In 1941, Ford exhibited the “Soybean Car,” a lightweight plastic-bodied experimental vehicle, at the Dearborn Days community festival in Dearborn, Michigan, where Henry Ford’s company was (and is) headquartered.

The body of the car was reportedly composed of soybean, wheat, hemp, flax, and ramie fibers in a phenolic resin. Some Ford vehicles were upholstered in a 25% soybean fabric, and Henry Ford would often sport a suit made from soybean fiber at media events.

The 2003 Model U

As part of its centenary celebration in 2003, Ford Motor Company exhibited the Model U concept SUV, which revisited many of Henry Ford’s early concepts. Soy products were used in the production of grease, body panels, and seat foam for the vehicle, which was powered by a modular hybrid powertrain that included a supercharged, hydrogen-fueled 2.3-liter engine.

At the time, David Wagner, Model U’s technology project manager, pointed out that “some of these concepts won’t come to fruition for years to come, but this is an important first step.”

The Model U was designed with help from Bill McDonough, who, with chemist Michael Braungart, popularized the “cradle-to-cradle” concept in the book of the same name, published in 2002. The cradle-to-cradle concept opposes the prevailing and non-sustainable cradle-to-grave manufacturing which, the book argues, is marginally delayed by even the best recycling practices.

In a cradle-to-cradle product design, which is an example of nature-inspired design often referred to as biomimicry, materials never become waste, but are nutrients that can remain in the biological cycle by either feeding healthy soil or returning to the manufacturing processes instead of moving downstream.

River Rouge plant in its heyday.

Perhaps the most famous collaboration between Ford and McDonough is the well-known redesign of the River Rouge manufacturing plant. Once the largest and most technically advanced industrial complex in the world, it employed more than 100,000 workers at its peak in the mid-1930s.

Built on the banks of the Rouge River, the facility unloaded Upper Michigan iron ore and Pennsylvania coal directly from freighters. Glass, paint, and cement factories were part of the complex, which boasted over ninety miles of railroad tracks and turned raw materials into completed cars and trucks.

But by the 1980s, the River Rouge plant was outdated and inefficient. More importantly, it had completely polluted the River Rouge watershed. Despite a decade of cleanup efforts, the river was considered to be among the nation’s most polluted waterways. Often running brown or yellow, it had reportedly caught fire several times.

In 1999, Bill Ford Jr., who was serving as the chairman of Ford’s board of directors at the time (he is now also the company’s CEO), announced a plan to transform the River Rouge complex into “a model of sustainable manufacturing,” again with help from McDonough’s Charlottesville-based architectural and environmental firm William Mcdonough+Partners.

Drought-resistant living roof composed of sedum, growing on top of the Dearborn Truck Plant final assembly building, designed to offset GHG production and reduce building energy costs.

Writing in Resurgence magazine in 2002, McDonough stated that “if I can design a building that makes more energy than it needs to operate, then I’m designing a building like a tree.” McDonough’s plans largely concern landscape design that includes over 500,000 square feet of living roof cover which can hold up to several inches of rainwater, rather than creating runoff into the Rouge River watershed, as well as specialized plants that absorb contaminants in a process called phytoremediation.

Notable as these commitments may be, they do not help customers or investors discern exactly what Ford Motor Company means when the company refers to sustainability.

Next week: Ford, part II: Defining sustainability, and measuring up.

Resources:

• Henry Ford’s Soybean Car

• Ford 2004-2005 Sustainability Report

Smart Cars for ZAP on Their Way; DaimlerChrysler Leaning toward Direct Entry

G&K Auto Conversion is completing the conversion of several hundred Smart Cars at its facility in Santa Ana, California to be purchased and distributed by ZAP. In addition, G&K will be delivering eighty-five Smart Cars owned by ZAP within the week.

G&K is in agreement with ZAP to modify the DaimlerChrysler Smart Cars for US standards and ZAP expects to deliver cars to ZAP licensed dealers shortly. The two-seater city car uses a 60hp, 698-cc 3-cylinder, rear-mounted turbo engine.

