For years topics relating to the environment and green energy were a social issue, with emphasis on moral and social consciousness rather than on anything practical. It was not an issue to be taken too seriously. Today it has become a social imperative, an issue in which everyone has to actively participate. Whether it is a matter of switching off the lights in unoccupied rooms, turning off the taps while brushing your teeth, or actively investing in renewable energy, energy consciousness seems to be reaching a deeper penetration of the public psyche than ever before.

The subject of renewable energy acquired a much-needed boost recently, in view of the fact that President Obama has openly advocated research into green energy, resulting in a great deal of publicity. After decades of occupying a secondary place in any discussion on energy, renewable energy has suddenly become one of the focal points of public interest.

What exactly is renewable energy? It is an energy resource that can be continually replenished, unlike petroleum, coal, natural gas or other fuels which are used once and then are gone forever. What are the options, problems and drawbacks facing the implementation of renewable energy?

First let us take solar power. What does it have to offer? Solar (photovoltaic) power is almost like the original energy fantasy: you install a solar panel and then for years and years that panel will produce electricity, without any further inputs. That is the fantasy -- the ultimate goal. In actual fact it is much more complicated. A one-meter-by-one-meter solar panel will produce about 60 watts of electricity during peak hours. A one-meter-by-one-meter (three-foot-by-three-foot) panel is quite a large area and the amount of power produced by it is just barely enough to light a 60-watt light bulb during the hours of peak sunlight. So you would need a lot of panels -- a roof full of solar panels, in fact -- just to begin to get the amount of power that a normal household needs. In fact, to produce about 16 kW you will need about 265 sq. m. (11,365 sq. ft.) of panels. So it is not just a question of having adequate storage facilities for the electricity generated by solar panels, but, at 60 watts per sq. m., one of insufficient output.

The biggest drawback of photovoltaic energy is that adequate power is only produced at peak hours during the day while at night everything stops. So, at the moment, solar power is of little help. However, bear in mind that the introduction of LED lighting together with new battery technology such as lithium-ion might go a long way towards making solar, or photovoltaic, energy feasible for at least the partial fulfillment of electricity requirements for domestic use.

Wind-powered turbines are another good source of renewable energy. Here again, location is all-important: if you live in an area where the winds blow at an average speed of about 16 km/hr (10 mph) throughout the year or for at least part of the year, wind power would be a good choice, even if it does have to be supplemented by the grid at times when wind speeds are low. Unlike solar, a windmill can produce power in the kilowatt range, so it is much more efficient. Yet this does not take into account people who live in areas where the wind speeds are low or those who live in cities.

It has to be said that some countries have made quite a success of wind power: Germany produced 22.2 GW of wind-powered electricity in 2008, the U.S. produced 17 GW and Spain 14.8 GW. Still, as a percentage of the total electrical power output it is insignificant; for the U.S. it works out at about one percent, while in Denmark it is about 20 percent. Now look at the size of those turbine blades: a large commercial wind turbine has rotors that are 65 meters across! Two hundred and thirteen feet! Smaller machines might have rotors of about 30 meters (1 00ft.) across, and the heights of the towers range from 40 meters (130 ft.) to 80 meters (260 ft). So wind-powered generation does require a lot of space.

These are two of the better known options when talking about renewable energy. There is another source of renewable energy that has been used by mankind for thousands of years, right from Stone Age to the present day. It played a great part in the Industrial Revolution, and without it our cars would not run today. I am talking about the flywheel. Without it, the great steam engines and locomotives of the eighteenth century would not have run, and without it the internal combustion piston engine could not have been invented.

