Green Tech

I'm a big fan of "German engineering"--that combined focus on power and precision that distinguishes the better automobiles designed or manufactured in Germany.

At Frankfurt's International Motor Show, BMW will be showing off two new hybrid cars intended to deliver the full promise of German engineering. This is no small thing because most hybrid cars to date have been lightly built and somewhat underpowered in order to improve fuel economy.

The two new BMWs are more like previous offerings from that company: big, solid cars with lots of power to maintain performance in spite of the weight. They're also real cars, not just prototypes.

Fortunately, I don't need to describe these new cars here; there's a great article by Antuan Goodwin over on CNET's Car Tech blog that does a fine job of that (see "BMW unveiling two big hybrid models at Frankfurt"). What I would like to do instead is to drill down into their respective powertrains, which represent two different solutions to high-performance hybrid design, using images provided by BMW.

The ActiveHybrid X6, due to go on sale in the U.S. later this year, represents one end of the spectrum: higher-power electric motors and a larger battery pack. As the first image shows, the new X6 model has a twin-turbo V8 gas engine with 400 horsepower. Though this is a reasonably efficient engine for its size, it certainly wasn't chosen primarily for its fuel economy.

BMW's ActiveHybrid X6 uses a large NiMH battery pack and a new transmission with two integrated electric motors to augment its 400-horsepower gasoline engine.

(Credit: BMW)

The large NiMH (nickel metal hydride) battery pack is also visible in this view, mounted above the rear drivetrain components and below the floor of the luggage compartment. This battery pack holds 2.4 kWh (kilowatt-hours) of energy; BMW also specifies a "nominal" 1.4 kWh figure, but doesn't explain the difference between total capacity and nominal capacity. I suspect the difference may be related to improving battery lifespan, or perhaps provide some extra storage to ensure that electric braking assist (regenerative braking) is always available. BMW does say that this braking mode can generate as much as 50 kilowatts of power and 0.3 g of deceleration force.

In the following view of the X6's transmission, the electric motors are shown built right into a new transmission that BMW describes as an "electric continuously variable transmission"--the electric motors and three planetary gearsets work together to provide the equivalent of seven gear ratios.

The transmission in the ActiveHybrid X6 has two integrated electric motors totalling 177 horsepower.

(Credit: BMW)

Interestingly, with ratings of 91 and 86 horsepower respectively, the two electric motors could provide a total of 177 horsepower, but the vehicle isn't designed to operate that way. BMW specifies a maximum system output for the ActiveHybrid X6 of 480 horsepower, reflecting a maximum contribution from the electric motors of around 80 horsepower.

Part of the issue here is that the battery pack is rated at a maximum output of 57 kW, roughly 76 horsepower, so there isn't enough electrical power to drive both motors at full power. I expect there are also some issues related to heat and torque, but BMW hasn't offered a full explanation of this limitation.

It's also interesting to note that while the new X6 supports a pure electric drive operating mode, it's only good up to 37 mph and 1.6 miles. This figure is well below the energy capacity of the battery pack, probably reflecting more limitations imposed in the name of long-term reliability.

The ActiveHybrid 7, a hybrid version of BMW's 7-series luxury sedan due out in the spring of 2010, takes a very different approach. It has only a small electric motor positioned between the engine and transmission, and it comes with only a small lithium-ion battery pack. The following figure shows that the battery pack is located to the side of the trunk, leaving plenty of space for golf bags. (BMW says that four standard bags will still fit, which I suppose is a critical specification for 7-series customers.)

The ActiveHybrid 7 is powered by a 440-horsepower gasoline engine and a small 20-horsepower electric motor with a lithium-ion battery pack.

(Credit: BMW)

Zooming into the transmission in the following picture, we can see the pancake-style electric motor in front of what appears to be a fairly conventional 8-speed automatic transmission. In its press release, BMW does emphasize that this is a new transmission design "specifically tailored to the demands of hybrid technology," but the release doesn't explain how this gearbox differs from the 8-speed automatics on previous BMW cars.

The ActiveHybrid 7's electric motor is tucked away between the gas engine and a conventional 8-speed automatic transmission.

(Credit: BMW)

The new 7's electric motor produces a mere 15 kilowatts, roughly 20 horsepower. Together with the gas engine, the vehicle's maximum output is rated at 455 horsepower. The electric motor also functions as a starter motor for the gas engine and a generator to charge the two batteries on the car: a conventional 12V lead-acid battery and the 120V lithium-ion pack in the trunk.

The latter is a small pack storing only 400 watt-hours of energy--that's about like eight average laptop batteries. BMW doesn't mention whether the new 7 can run solely on the electric motor, but I doubt it; 20 horsepower probably isn't enough for that. Certainly the range would be negligible given the low battery capacity.

Instead, BMW describes the value of the electric motor in terms of two uses: first, it's powerful enough to restart the gas engine almost instantly (in less than one rotation of the crankshaft) so the engine can be shut down at stoplights, just as the Toyota Prius does. Second, the electric motor provides supplemental power while the gas engine is running, thus improving overall fuel efficiency. Since the battery can be charged by recovering braking energy, the power from the electric motor is often free.