ZAP, which announced the Americanized version of the Smart car in February 2005, built up a large order backlog, but has had some issues with fulfillment. (Earlier post.)

G&K has obtained all necessary EPA and DOT certifications for model year 2005 and 2006 Smart Cars to meet US forty-five State standards. Certification for the remaining five States—California, Maine, Massachusetts, New York and Vermont—is underway.

News reports from Florida and Colorado have announced two separate business ventures claiming to be importing Smart Cars. G&K owner George Gemayel, states that G&K is the only entity approved to import and modify Smart Cars for the US market. G&K does not have a distribution agreement with the Florida or Colorado businesses.

Separately, however, DaimlerChrysler CEO Dieter Zetsche told the German newspaper Handelsblatt that the company is leaning in favor of launching the Smart minicar brand in the United States.

It is now more likely that we will decide in favor of, rather than against the US. The last word is, however, not yet spoken.

Mazda Donates 10 Prototype Tribute Hybrids to Orange County Fire Authority

The Tribute Hybrid at introduction.

Mazda North American Operations (MNAO) has donated 10 prototype Tribute Hybrid Electric Vehicles to the Orange County (California) Fire Authority (OCFA). The Tribute Hybrid is based on the technology of the Ford Escape Hybrid. (Earlier post.)

The vehicles are the first of 30 total Tribute Hybrid SUVs that Mazda will loan to fire agencies across Southern California.

The Tribute Hybrid—which Mazda unveiled at the Tokyo Auto Show in 2005—uses a Mazda 2.3-liter engine modified to run on the Atkinson cycle for superior fuel efficiency. The engine delivers output of 99kW (133hp) at 6,000rpm and maximum torque of 167Nm at 4,250 rpm.

A 70kW electric motor provides all-electric operation at speeds up to 40 km/h (25 mph), and then provides power assist to the engine when extra torque is needed. During deceleration, it charges the 330V NiMH battery.

Relative to a gasoline-only Tribute with the same engine model, the Tribute Hybrid provides 32% better fuel economy during highway operation and 74% better fuel economy during urban operation. It can cover at least 400 miles (640km) on one tank of gasoline.

The hybrid meets California’s AT-PZEV emissions standards.

The Tribute HEVs are painted in the red and white color used by regional fire authority vehicles and will be in service for two years. They will mainly be used for educational programs and fire safety and prevention programs at local schools.

The Tribute Hybrids are not yet on sale.

Although we don’t sell a Tribute HEV now, the varied driving conditions these vehicles will be put through, as well as the input on on-road performance we will receive from the fire agencies, will be valuable in the development of our first production HEV.

—Jim O’Sullivan, MNAO’s president and CEO

The Emissions and Energy Outlook for Medium- and Heavy-Duty Vehicles

Medium- and heavy-duty vehicles represent the second-largest consumer of energy in the US transportation sector, behind light-duty vehicles but ahead of every other transportation mode, according to the Energy Information Administration.

By 2030, the transportation sector’s total annual energy consumption will increase 46.5% to an estimated 39,729.9 trillion BTU (40 quads), equivalent to 7.1 billion barrels of crude oil per year, according to EIA’s long-term forecast in the Annual Energy Outlook 2006. (Earlier post.)

During that time, the share of total energy consumption of medium- and heavy-duty trucks will increase by about two percentage points—from about 17% to 19%. In contrast, the share represented by light duty vehicles will decrease by a percentage point from about 59% to 58%.

This makes trucks of particular interest for energy and emissions controls.

For the past 30 years, research and development in heavy-duty vehicles focused primarily on emissions reductions. Successful implementation of the impending 2007/2010 emissions regulations will result in extremely clean heavy-duty diesel systems, with reductions in certain emissions of about 100-fold from the 1960s, when concern about tailpipe pollutants first started to be taken seriously.

