New OPOC
engine developments are causing a resurgence in interest in the engines. They
offer the possibility of significant efficiency gains, possibly making them the
green engine of the future.
The
opposed piston opposed combustion- OPOC for short - engine may just shake up
the automotive world. Interest in the engine has been brewing for years, and
recently burst over when Bill Gates announced his $23.5 m investment in EcoMotors'
OPOC engine design. The reason for Gates's, and the world's, attention is the
incredible OPOC engine efficiency. It is claimed that the engines are up to 50%
more efficient than a typical internal-combustion engine, while at the same
time are smaller and more powerful than Stirling engines. This combination of
power and efficiency may make OPOC engines the technology of the future for
hybrid cars.
The OPOC engine is an internal combustion engine, so it isn't emissions-free. The engine, as designed by Ecomotors International, consists of two cylinders, each with two opposing pistons. The two pistons in each cylinder run in opposing directions, and hence there is no cylinder head. This allows a significantly smaller engine to be produced, one that uses only about half the number of parts as a typical four-stroke engine.
In
contrast to typical automotive engines, the OPOC is a two-stroke engine.
Two-stroke engines make a complete cycle with two piston movements, as opposed
to four in four-stroke engines. They accomplish this by combining several steps
in each piston movement: intake and exhaust are taken simultaneously during the
initiation of the compression stroke and at the completion of the combustion
stroke. This allows the engines to output very high power for their weight.
Though
two-stroke engines are very efficient, engineers have long disregarded them in
cars for environmental reasons. Opposed piston diesel engines were popular for
a time, and were used in ships, aircraft, and small automobiles. However, the
engines had a seemingly unavoidable emissions problem: they release both
unburned fuel and oil in the exhaust, creating higher emissions than
four-stroke engines. One of the major accomplishments of the Ecomotors team
has been to resolve this emissions issue. By eliminating or reducing these
emissions, the company has created an engine with much higher power density
than typical engines. The company's website states that the engine creates more
than one horsepower per pound. They have also eliminated the need for cylinder
caps and drive trains, produced reduced emissions, and provided increased
efficiency.
The
engine's two-stroke design makes it significantly more efficient than
conventional engines. The OPOC diesel engine designed by Ecomotors is
"30-percent lighter, one-quarter the size, and achieves 50-percent better
fuel economy compared with a state-of-the-art, conventional turbo-diesel
engine," as stated on the company website.
The
company expects to demonstrate a 100 mpg passenger car by late 2010, which
would be a large improvement over today's hybrid cars. Due to the engine's
small size, it may also end up finding use in hybrid cars, which operate both
combustion and electric engines.
Below, find some
specifications of an OPOC engine, the diesel fuel EM100. The engine family is
expected to include diesel, gasoline, and ethanol engines.
○ Dry weight: 296
pounds
○ Dimensions: 22.8 x
41.3 x 18.5 (inches), Length x Width x Height
○ Cylinder bore:
100 millimeters
○ 325 horsepower at
3500 rpm.
○ Torque: 664 pound
feet at 2100 rpm
○ Power density: 1.1
horsepower/pound
After
reading about the extreme efficiency provided by OPOC engines, readers may
begin to wonder how much the cost will be for an OPOC engine. This is a fair
question, since other energy efficient engines have proven to be very
expensive. Though no price point has been released yet for OPOC engines, there
is good reason to expect them to be inexpensive. Unlike electric engines,
two-stroke OPOC engines are constructed out of conventional parts. This means
that companies won't need to purchase expensive parts or, worse yet, custom
order them. The engine's small size and simplicity is another advantage: Ecomotors states
that the engine has only half the parts of a conventional engine. This saves on
expense and labor,
and should bring the price down.
The OPOC
engine efficiency and simplicity should also make it durable, saving owners
maintenance cost in the long-term. After years of false starts in green engine
claims, the OPOC engine just may be the real McCoy.