I know you've probably never heard of micro-hybrid, but they're just conventional cars with the same kind of start-stop technology that's already on most hybrids. At stoplights, the micro-hybrid's gas engine shuts off to save fuel, and then is rapidly restarted. That's easy in hybrids with big battery packs, but harder in standard gas cars unless the 12-volt battery gets some help. Energy-storing ultra-capacitors, cousins to batteries that can charge up and deliver a big boost of power to start an engine or provide acceleration, provide that assistance.
The potential role of ultracaps in electrifying the automobile has generally been overlooked in the U.S., even though many of the pioneers in the field are American. But it's likely to be a huge field in just a few years, because ultracaps can do many things that batteries can't. And the two integrate extraordinarily well.
On Wednesday, Maxwell Technologies will announce that major European automaker PSA (which includes the CitroÃ«n and Peugeot brands) is intending to build up to one million cars with start-stop "micro-hybrid" technology that includes its ultracapacitors. But Maxwell CEO David Schramm insists that its first announced agreement with an automaker (in partnership with major European auto supplier Continental AG) is only the beginning of what is likely to be a bright future for ultracaps on both sides of the ocean. "Continental is a pimple compared to what's coming," he said.
Start-stop can increase fuel economy by as much as 15 percent, and ultracaps can restart the engine in 400 milliseconds. The first PSA cars with Maxwell ultracaps will be CitroÃ«n C4 and C5 diesel models, but Peugeot-badged e-HDi diesel cars will also benefit from start-stop. Continental spokesman Bernd Neitzel said the company was motivated by its "desire to do our part to reduce consumption and lower CO2 emissions," but the European Union will require 65 percent of a carmaker's fleet to reach 130 grams per kilometer by 2012, and 100 percent from 2015 onwards. For 2020, the goal reaches 95 grams per kilometer. Failure to comply means big per-car fines (starting at five euros for the first gram per kilometer the manufacturer exceeds the requirement).
Diesel engines are inherently more fuel efficient than their gas cousins, but their higher compression ratios mean it takes more power to start them -- a role well suited for ultracaps, which also have the benefit of reducing the need for a large battery. "Ultracapacitors aren't of much use just by themselves," said Ted Bohn, an auto engineer at the Argonne National Laboratory. "But when you couple them with lithium batteries, they dramatically boost the performance of the whole vehicle."
Bohn said that ultracapacitors have power density hundreds of times greater than lithium-ion batteries. And he said they can greatly reduce costs by helping "transform an $8,000 battery into a $4,000 all-electric drivetrain system."
Reducing CO2 requires improving fuel economy, so it's not surprising the European carmakers are scrambling for reductions. But it's not only Europe -- green groups in the U.S. would like to see federal fuel economy/greenhouse gas rules cars reach 60 mph by 2025, which would also mean very low grams per mile.
The EPA has been slow to recognize the benefits of start-stop, and that has cooled carmakers' enthusiasm for them in the U.S. Other factors include: Americans like air conditioning (which needs a lot of power to run at stoplights), and also automatic transmissions that don't integrate with start-stop as well as the manuals popular in Europe do.
But Schramm says these obstacles will be overcome, and he forecasts a bright future for the ultracap industry. Maxwell's revenue from ultracapacitors was up 47 percent in the second quarter. "It just makes sense," he said. "PSA can save 15 percent in fuel consumption, and reduce its CO2 per kilometer from 139 to 129 [meeting the 2012 EU target]. And using this technology means PSA can use a smaller battery that will fit under the hood instead of being relocated to the trunk."
As Schramm points out, Americans want cars that get 40 mpg but also accelerate to 60 in six seconds. That's hard to do even with start-stop technology, but it's almost impossible without it.
Ultracap applications for cars will grow sharply, but Maxwell gets most of its revenue today from hybrid buses in China (it's already done 2,500) and pitch controls for wind turbines (12,000 so far). Maxwell is an American company, but its ultracaps are manufactured in China by Lishen (also the battery partner for Coda Automotive) and Belton.
The EPA may not adopt rules requiring 60 mpg by 2025, but it will probably go to at least 50 mpg, and that in itself will be a big impetus for start-stop and ultracaps. The technology has been best described as "promising" up until now, but its potential is rapidly being realized.