The outlook for these systems was the topic of a two-day conference organized by WestStart, the US Army National Automotive Center and the Federal Transit Agency. The general sense of the 6th Annual Clean Heavy-Duty Vehicle Conference was guardedly optimistic.

Engine makers are rolling out their 2007 diesel engine solutions, and are beginning to lock down their design and development plans for their 2010 engines. There was even a sense among a few of the speakers that the industry might be “done” with the emissions issue, and could focus on the two other strategic areas that were emphasized throughout the conference as the necessary next campaign: energy consumption and CO₂ emissions.

We are just at the starting point with respect to energy consumption and CO₂ emissions...I’m optimistic.

—Michael Walsh, international transportation consultant

Not surprisingly, the energy consumption issue is tied, longer term, to maintaining the emissions reductions currently being put in place. Under a business-as-usual scenario, energy consumption continues to grow rapidly, with the sheer number of vehicle miles travelled overtakes the reductions achieved through the 2007/2010 technologies with aggregate increases in NO_x and PM.

As a result, numerous speakers, in presentation after presentation peppered with concern over oil supply (and peaking), fuel prices and climate change, emphasized the need for more efficient heavy-duty vehicle systems, including diesel engines with optimized combustion, hybrids of various forms (hydraulic hybrids are gaining significant momentum) and alternative fuels (gaseous and synthetic).

But while the long view is important, there are still numerous issues to be resolved with actually delivering on the 2010 solutions, with the clock ticking down. These issues range from the cost of the new systems—some estimates pegged the cost of a 2010 diesel engine at twice that of a 2004 diesel—and the concomitant need for other technology approaches that might not be so costly, to driver training, and even to reconfiguring pipeline delivery to prevent sulfur contamination of Ultra Low-Sulfur Diesel.

The industry may be “done” with emissions in theory, but not in the details of operational implementation or deployment.

Background: 2007/2010. In 2001, the EPA finalized a set of regulations for future diesel fuel and heavy duty diesel on-road exhaust emissions. The fuel regulation specified the transition to 15ppm (at the rack) Ultra Low-Sulfur Diesel that is currently underway and will be in place by the end of the year.

Emissions standards were set for 2004 at 2.5g/bhp-hr NO_x+NMHC and 0.10g/bhp-hr PM. The 2010 target is 0.2g/bhp-hr for NO_x and 0.01g/bhp-hr PM—an order of magnitude reduction for both.

The PM emission standard takes full effect in the 2007 heavy-duty engine model year. The NO_x and 0.14g/bhp-hr NMHC standards will be phased in for diesel engines between 2007 and 2010 based on percent-of-sales: 50% from 2007 to 2009 and 100% in 2010.

Most engine manufacturers will likely use the NO_x phase-in provisions along with averaging to certify engines to a NO_x value roughly halfway between 2.5g/bhp-hr NOx+NMHC and the 0.2g/bhp-hr NO_x levels through 2009—i.e., approximately 1.2g/bhp-hr NO_x.

The basic 2007/2010 approach. The basic approach to meeting the 2007 emissions standards in the US is to try to reduce engine-out emissions with a number of approaches, including higher-pressure (2,000 bar) injection and improved boosting; to use Exhaust Gas Recirculation (EGR) for NO_x reduction; to add a catalyzed diesel particulate filter with active regeneration to the system for the PM; all coupled with the use of ULSD.

The ULSD is critical to keeping the catalyzed diesel particulate filter’s operations—sulfur in the fuel can poison the catalyst. Furthermore, given the use of EGR, sulfur in the fuel can results in recirculated sulfuric acid in the exhaust, to the detriment of the engine internals.

The 2010 approach will see additional efforts on the combustion side, likely through the advent of some partial HCCI regimes; higher injection pressures (2,500 bar); more improvements on boosting; the use of variable valve actuation; and the addition of urea SCR for NO_x reduction.

With the aftertreatment that we have, the user has to become more involved when he specifies our truck...Aftertreatment requires a systems approach. It is not an add-on. It has to be considered from the beginning.