BMW says the hybrid systems in the ActiveHybrid 7 were developed jointly with Daimler, maker of Mercedes automobiles. This partnership also led to some Mercedes models, and indeed, Mercedes has also introduced hybrids with powertrains similar to that of the ActiveHybrid X6. (Mercedes is announcing a new S500 hybrid in Frankfurt but didn't provide such nice pictures, so I didn't include it in this post.)

Both of these approaches will need to be developed substantially before they can reduce the total cost of owning and operating a motor vehicle. But it's clear that BMW, having waited this long to get into the hybrid car business, is giving its customers two very different choices. What the company does in the future will probably depend on how its customers respond.

The FT-HS concept shows what a Toyota hybrid sports car might look like.

(Credit: CNET)

News circulated on the Internet today about a new hybrid Toyota sports car and a hybrid BMW sedan. Spy photos show the BMW 755ih, a hybrid version of the 7-series, driving the streets of Munich. The car uses the 750i's twin turbo 4.4-liter V-8 complemented by a small 20 horsepower electric motor. BMWBlog says the hybrid system reduces the V-8's fuel consumption by 15 percent. The 755ih should be unveiled at the 2009 Frankfurt auto show.

The egmCarTech blog reports that Toyota is working on a hybrid sports car to be released in 2011. Over the past couple of years, Toyota has gone back and forth about this hybrid sports car project, showing the FT-HS concept at auto shows then claiming to halt plans for any performance-oriented car, but the latest reports suggest reviving the Supra as a hybrid. This car would use Toyota's 3.5-liter V-6 along with its Synergy hybrid system to put down 400 horsepower.

(Source: BMWBlog and egmCarTech)

BMW's 7-series concept uses a mild hybrid powertrain.

(Credit: BMW)

Following on the recent announcement by Mercedes-Benz of its mild hybrid sedan with lithium ion batteries, BMW announced its own mild hybrid sedan with lithium ion batteries.

Although it may sound like cutthroat competition, it's more conspiracy, as Daimler and BMW co-developed their hybrid components. And where Mercedes-Benz announced a production car, BMW is still at the concept stage with its Concept 7-series ActiveHybrid. But in keeping with its sport aspirations, the BMW shows no compromise in power, using a twin-turbo V-8 assisted by the mild hybrid system. The twin-turbo V-8 delivers 407 horsepower and 442 pound-feet of torque, while the hybrid system's electric motor, integrated into the transmission, adds 20 horsepower and 155 pound-feet of torque.

The hybrid system was co-developed by Daimler and BMW.

(Credit: BMW)

As a mild hybrid, the Concept 7-series ActiveHybrid can't run under electric power alone--the electric motor merely adds thrust when needed and is an essential part of the idle-stop system. At a traffic light, the engine shuts down to save gas, with the electric motor cranking it back up when the driver hits the gas, and adding its power to make up for the initial shortcoming of the engine. BMW claims a 15 percent improvement in fuel economy.

The lithium ion battery pack sits over the rear axle, and gets recharged through regenerative braking. Along with providing electricity for the motor, this battery pack works as a 120 volt power source for the car's onboard electronics.

BMW has previously shown the X6 ActiveHybrid concept, an SUV using a full hybrid system based on technology co-developed by BMW, Daimler, and GM. We first saw a version of that hybrid system in the GMC Yukon Hybrid. BMW promises two cars using some form of its hybrid technology will reach production in 2009. The company might want to hurry up, as Lexus already dominates the segment for powerful luxury hybrid sedans with the LS 600h.

The electric motor is integrated with the transmission.

(Credit: BMW)

BMW works on making the electric Mini, which sounds like a new dance.

(Credit: CNET)

If you had any doubts about an upcoming era of electric cars, put them aside. BMW announced it is testing electric powertrains in the Mini Cooper. Over the next year and a half, BMW will use a fleet of several hundred Minis to experiment with electric drive systems and, according to the press release, "determine the alternative drive of the future." If any company can do it, it's BMW. There are no current details about what motors and types of batteries BMW will use, but the company promises details by the end of the year.

Audi is joining other German automakers in the effort to eliminate exhaust emissions, promising to bring an electric model to market in the next 10 years.

Rupert Stadler, Audi's chairman and chief executive, said in an interview with German weekly Welt am Sonntag published Sunday that he expects battery technology to dominate in the coming five to 10 years.

"By then we will offer cars without exhaust emissions," Reuters quoted Stadler as saying. "Electric cars offer great opportunities, which we have already seized on."

Reducing vehicle emissions is a chief concern for automakers in Germany. BMW recently showed off a hydrogen-powered 7-series sedan at the 2008 SAE World Congress in Detroit that actually emits less carbon monoxide than are found in the air around it.

At last year's Frankfurt auto show, Mercedes showed off a number of diesel-electric hybrid concept cars that are scheduled for production in 2010 as well as its Diesotto engine, which uses turbo charging, direct injection, and diesel-like compression to maximize power and fuel economy.

Luxury German automakers are likely to be among the hardest hit by new European Commission legislation for stricter emissions and fuel efficiency standards, and consequently have been making efforts to find more efficient versions of their performance-focused lineups.

