January 18, 2012
Car Friction Reduction Could Save Substantial Energy

A third of your gasoline goes toward overcoming friction. Over half of that friction might become avoidable within 15 to 25 years.

No less than one third of a car's fuel consumption is spent in overcoming friction, and this friction loss has a direct impact on both fuel consumption and emissions. However, new technology can reduce friction by anything from 10% to 80% in various components of a car, according to a joint study by VTT Technical Research Centre of Finland and Argonne National Laboratory (ANL) in USA. It should thus be possible to reduce car's fuel consumption and emissions by 18% within the next 5 to 10 years and up to 61% within 15 to 25 years.

There are 612 million cars in the world today. The average car clocks up about 13,000 km per year, and in the meantime burns 340 litres of fuel just to overcome friction, costing the driver EUR 510 per year.

Electric cars lose far less of their energy to friction. So they have less to gain from friction reduction. So reduced friction loss will improve the relative advantage of cars buring liquid hydrocarbon fuels versus electric cars.

Of the energy output of fuel in a car engine, 33% is spent in exhaust, 29% in cooling and 38% in mechanical energy, of which friction losses account for 33% and air resistance for 5%. By comparison, an electric car has only half the friction loss of that of a car with a conventional internal combustion engine.

Annual friction loss in an average car worldwide amounts to 11,860 MJ: of this, 35% is spent in overcoming rolling resistance in the wheels, 35% in the engine itself, 15% in the gearbox and 15% in braking. With current technology, only 21.5% of the energy output of the fuel is used to actually move the car; the rest is wasted.

One thought: on shorter trips it should be possible to avoid the need for a cooling air conditioner and gasoline power lost to it. Imagine when parked you could plug in the car and the electric power would operate a condenser to super cool some liquid. Then that frozen material could provide a source of cooling for, say, an hour or two.

Newer materials can cut friction. But what about the costs?

A recent VTT and ANL study shows that friction in cars can be reduced with new technologies such as new surface coatings, surface textures, lubricant additives, low-viscosity lubricants, ionic liquids and low-friction tyres inflated to pressures higher than normal.

Friction can be reduced by 10% to 50% using new surface technologies such as diamond-like carbon materials and nanocomposites. Laser texturing can be employed to etch a microtopography on the surface of the material to guide the lubricant flow and internal pressures so as to reduce friction by 25% to 50% and fuel consumption by 4%. Ionic liquids are made up of electrically charged molecules that repel one another, enabling a further 25% to 50% reduction in friction.

The payback will come faster in commercial vehicles that travel great distances every year. So are diamond-line carbon materials getting designed into engines or transmissions of any long distance trucks today?

Share |      Randall Parker, 2012 January 18 11:14 PM  Energy Transportation

Kentucky said at January 19, 2012 6:45 AM:

Just cooling or warming the car before getting into it saves plenty of energy because the system doesn't have to work as hard to keep the people comfortable.

ENC said at January 20, 2012 2:53 AM:

When I used to have to drive to work, few years ago now so before electric cars were really hitting their stride, I used to carpool with 3 folks from work. You're right in fixing the root cause is clearly the goal, but even folk that can't afford an new car can help themselves, their bank balance and the environment if they can carpool.

Even alternating cars with just one person local to you works out cheaper for both of you!

solaris said at January 20, 2012 10:33 AM:

I guess what they mean here is "mechanical friction in the engine and drivetrain", since close to 100% of your gasoline's energy is used up on friction in general - the rolling resistance of the tires, air resistance, etc.

Jeff Radtke said at January 20, 2012 11:15 AM:

I agree 100% with solaris. Virtually all of the fuel energy becomes thermal in form. Evaporation is the only non-thermal loss I can think of, and the evaporated fuel may eventually be oxidized outside of the vehicle. If there could be a magical frictionless vehicle, it would take zero energy to move from place to place, since even the energy to accelerate could be recovered upon deceleration.

The time integral of conversion efficiency from fuel thermal energy to payload kinetic energy is the residence time of fuel energy and a convenient way to quantify overall transportation performance.

Jeff said at January 20, 2012 11:14 PM:

"Only 21.5% of the energy output of the fuel is used to actually move the car; the rest is wasted."

This statement is clearly wrong. If the car's initial and final velocity are the same (zero), and the car does not change in elevation from origin to destination (and therefore there is no change in gravitational potential energy), then by definition, 100% of the energy is wasted because no work has been done. If low-friction materials are helping to reduce this waste, that's great -- but one has to question the numbers when the authors are seemingly unaware that no phlogiston is lost in your daily commute.

Timba said at August 17, 2013 8:38 PM:

Jeff is wrong
Fuel is spent not onlyfor internal energy (kinetic or potential) but work of moving is also done
A (work)= f (tires resistance)* s (distance)

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