—Alan Karkkainen, Director, Future Technologies, Engine Engineering, International Truck and Engine

Alternatives. While diesel is clearly the default approach for many—especially for the long-haul highway applications—other options exist. Compressed natural gas, or hydrogen-compressed natural gas blends (HCNG) delivers an emissions—and perhaps price—benefit. Clean-burning synthetics such as GTL are another option, although given limitations on production, that would likely be in the form of blends.

Other engine approaches are possible, however. Dr. Nigel Gale from Southwest Research Institute gave a presentation on HEDGE—High Efficiency Dilute Gasoline Engine—a consortium-based approach to enabling gasoline engines to meet the performance, durability, and emissions requirements of heavy duty vehicles. (Earlier post.)

The HEDGE consortium, led by SwRI, is exploring the use of high-energy ignition coupled with more sophisticated injection and control to meet 2010 emissions requirements while meeting the power needs of the heavy-duty market.

Should it prove out, one of the benefits would be the cost. While SwRI sees the cost of diesel engines rising from $33/kW for a 2002 engine to $70/kW for a 2010 engine, the cost of a 2010 HEDGE engine would be around $37 or $38/kW. (More on HEDGE in a subsequent post.)

Energy Consumption. The average fuel consumption for heavy-duty vehicles in 2005 was approximately 5.6 mpg of gasoline equivalent for all fuels, according to the EIA. The agency sees a very slow improvement in that figure to 6.43 mpgge by 2030.

By contrast, the DOE’s More Electric Truck research program set a fuel economy target for tractor-trailer combinations of 10 mpg. The approach the DOE is encouraging is to focus on aerodynamic resistance, combustion efficiencies, reduction of parasitic loss and the reduction of idling though electrification of systems and the use of fuel-cell APUs, and thermoelectric waste heat recovery.

Improvements in fuel economy are of immediate interest to any business. The countervailing force to that urge for improvement, however, is concern over the capital cost of new equipment and an aversion to the embrace of what might prove to be risky technologies.

The market works very very well for heavy-duty trucks...market forces are aligned for improving fuel economy over time.

—Drew Kodjak, Executive Director International Council on Clean Transportation

Hybrids. Hybrids are emerging as an important factor for certain commercial—and military—applications. Just a few days before the conference, UPS announced that it was ordering 50 hybrid package delivery vans from International.

These hybrids are derived from work done by Eaton/International and Ricardo under the DOE’s Advanced Heavy Hybrid Propulsion System (AH²PS), and use a similar hybrid-electric powertrain to the one being deployed in the Hybrid Utility Truck also under development by International. (Earlier post.)

While businesses might in theory be more disposed in higher percentages to a more immediate adoption of hybrid technology than consumers (the fuel cost factor), there are a number of barriers to hybrid commercialization, according to a panel of speakers on the topic at the conference.

The barriers include:

• The high cost of components;
• The need for approved testing standards for fuel economy and emissions;
• Insufficient in-use data;
• Business case still developing (the price of fuel is not predictable);
• Rate of acceptance of new technology by customers versus the cost to manufacturers to enter a new market;
• Component supplier infrastructure and capacity; and
• Technician training

Although transit buses are a visible application for hybrids, and although the speakers from Seattle and Orange County Transit who spoke on their experiences with the hybrids were “pleased as punch,” the transit market—with 2,000 to 4,000 total new buses per year— is too small to make a significant impact on commercialization. Commercial hybrids need to rely on trucking for a substantive market.

Hydraulic hybrids are gaining significant interest for commercial application—a surprise to those who might have dismissed it as a curiosity a few years ago.

We are extremely pleased with the hydraulic technology. We believe there will be significant demand for this technology...we believe we will have hydraulic hybrids in the low 1,000s by 2010.

—Merrilyn Zaw-Mon, Director of Compliance and Innovative Strategies Division, US EPA

Eaton is targeting 20-30 vehicles this year with its Hybrid Launch Assist technology (earlier post). The company is committed to commercializing its HLA hybrids with 18–24 months. The “end game” for hydraulic hybrids, however, is a series-hybrid configuration.

