Germans create ‘free-piston’ multi-fuel engine that could answer EV range-anxiety issues

piston-free generator

The Germans never cease to amaze us.

A group of scientists at the German Aerospace Center (DLR) have developed what they called the “free-piston linear generator” or, in German, the “Freikolbenlineargenerator.”

In distinctly German form, the name is an entire sentence squished into a single word and not a satirical joke as we had hoped. The ingenious electricity generator is small, lightweight, and ideal for a range-extending application in an electric vehicle – and who knows what else.

piston-free generator close up

Comprised of two pistons inside a single cylinder facing one another, the pistons are fired simultaneously; the kinetic energy of the combustion is used to generate electricity. The opposing boxer-type movement of the pistons also means the engine offsets much of its own vibration for smooth operation.

  • More tech details and a concept video (in German) are here

In place of a traditional crankshaft and connecting rod, there is a gas spring behind each piston. This gas spring can be used to adjust the compression ratio on the fly. The ratio and combustion chamber size can be adjusted so minutely as to accommodate movements down to one tenth of a millimeter. This allows the piston-free generator to run anything from gasoline to diesel to natural gas to hydrogen.

piston-free generator in car

This sort of flexible electricity generation makes the free-piston generator perfect for electric cars that require a range-extending onboard generator. The Chevrolet Volt, for example, has a 1.4-liter inline four-cylinder gasoline generator that fires up after the initial 38-mile all-electric range is depleted.

Right now the free-piston generator only exists on a bench in Germany but we wouldn’t be at all surprised if some big-name automaker jumps all over this technology as it could be a small, lightweight solution to many EV problems.

We’ve always joked that the Germans were magic. With the unveiling of this “free-piston” generator, we now know they are.

Product Review

BMW’s smallest M car is its biggest performance statement

The BMW M2 Competition is frighteningly quick in a straight line, and its short wheelbase lends itself to some hilarious power slides, but it’s the curvy roads and tight tracks where this coupe comes alive.
Cars

Electric car buying guide: What you need to know before you buy

EVs are better than they've ever been, but buying your first battery-powered car can be an intimidating experience. Digital Trends has compiled a comprehensive guide that walks you through the process of buying an EV.
Cars

From rugged wagons to hot sports cars, the 2019 NY Auto Show brought it all

From city cars to supercars, anything goes at the New York Auto Show. Automakers from all over the globe traveled to the 2019 show to unveil their newest concept cars and production models.
Smart Home

Miele stuns with wireless probe, self-descaling java pot, and other new products

Miele rocked KBIS 2019 with waves of new appliances and features. The annual Kitchen and Bathroom Industry Show is all about product launches and Miele's appliance reveal was like New York Fashion Week with a single designer.
Cars

Drywall or kayaks? The 2020 Toyota Highlander is ready for your weekend plans

Toyota introduced the 2020 Highlander ahead of its public debut at the 2019 New York Auto Show. The fourth-generation Highlander is bigger than its predecessor, and it comes with more tech features, including Android Auto and Apple CarPlay.
Cars

2020 Nissan 370Z Special Edition celebrates 50 Years of the Z car

Nissan is celebrating 50 years of its iconic "Z car" with a special edition of the 2020 370Z. The 50th-anniversary model is dressed to look like a 1970s race car, but remains technically unchanged.
Cars

Tesla rushes investigators to China to figure out why a parked Model S exploded

Tesla has sent a team of in-house investigators to Shanghai to determine why an early Model S suddenly exploded and caught fire. The electric sedan was parked before the fire started, and the cause of the blaze remains unknown.
Cars

Google Maps now shows EV owners which charging stations are occupied

Google has just beefed up its Maps app with extra data to help EV owners find the nearest charging station. Drivers can also find out about the number and types of ports available, and whether they're occupied.
Digital Trends Live

Digital Trends Live: Tesla taxis, NYC auto show, and Sony’s 8K TV

On the latest episode of DT Live, we discuss Tesla's autonomous taxi plans, a Face ID lawsuit against Apple,, choosing imperfect produce, the release of Mortal Kombat 11, sustainable fashion, and more.
Cars

Keep your driving record squeaky clean with these top-flight radar detectors

Nobody likes getting a speeding ticket, but these gadgets can help. Check out our picks for the best radar detectors on the market, from the likes of Valentine One, Escort, and Beltronics.
Buying Guides

The best hatchbacks for 2019 are small in size and big on tech

The hatchback segment isn't huge, but there are still plenty of good options to choose from. Here, we've rounded up the best hatchbacks available in America, whether you're a fan of efficiency or looks.
Apple

WWDC 2019 Complete Coverage

Apple’s Worldwide Developer Conference is a key tech event each year, and for Apple fans, it will be one of the two best times of 2019 (along with "new iPhone day," of course). For the last few years, Apple has debuted much of its…
Cars

GPS units aren't dead! Our favorite models still do things your phone can't

Love hitting the open road but hate having to rely solely on your phone for getting around? Thankfully, the best in-car GPS systems will allow you to navigate and capitalize on a range of features sans your cellular network. Here are our…
Cars

Tesla Model S and Model X charge faster and go farther with the same battery

An all-new drivetrain for the Tesla Model S and X enables the EVs to travel farther per charge than the previous design. Tesla Model S Long Range sedans have a 370-mile range and Model X Long Range SUVs can travel 325 miles per EPA cycle.