For many years, thanks to pioneers like Dr. Richard F Post, Professor Andrew Frank and the father-and-son team of Jack and Steve Bitterly, the U.S. has been at the forefront of flywheel energy technology. Dr. Richard Post was originally a nuclear scientist working on fusion energy, and it says much for the potential of flywheels that he has devoted the past 40 years of his life to re-inventing the flywheel and advocating its use in everything from transport to power generation. He has asked for and received over the years more than $150 million dollars for flywheel research, with the result that, today, the technology has advanced to being one of the best researched and documented disciplines. More is known about the performance, structure and working of the flywheel than ever before. Jack Bitterly originally worked on designing top secret military planes, and has also devoted his life to promoting flywheel energy. Bitterly formed the company U.S. Flywheel Systems, while Professor Andrew Frank actually built a flywheel car in the mid-1970s using the regenerative power from braking to power it.

It is a pity then that, like many other inventions, it was the Europeans who first put the technology into commercial use. The well-known Swiss firm Oerlikon produced a gyro bus that was exclusively powered by a flywheel. The massive flywheel that powered these buses, measuring one metric ton, with a one-meter diameter, would be brought up to a speed of 3,000 rpm by fixed overhead powering stations, at which point it possessed a kinetic energy of 6.2 MJ. This was enough energy to power the 11 metric ton bus at speeds of 60 km/h for distances of up to 6 kms (10kms. at a stretch). In other words, once revved up, the flywheel could power the 11-ton bus for six minutes at a time, or for a 10-minutes at a stretch. These `gyro' buses were in commercial use at various locations around the world for almost eight years before finally being de-commissioned in 1958. The Parry People Movers rail car, which works on the same principle, is at present being introduced in the UK over short routes.

The great drawback with the flywheel so far has been that it has needed an electrical motor to bring it up to speed. An internal combustion piston engine works with reciprocal motion and hence needs linear-to-rotary conversion. This makes it unsuited to bringing out the full potential of a flywheel. In order to speed up a flywheel efficiently, an engine with pure rotary output is needed. For instance, flywheels using regenerative braking are powered up by the pure rotary motion of the wheels when braking. The Wankel engine, which is called a rotary engine, in fact has an eccentric output that is even more unsuited for flywheel operation than is an internal combustion piston engine. A flywheel needs a smooth rotary torque to spin up to speed.

The only way in which a flywheel system could be made independent and efficient is if an engine with pure rotary output were available. If such an engine were available, it would be possible to charge the flywheel (or bring it up to speed) onboard, without batteries or external means of charging. This would mean that the vehicle would be extremely light and, further, since the engine would only have to run for a few seconds for each charging of the flywheel, it would make the vehicle extremely fuel efficient, while emissions would be reduced to almost zero. If this sounds far-fetched, let me state that it has already been done. The flywheels used in the kinetic energy recovery system (KERS) in the 2009 Formula 1 racing season weigh just 5 kg and are brought up to a rotational speed of 64,000 rpm in just a few seconds (i.e., the time it takes to brake the car for a pit stop). Yet in this small amount of time the flywheel attains an energy of 480 KJ, which is enough energy to run a 1 kW hot plate, two overhead fans, a TV, several 100 watt light bulbs (i.e., a total of 5 kW), for one and a half minutes (96 seconds)!

Now, an engine has been invented that claims pure rotary output. This engine is extremely light and much more powerful than a similar-sized internal combustion piston engine. If this system were introduced it would make it possible to get all the power, acceleration and comfort of a conventional internal combustion piston engine, while using only a fraction of the fuel.

Such a system could also be used for home power generation, making it possible for each household to generate the electrical power that it uses. The figures are right, even the amount of energy produced by the `gyrobus', about 6.2 MJ is equivalent to about 1.8 KWh. If an ordinary household uses about 10 KWh (10 units) in one day it would mean that the flywheel would have to be charged just five times during each day to produce that amount of electricity. Of course there is wind age (frictional losses in the flywheel due to friction from the wind and ball bearings) but this amounts to just 100 W per hour and would be comparatively insignificant. A stationary flywheel system could produce a lot more energy than one used in a moving vehicle. There is no doubt that the idea of using a renewable source like the flywheel has a lot of potential and that it is something that should be looked into in the near future.

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