In that configuration—which is what the EPA is working on in conjunction with its partners for UPS (earlier post), the engine powers a hydraulic pump rather than a motor.

Margo Oge, Director of EPA’s Office of Transportation and Air Quality, believes that the series hybrid will deliver a 70% reduction in fuel consumption in certain urban applications.

Separately, Dana and Permo-Drive are working on a hydraulic hybrid application for the military. (Earlier post.)

In the commercial market, everything is application-specific, requiring different technologies. There is no one solution that works in a commercial application because you have these application-specific requirements.

—Ed Greif, VP Intelligent Hydraulic Drive Products, Dana

Mercedes-Benz Premiers New Gasoline Direct Injection System for More Power and Lower Fuel Consumption

The direct-injection engine with aftertreatment system. Click to enlarge.

Mercedes-Benz has introduced the world’s first gasoline engine with piezoelectric direct injection and spray-guided combustion—the Stratified-Charged Gasoline Injection (CGI) engine. The spray-guided direct injection system first appeared in a mild-hybrid concept car Mercedes-Benz showed at the Frankfurt show in 2005. (Earlier post.)

The new 215 kW (292 hp) 3.5-liter six-cylinder engine will enter the market in the second half of 2006 in the CLS-Class as the CLS 350 CGI. In the European combined driving cycle, the gasoline direct injection system improves fuel consumption by 10% over the counterpart V6 gasoline engine with port injection and fully variable valve timing.

Estimated fuel consumption for the CLS 350 CGI is 9.1 liters/100km, or 26 mpg US.

In a wall-guided system, the stream of fuel hits the piston floor, forming a cloud of fuel and air that moves toward the spark plug (top). In spray-guided gasoline direct injection, a hollow cone of fuel forms at the injection nozzle. This cloud of fuel and air remains stable up until the precise moment when it needs to ignite (bottom).

The spray-guided injection achieves better fuel efficiency, and thus also higher thermodynamic efficiency, than conventional wall-guided direct injection systems. The new system will form the basis for future engine development work in this output class.

The main advantage of the CGI engine is in the stratified operating mode from which it takes its name. During this mode the engine is run with high excess air and thus excellent fuel efficiency.

Multiple injection extends this lean-burn operating mode to higher rpm and load ranges too. During each compression stroke, a series of injections takes place, spaced just fractions of a second apart. This improves mixture formation, combustion and fuel consumption.

While stratified charge operation was previously only possible in the low part-load range, the new Mercedes direct-injection engine can still operate in this lean-burn stratified mode at speeds in excess of 120 km/h (75 mph). Above this, the engine switches to homogeneous operation where the fuel/air ratio is 1:14.6 (lambda = 1).

When driving on main roads and highways at largely constant speed and with proper anticipation, the CGI engine outperforms the fuel economy of the six-cylinder engine with conventional injection technology by up to 1.5 liters per 100 km, a saving of up to 15%.

The engine also delivers 15 kW (20 hp) more power than the conventional-injection V6 and 4% more torque (365 Nm).

The CGI injection system. Click to enlarge.

Injection system. The fast-acting, high-precision piezoelectric injectors are the critical enablers to the system. The piezoelectric valves have injectors which open outwards to create an annular gap just a few microns wide. This gap shapes the fuel jet and produces a uniform, stable, hollow-cone-shaped spray pattern.

The mixture formation itself is also enhanced by turbulences at the edges and inside the cone-shaped spray; these suck air particles into the fuel spray, forming an optimally ignitable mixture.

The microsecond response times of the piezoelectric injectors provide the basis for delivering multiple injections per compression stroke, and thus for lean-burn operation. By allowing flexible and efficient control of the combustion process they play a key part in ensuring the engine’s improved fuel efficiency.

With the aid of simulations for the fuel mixture and the combustion process, the pistons have been designed with special piston bowl geometry which concentrates the lean mixture in the area around the spark plug and prevents it from spreading out towards the cylinder wall. The piston shape therefore also plays its part in ensuring near-total combustion, low fuel consumption and low emissions in the direct-injection petrol engine.

