Flywheel Hybrids

The Separation Of Tasks

Let's review for a moment the conventional engines found in most vehicles. First, there needs to be sufficient power for strong acceleration. Then, when the vehicle is cruising near 60 -70 miles per hour, it must convert the gasoline into forward motion as economically as possible. However, for strong acceleration, the engine would have to be of sufficient size but a smaller engine is better for cruising. This is where a conventional engine makes the compromise for a size that falls somewhere in between.

Current hybrid vehicles contain two separate power units instead of just the one found in conventional car engines. Each power unit is designed to do one of these tasks - that is acceleration at low speeds and the other for running efficiently at high speeds. This set up is far more effective than how a conventional engine handles this. Hybrid car manufacturers believed that customers would be willing to pay the premium for the two separate power units for its capability to handle both requirements of acceleration and economical engine use while the vehicle is cruising. Also lower fuel consumption would be another attractive point to make the premium worthwhile to customers. Well, they were right and the sales figures of hybrids have borne out.

Energy Supply versus Surge Power

There is a lot of talk among hybrid engineers about Energy Supply Units and Surge Power Units. Energy Supply Units can be gas engines or diesel engines. Bio-fuel engines, fuel cell systems, gas turbines, and even plug-in batteries fall under the same category. There have been several heated discussions over what the best choice for a particular implementation. Surge Power Units for acceleration come from the hybrid batteries. If your vehicle approaches a stop sigh or a red light, you gently hit the brake pad to bring the vehicle to a stop. In vehicles that have conventional engines all of the energy of motion caused from road speed and car weight is sent out as heat energy from the brakes. On the other hand, the Surge Power Unit in hybrids collects as much energy from the car's motion as possible. This collection of energy causes the vehicle to slow down and at the same time reserving the brakes for an emergency stop. The Surge Power Unit stores that energy, until the vehicle moves, when the available energy from the Surge Power Unit is used in instead of fuel-energy from the engine.

The Electric Battery Storage Problem

This energy from the hybrid vehicle's motion described above is called kinetic energy. This type of energy saving can significantly reduce how much fuel the vehicle consumes. However, the battery-based solution seems to ignore the basic physics of the application. The key task of the Surge Power Unit is to, as described above, collect as much of the vehicle's kinetic energy as possible and recycle it as kinetic energy later.

In physics, the Second Law of Thermodynamics explains that transforming energy from one form to another creates significant losses. This is the reason why battery-based hybrid drive systems are not as efficient. In hybrids based on an electric battery, there are four energy-draining processes for every regenerative braking cycle:

Kinetic energy is changed into electrical energy. Afterwards, the electrical energy is changed again into chemical energy as the battery charges. When the electrical battery discharges, there is yet another transformation of chemical energy into electrical energy. Lastly, the electrical energy goes into the vehicle's motor or generator acting as a motor, which is changed once more into kinetic energy. These four transformations are not efficient.

Are Flywheels A Solution?

How can we avoid the four energy-draining processes? To do this the energy has to retain the same form when the vehicle starts braking - no transformations. There must be a way to use the energy without converting it constantly. It is the conversion of kinetic energy that causes the loss. This will also follow the Second Law of Thermodynamics and increase efficiency.

High-speed flywheels are used in space and in power supplies for computer systems. They are not used widely in automobiles. High-speed flywheel energy is a system where the inputs and outputs have to be electrical currents. Flywheel systems are meant to be a substitute for electrical battery systems. The use of flywheel technology is well known.

Issues With Flywheels Examined

Generally speaking, a mechanically driven flywheel system experiences loss due to bearing friction, wind and other factors which actually make flywheel systems less efficient than a hybrid's battery-based system. The battery based system stores energy for more than an hour or so but over much shorter periods required in stop and go city traffic a mechanically driven flywheel is actually more effective. Based on this, the best combination is a plug-in hybrid and a flywheel system as the Surge Power Unit. In addition, throw in an electric battery to store electrical energy efficiently. What do you have? The flywheel Surge Power Unit protects the battery from load caused by acceleration and braking. It also ensures a longer battery life and allows the battery to run far more efficiently.

Engineers are now using the high-speed flywheel idea and applying the concept to full-sized vehicles. The Surge Power Unit's efficiency is at least 60-80% or more with continued development. This means that a flywheel system if implemented correctly can significantly improve fuel economy, without sacrificing acceleration. It also does this at a substantially lower cost.

Back To Car Facts Articles