Energy

Pollution, Carbon Emission & Global Warming

The Burning Question & the Cool Answer

(Some thoughts by Derek Hartopp)

(This was written a few years ago, and explores the possibilities of regenerative braking, the heat pump, ambient energy, and other ways to use energy more efficiently)

As we face the reality of worsening air quality, and already disastrous climate changes, can we continue to effectively do nothing about controlling demands on burning fuel for energy? The so called "renewable" sources of energy, such as the sun, wind or tide, are unpredictable, and may not be there when we want them.

The politicians' solution of high tax on fuel, and reduced lifestyle, is not popular with the voters. Perhaps there could be a "third way", by using present energy sources much more efficiently, and without the dreaded accompanying loss of lifestyle. The following shows how we might keep present levels of activity, but with only about half the energy consumption!

TRANSPORT

Transport could be today's biggest polluter. Take the familiar motor car. We start our journey by accelerating through the gears to reach a comfortable cruising speed, and then, at the first red traffic light, we have to stop. The whole of the energy used to set the car in motion is wasted in heating up the brakes, and we have to start all over again.

REGENERATIVE BRAKING

If the car were powered by an electric motor, a considerable amount of this wasted energy could be returned to the battery, to help the next burst of acceleration. The principle is not new. In earlier days, a tram or trolleybus could check its speed going down a hill, by generating current to help the one coming up.

Compared with a petrol or diesel engine, an electric motor is the ideal power source for a road vehicle. Of the two basic kinds, one automatically increases its thrust when slowed down under load, while the other tends to maintain a constant speed with varying load. In the latter case, this means that a car would try to keep a steady speed, taking current from the battery when going uphill, and returning it when going down. Both qualities can be built into a single motor, and combined with electronic control. The big advantages of an electric motor are: First, its function is reversible. It can act as a brake, generating current which is returned to the battery. Second, it can cope with varying speeds and loads, In a way that needs no gears. And third, it produces a starting thrust while standing still, so needing no clutch. Anyone who has ridden on trolleybuses, will remember the smooth and rapid acceleration of these vehicles, along with the lack of noise, vibration and fumes.

THE "HYBRID" CAR

The major snag with today's electric car, is the size, weight and cost of the battery needed for sufficient cruising range on one charge. There is also the valid point, that the electricity to charge the battery has to be generated by burning fuel at the power stations, which still causes air pollution.

Here now is what might be considered as a compromise or "hybrid" solution toward producing a "green" car. The battery is of sufficient size to supply the motor's short-term needs of high current for acceleration and hill climbing. A comparatively<>small engine runs continually, driving a generator to keep the battery charge "topped up". This engine needs only to supply the average power for the journey. The "peaks" are met by the battery. Current is returned to the battery when descending hills or slowing down. The generator can also be the engine's starter-motor.

This basic idea can be taken much further. We have already eliminated the gearbox and clutch. By replacing the single electric motor by a smaller one built into each wheel, we can also lose the prop shaft and differential! "Four wheel drive" is normal, and slipping of any wheel need not take power from another. "Anti-lock" or "anti-spin" may also be standard features. With the motors used as brakes, there will be less wear on the ordinary friction brakes, now used only for emergencies or complete stops. In traffic jams, the engine can be switched off, to crawl several miles on reserve battery power alone, without pollution. Under normal charging conditions, the engine should be giving its best and cleanest performance.

The system will have some disadvantages. Top speeds are bound to be less than those of a typical high performance car, and the "vroom-vroom" will have been taken out of motoring for its keenest enthusiasts. For the rest, the ease and smoothness of control should have wide appeal, as also should the easy maintenance using plug-in units. Perhaps road safety might improve.

HOME HEATING

Yes, we have become aware of insulation, double glazing, and low energy light bulbs. But with the imposition of VAT on domestic fuel, we must look much further.

First, I would like to discuss some very fundamental things about heat itself. Except at a temperature of absolute zero (the coldest anything can possibly be), everything contains heat energy, even if it seems cold. Heat generally flows from hot things to cold ones until they all have the same temperature. But this is not always true.

Everyone that has blown up a cycle tyre, knows that the lower end of he pump gets hot. As the air in the pump is compressed (or concentrated), the heat energy it contains is concentrated too, causing a rise in temperature to make it feel hot. Conversely, when air is let out of a tyre, it expands, taking heat from its surroundings, and so feeling cold. In a rather more complicated way, this is the principle of the refrigerator.

THE "HEAT PUMP"

Most people will have noticed, that as the inside of the refrigerator is cooled, some tubes at the back become warm. Heat is taken from the inside to the outside.

Let us now imagine this process scaled up, and rearranged in reverse, so that the tubes at the back become a convector heater in our lounge, with the interior cooling element placed out of doors. (In practice, it may be buried in the ground for greater effect). Even in the depths of winter, heat can be taken from the cold air (or ground) outside, making it even colder, and brought indoors to keep us warm. "So what?", you may ask, "What is wrong with ordinary heaters?". Well, here is the crunch. An electric fire or convector heater, taking one kilowatt of power from the mains, delivers one kilowatt of heat into the room. A heat pump taking one kilowatt from the mains, can deliver something like three kilowatts of heat. A seemingly impossible three hundred percent efficiency, until it is realised that the extra two kilowatts come from the cold air outside.