A high-pressure pump and downstream fuel rail and pressure control valve are responsible for delivering the fuel and regulating the quantity supplied. The peak fuel pressure in this system is up to 200 bar—around 50 times the fuel pressure in a conventional gasoline injection system.

The pump delivers fuel to the rails during every second injection, building up maximum pressure. As fuel is only delivered on every second injection the pressure is slightly reduced during the cycle, however the mean pressure for all injectors remains at 200 bar during injection.

A regulating valve ensures that only the fuel quantity required for the engine’s operating point is delivered, thereby reducing the power requirement of the high-pressure pump.

Fuel that is not needed flows back via a water heat exchanger and is mixed with the incoming fuel from the tank of the CLS 350 CGI. The low-temperature coolant circuit of the injection system also cools the electronic control unit of the direct-injection engine, which manages all the working processes of this six-cylinder power unit.

Spark plugs. Correct positioning of the spark plugs was a challenge requiring sophisticated flow calculations and tests. To ensure that the ignition spark is able to jump rapidly and reliably, the spark plug must reach the cloud of fuel/air mixture but must not be in direct contact with the liquid fuel, otherwise it will gradually carbonize.

In order to meet both requirements, the piezo-injector of the CGI engine extends into the centre of the combustion chamber. It has therefore been moved roughly to the position where the spark plug is located in a conventional port-injection engine; the spark plug has been repositioned closer to the exhaust valves, where it can reach the ignitable mixture at the turbulent edges of the cone-shaped spray. A cross-flow cooling system in the cylinder head ensures that the spark plugs and injectors always operate in the most favorable temperature range.

The aftertreatment system. Click to enlarge.

Emissions. The emission control strategy of the new CGI engine is based both on in-engine measures to deliver low engine-out emissions and on effective exhaust gas aftertreatment by a total of four catalytic converters.

The in-engine measures include the Mercedes-developed combustion process featuring multiple closely spaced injections on each compression stroke. This improves the exhaust quality of the V6 engine in the warm-up phase, as actively controlled injection and combustion using low quantities of fuel ensures higher temperatures in the exhaust manifold and accelerates catalytic converter warm-up.

Measurements show that engine-out hydrocarbon emissions in the warm-up phase are almost halved. Furthermore, since the injection and combustion processes can be actively controlled, it is also possible to raise temperatures in the exhaust manifold and thus speed catalytic converter warm-up. Just ten seconds after starting from cold, the direct-injection petrol engine reaches an exhaust temperature of over 700º C.

Aftertreatment begins with two close-coupled three-way catalytic converters, each of them monitored by two oxygen sensors—a control sensor and a diagnostic sensor. This linear oxygen sensor control goes into operation immediately after the engine starts from cold, providing information about the exhaust gas constituents which the electronic control unit of the V6 uses for a controlled warm-up.

To reduce nitrogen oxide emissions, Mercedes-Benz first uses dual electrically controlled and cooled exhaust gas recirculation (EGR) which, depending on engine operating conditions, redirects up to 40% of the exhaust gases back into the cylinders.

Secondly, it also uses underfloor NO_x storage-type catalytic converters. Under lean operating conditions, these converters adsorb the oxides of nitrogen. Periodically, during brief regeneration pulses, the nitrogen oxides are then desorbed, reacting with other exhaust gas constituents to form harmless nitrogen. The NO_x storage-type catalytic converters are also monitored by sensors—a temperature and a nitrogen oxide sensor.

As conventional catalytic converters require a stoichiometric fuel-air mixture (lambda = 1), but stratified charge operation uses high excess air (lambda >1), the CLS 350 CGI is equipped with two NO_x storage-type catalytic converters.

Other engine technologies. The CGI is based on the port-injected V6 first introduced in 2004. Other engine technologies featured on the engine include:

• Variable camshaft timing on the intake and exhaust sides improves the available output. The camshaft angles are adjustable by anything up to 40 degrees to ensure that the valves are able to open and close at the most favorable time in any driving situation.