Tests show minimal emissions from BMW's hydrogen car.

BMW showed off a hydrogen-powered 7-series sedan at the 2008 SAE World Congress in Detroit that actually emits less carbon monoxide than are found in the air around it. This means the engine breaks down or converts the carbon monoxide it takes in. The emissions tests, run by Argonne Laboratories, also show a similar reduction in nonmethane organic gases. The vehicle's other emissions are all so low that standard automobile emissions testing wouldn't have detected them.

This particular demonstration vehicle uses a 6-liter combustion engine that uses hydrogen as fuel, burning it in the cylinders and, according to BMW, delivering performance on par with a standard gas-powered 7-series. Most hydrogen cars from other automakers use fuel cells to generate electricity. Currently, BMW has been handing its Hydrogen 7 sedan, a car with a dual-fuel hydrogen and gas system, over to various celebrities and decision influencers, such as J.D. Power III. But the new demonstration vehicle only uses hydrogen for fuel. BMW doesn't consider the car a prototype, and won't be building more on the same scale as the Hydrogen 7.

BMW's Hydrogen 7 car runs on gas and hydrogen.

(Credit: BMW)

Plug-in hybrids are coming. General Motors, Tesla Motors, Fisker Automotive and Toyota are all coming out with gas-electric cars that can be charged from a socket.

The question now is can the grid handle it. The latest voice on the debate, Stan Hadley of the Cooling, Heating and Power Technologies Program at Oak Ridge National Laboratories, says it won't be easy. Hadley examined 182 scenarios on how plug-ins might be used in different regions in the U.S. between 2020 and 2030. Hadley assumed a 25 percent penetration of plug-ins by 2020.

In a worst case scenario, Hadley postulated that the U.S. would need 160 new power plants to handle the requirements of these cars. The worst case scenario, though, assumes that the millions of plug-in owners would want to charge their car at 5 p.m., the tail end of peak power demand.

In a best case scenario, where drivers charged their cars after 10 p.m. and smart grid technologies staggered charging times, the U.S. would need zero to eight new power plants.

Zero to 160 is a big swing, but Hadley warns that you have to accommodate human nature. Electricity costs less at night, so individuals will be incented to charge their cars then. But you also can't control everyone's behavior.

"It might prove extremely difficult to force consumers to charge their cars during some specified period of time," he wrote in his report. Continued, repeated charging could also stress the infrastructure of the grid, he added.

Overall, Hadley concluded that nearly every region in the country would have to beef up its electrical capacity. Electricity prices would also rise, by 1.2 to 2.7 percent in the best case scenarios to 141 to 297 percent in the worst case scenarios. The price hikes also depend on the size of the batteries used in the cars.

In Hadley's analysis, plug-ins could end up producing more carbon dioxide than efficient standard hybrids. But a plug-in hybrid is always better than driving a regular car.

"The best thing about plug-in hybrids is that they open us up to non-oil," he said in a phone conference. "But there are questions. Hybrids do a pretty good job themselves." Hadley isn't alone in his skepticism of plug-ins. "Plug-in hybrids are irrelevant because they are too expensive. Unless you can make 500 million or 800 million of those, it won't matter," said noted VC Vinod Khosla recently. Plug-ins and electric cars, though, have a lot more adherents right now than detractors. It will take more information and studies to figure out who is right on this one.

Last year, the Pacific Northwest National Labs said that you could convert 73 percent of the cars, trucks and vans on the road in the U.S. to plug-ins and the grid, as it currently exists, could handle it. PNNL scientists, however, said that their study depended on night time charging and that it still needed to study the impact on the grid of sustained charging.

(Credit: BMW)

As we told you last September, BMW has been kicking around the idea of a fourth brand (in addition to MINI, Rolls Royce, and BMW) for a while. This week it emerges that this new addition to the Bimmer family lineup may be a dedicated "green" line of vehicles focused on high fuel economy and lower emissions. If so, the strategy would certainly make sense as it will enable BMW to meet tough environmental requirements without sacrificing too much of its performance-related DNA. BMW is one of a number of premium European brands likely to suffer most at the hands of recent U.S.--and proposed European--legislation to toughen emissions standards and fuel economy.

Last month's passage of legislation requiring increased fleet-wide fuel economy standards to an average of 35mpg by 2020 in the US was followed by confirmation from the European Commission that it had adopted a legislation proposal for emissions and fuel efficiency that requires all new cars to achieve a fleet average of 130 grams of CO2 per kilometer (as a point of comparison, the BMW 335i, by no means the biggest car in BMW's lineup, has a carbon output of 173 to 235 g/km and an average fuel economy of 20 mpg). According to the EC proposal, manufacturers can team up with other companies to meet the emissions target if they are unable to do so on their own, but it looks like BMW is considering building itself an in-house eco-brand to achieve this. The news is the latest in a series of examples we've seen of performance- and luxury European brands scrambling for a green solution, from Porsche's Cayenne and Panamera hybrids to Ferrari's Bio Fuel F430 and Mercedes' S300 Bluetec Hybrid.

Source: Reuters via Just Auto