Not All Hybrids Have Electric Motors and Batteries

Three hybrid innovations to watch

Engineers at the CCEFP are developing a Ford F-150 that delivers 70 mpg and meet California emissions standards. Ford Motor Co.

When it comes to transportation, hybridization is not new. Hybrid cars and trucks that combine an electric motor with a gasoline engine date back to the turn of the 20th century. Hybrid diesel-electric locomotives have been in operation for years, and in the 1970s, small numbers of diesel-electric buses began to appear. On a smaller scale, a moped is a hybrid — it combines the power of a gasoline engine with the pedal power of the rider.

So, any vehicle that combines two or more sources of power is considered a hybrid vehicle (HV). Today, when hybrid and vehicle are used together — think Toyota Prius, Ford Fusion Hybrid or Honda Civic Hybrid — that vehicle, according to the U.S. Department of Energy, is a hybrid electric vehicle (HEV). Each of these vehicles combine an internal combustion engine (ICE) and an electric motor that receives electricity from a battery pack.

Today’s gasoline- and diesel electric hybrid systems are very complex, high-tech wonders in design and operation. Components include controllers, generators, converters, inverters, regenerative braking and, of course, a battery pack — either nickel-metal hydride or lithium ion.

HEVs offer benefits that their conventional gasoline or diesel counterparts do not have — increased fuel economy and fewer harmful emissions coming out the tailpipe. But to achieve the same results not all hybrid vehicles require electric motors and batteries.

Here’s a look at three alternative hybrid systems. One is now employed in big trucks and could find its way into cars, one is likely to appear in a 2016 BMW and the third could be on the road in three years.

Hydraulic — Not Just For The Big Dogs

Last August I featured an article about a hydraulic hybrid system that has made its way into big diesel refuse trucks, the ones that come around once a week and pick up our trash. On a good day, a garbage hauler will eke out 4 to 5 mpg. Then there are all those icky, nasty pollutants pouring out of the exhaust stacks.

But thanks to the United States Environmental Protection Agency (EPA), yes, those same government folks who monitor environmental laws and fuel mileage testing, a hydraulic hybrid system they pioneered increases fuel economy in the big rigs by as much as 33 percent and reduces carbon dioxide (CO2) by 40 percent.

The principal of the hydraulic system is similar to a HEV. It recovers a portion of the energy normally lost as heat by the vehicle’s brakes. But instead of a battery pack, a hydraulic system uses pistons to capture the wasted energy by compressing nitrogen gas stored in a tank, called an accumulator.

When the driver lets off the accelerator pedal, the wheels drive a hydraulic pump that pumps hydraulic fluid to compress the nitrogen gas and slows the truck down. When the driver accelerates, the nitrogen is allowed to expand and pushes a piston in a cylinder filled with hydraulic fluid. This action assists the diesel engine in turning the rear wheels.

The hydraulic system performs remarkably well on the big dog trucks, but what about light duty trucks or passenger cars? The Center For Compact and Efficient Fluid Power (CCEFP), a National Science Foundation Engineering Research Center in Minneapolis, Minnesota is working on that.

The center’s “Generation 2” vehicle — a Ford F-150 pickup — utilizes a custom-built continuously variable power split hydraulic transmission. It is complemented with hydraulic accumulators to enable hybrid operation.

To be competitive, the system must demonstrate advantages over BEVs. Design specifications for the vehicle include: vibration and harshness comparable to a passenger vehicle; a 0 to 60 mph time of 8 seconds; climb a grade of 8 percent; emissions that meet California standards; and the big one, fuel economy of 70 mpg under the federal drive cycles.

Steaming Along

Twin brothers Francis and Freelan Stanley, inventors of the Stanley Steamer, would likely approve of BMW’s innovative use of the same principal that worked to power their steam engine cars more than 100 years ago to improve the efficiency in modern vehicles. Called Turbosteamer, this system uses wasted heat energy from an engine’s wasted exhaust gases to contribute power to the automobile.

This steam assist system starts with a heat exchanger located between the engine and the catalyst that turns water into steam. The pressurized steam is then carried to what is essentially a small steam engine. A second, smaller steam engine produces a little more mechanical energy.

I began following this technology in 2005 when BMW said the two steam engines combined generated 14 horsepower and 15 pounds-feet of torque on a 1.8-liter four-cylinder engine. Additionally, fuel economy improved by 15 percent in overall driving.

The automaker also said it intended to make the Turbosteamer ready for volume production in a number of its vehicles within a decade. Well, it’s 10 years later, will it see production?

Since then, researchers and engineers focused on reducing the size of the components and making the system simpler to improve dynamics. They came up with an innovative expansion turbine based on the principle of the impulse turbine. The system is now smaller, costs less and the developers say fuel consumption is reduced by up to 10 percent during highway driving.

While the Turbosteamer can’t compare its greenness to the BMW i3 all-electric car, a 10 percent improvement in fuel economy for an “Ultimate Driving Machine” is nothing to sneeze at. It’s possible a Turbosteamer equipped BMW vehicle will be introduced next year.

Not Just A Bunch Of Hot Air

The idea that compressed air could power a viable zero emissions car has been pursued for years by many respected engineers. In 2000, there was much ado about a new compressed air, zero pollution vehicle from French inventor and Formula One engine builder, Guy Nègre. His company, Motor Development International (MDI), rolled out an urban-sized car, taxi, pickup and van that were powered by an air engine. Instead of those tiny, tiny explosions of gasoline and oxygen pushing the pistons up and down, like in a normal internal combustion engine, the all-aluminum four-cylinder air engine used compressed air for the job.

A hybrid version, using a small gasoline engine to power an onboard compressor for a constant supply of compressed air, was claimed to be able to travel from Los Angeles to New York on just one tank of gas.

In 2007 MDI signed an agreement with Tata Motors, India’s largest automobile manufacturer to produce air cars in 2008, followed by the hybrid version in 2009. No cars were produced. That’s perhaps one of the reasons compressed air-powered cars have been the butt of jokes among the green car community.

Today, the number of jokes has diminished. That’s the result of Peugeot’s introduction of the 208 HYbrid Air 2L Prototype at the 2014 Paris Auto in October. (Full Review). It employs a compressed air tank that turns a hydraulic motor for additional power or zero emissions city driving rather than a battery for the same functions.

Like a BEV, during normal driving the car is powered by the gasoline engine. Compressed air is called upon for additional power when passing or traversing a hill. In this situation, power from both the engine and hydraulic motor are directed to the front wheels via an epicyclic transmission, similar to the planetary gear set transmission used by the Toyota Prius.

In city driving, where less power is needed and emissions-free driving is the priority, rather than power provided by a battery, the compressed air alone motivates the car. The compressed air tank is recharged when braking or by using part of the energy developed by the three-cylinder gasoline engine to compress the air.

During the Pairs Show, Peugeot said if another large auto manufacturer would buy into the technology to enable production in enough numbers to assure manufacturing affordability, the HYbrid Air could be on the market in three or so years. Two reports from Europe are suggesting, without naming the car company, that Peugeot has found an interested partner.

Last Word

It’s not certain that any of these three alternative hybrid systems will be available in production vehicles, and if they are, what kind of an impact they will have in the marketplace. What is clear is, electricity in the drivetrain isn’t the only way to hybridize a vehicle.