• A variable intake module varies the air supply as required. The length of the intake ducts leading to the cylinders is adjusted by means of flaps: at lower engine speeds the flaps are closed to increase the length of the intake duct. This creates pressure waves which support the intake process and make a lasting improvement to the torque yield in the lower engine speed range. As a result 317 Newton metres—around 87 of the maximum torque—is already available from 1500 rpm.

• Fuel economy is improved by an intelligent thermal management system. Coolant circulation is stopped during the warm-up phase, so that the engine reaches its normal operating temperature more rapidly. The result is an improved oil flow and considerably less in-engine friction, as well as lower exhaust emissions. When the warm engine is operating under full load, the thermal management system always keeps the engine oil and coolant at the best possible temperatures. This ensured by an electronically controlled thermostat which is active in all driving situations.

• Aluminum cylinder head and crankcase.

• The cylinder liners are surfaced with a low-friction aluminium-silicon alloy. which has proved its worth in other Mercedes-Benz car engines. Other advantages include high dimensional stability, exemplary thermal characteristics and low weight. The weight-saving compared with conventional grey cast-iron liners is around 500 grams per cylinder.

• The forged crankshaft is equipped with four counterweights. Four wide crankshaft bearings with transverse reinforcing struts attached to the crankcase also help to reduce vibrations. A balancer shaft between the two cylinder banks compensates the free vibration moments which are inherent to a V6 engine, ensuring exemplary smooth running. It counter-rotates at the same speed as the crankshaft.

The new CLS 350 CGI is designed to operate on sulfur-free unleaded premium fuel. In Western Europe, the CLS direct petrol injection model will replace the current CLS 350.

Hydrogen Storage in Organic Polymers

In another approach to developing a viable on-board storage system for hydrogen in vehicles, researchers in the UK have developed a purely organic polymer with microporous structures that can adsorb hydrogen via physisorption.

Research into using a microporous material for hydrogen storage tends to focus on materials such as zeolites or activated carbons, which have many molecular-size holes suitable for the containment and release of hydrogen.

By contrast, the molecular chains in most organic polymers are so flexible that they can form tightly packed structures. This means there are no cavities inside, and thus no appreciable internal surface onto which substances could be adsorbed.

The chemists constructed polymers from interlinked five- and six-membered rings. At defined points in the molecule, two five-membered rings are connected in such a way as to provide a contorted shape to the stiff macromolecular structures. The contorted molecules cannot pack together efficiently and leave gaps and interstices.

In reproducible synthetic steps, the researchers have produced chemically homogeneous materials—“polymers of intrinsic microporosity”—with a uniform distribution of pore sizes of 0.6–0.7 nm.

These ultrasmall pores can absorb and then release between 1.4 and 1.7% hydrogen by weight at liquid nitrogen temperatures. Depending on the selection of building blocks the researchers can produce insoluble networks or polymers that are soluble in solvents and can thus be processed into useful shapes.

The current rate of storage is far below the DOE target of 6% for 2010 and 9% by 2015.

In order for the PIMs to store enough hydrogen to be useful they must be optimized further by both chemistry and polymer processing techniques. Neil McKeown of Cardiff University, one of the researchers, estimates that by 2010 they will have tailored a PIM capable of storing up to 6% hydrogen.

Resources:

• “Towards Polymer-based Hydrogen Storage Materials: Engineering Ultramicroporous Cavities Within Polymers of Intrinsic Microporosity”; Neil B. McKeown, Bader Ghanem, Kadhum J. Msayib, Peter M. Budd, Carin E. Tattershall, Khalid Mahmood, Siren Tan, David Book, Henrietta W. Langmi, Allan Walton; Angewandte Chemie International Edition 2006, 45, 1804, doi: 10.1002/anie.200504241

• UK Royal Society of Chemistry: Stirring up High Hopes for the Hydrogen Economy