The cost of electricity for heating can be cut by two thirds! Why has the idea not been exploited? The technology has been around as long as the refrigerator. Why has it been kept "on ice" for so long. Could it be that capital and maintenance costs are too high to make it economic? Or is it likely that its widespread use would be in conflict with other interests? One thing is certain. With the cost of electric heating cut by two thirds, no pensioner need ever again die from hypothermia.

THE FUTURE

We have just looked at two major ways of energy saving with present technology. I believe that just round the corner a whole new science is waiting, to give us unlimited energy for what I hope will be peaceful use.

It has already been shown that heat energy is present in relatively cold materials. Take air for example. Even on a cold day with no wind, its tiny invisible particles, or molecules, are dashing around at high speed in all directions and continually colliding. The warmer the air, the faster they move. Only at absolute zero temperature, would they stop. While they are moving, the molecules contain stored energy in the same way as a moving car or bullet. A collision involving either of the latter results in a spectacular release of energy, while the molecules just bounce off one another like perfect rubber balls.

<>The energy of things in motion is known as "kinetic energy" (from the same root as "kinematograph"). What has been described, is often called the "kinetic theory of heat". Several things confirm the theory. Here are just two. Very small things examined under a microscope can appear to be vibrating due to bombardment by molecules. In a room of perfectly still air, a bottle of perfume uncorked in one corner can almost immediately be scented in the opposite one, due to the quick diffusion of fast moving air and perfume molecules. Now, if we could somehow direct randomly moving and colliding air molecules into some kind of ordered movement, would it not be possible to make this kinetic energy do some useful work?

"AMBIENT ENERGY"

As a child, I used to like reading about perpetual motion machines, and proving how they could not work. The laws of "conservation of energy" tell us that we cannot get more out of a machine than we put in. But what I am about to describe would direct or concentrate the energy all around us in a way that it could be used.

I believe the science to make this possible will be complex and initially expensive, and so I will not attempt to discuss details here. But with a little exercise of the imagination, I would like to show the possibility. Think of a layer of material that would allow air molecules to pass through it only one way (or one way more easily than the other). This would cause a greater pressure on one side than the other, so making it want to move. It could be the basis of an ascending parachute, or a jet propulsion unit needing no fuel. With no smoke or fumes, it would just leave behind a trail of cold air to quickly disperse. The manufacturers' dream of cheap personal world-wide transport for all, could be realised far beyond any vision of Henry Ford.
But there has to be a black side to all this. A missile needing no propellant fuel would have unlimited range, which may not be in the best interest of world peace.

By the way, does anyone remember the drinking ducks, Dippy and Dally, a toy popular in the fifties? They kept moving by absorbing heat from the air by the evaporation of water from their beaks.

FURTHER POSSIBILITIES

Already with us is the science of "Thermo-electronics". There is now on sale a small refrigerator using this principle, that runs from a car battery. But that is not all. By simply reversing the direction of the current, the refrigerator is turned into a hot cupboard. Imagine this on a larger scale for heating or cooling a building, as a silent alternative to the heat pump.

In the future, there might be a new kind of battery charger. Most things draw current when connected to a battery, and by their "resistance", turn it into another form of energy such as heat. Could there be something with "negative resistance", that would make current flow back into the battery, by turning cold and taking heat from its surroundings? Could it replace the engine for charging the battery in the low-energy car described earlier?

As said before, a problem with electric power is its storage. Batteries are big, heavy and expensive. This can make it uneconomical to get a steady supply of electricity from a fluctuating energy source like a windmill. But let us suppose that technology could give us a better storage device in the form of a "super capacitor"? It is the "capacitor" in a camera flashgun, that stores electricity over a period of seconds, and then releases it (quite literally) in a flash. With its capacity improved by about a million times, such a device could usefully store electricity for household, industrial or transport purposes. There is just one snag. Placing a screwdriver across the terminals of an ordinary capacitor can produce quite a spark. (Don't do it! You could get a nasty shock or ruin the capacitor.) The same treatment of a super capacitor could produce a destructive and lethal explosion!

EFFICIENT ELECTRICITY?

When electricity is generated by the burning of fuel, only about one third of the released energy is actually turned into electricity. The remaining two thirds are completely wasted, as heat through the power station's cooling towers and chimneys. Coastal power stations may throw away this energy by heating up the sea. This is the main reason that electricity is normally expensive for heating, compared with other sources. By generating electricity where it is to be used, in the home or factory, the excess heat energy could be used for central heating and hot water. Is it not possible for boiler manufacturers and fuel companies to use some enterprise in developing such a system, to replace conventional central heating? Modern heat storage, with electronic control, could be devised to match the varying demands for heat and electrical energy. Even if not perfect, it would be better than throwing away a full two thirds of the energy produced.

<>TO CONCLUDE

Most of the ideas discussed here are part of present technology. If the speculation on future developments seems wild, I would suggest just looking at the last fifty years of technical progress. However, some things are certain. We do not have to burn fuel at the present rate to supply our energy needs. We can stop wasting the energy we have, and use sources that do not involve burning fuel. With cheaper home heating, there need be no more hypothermia deaths. There has to be a more rational approach to transport. Railways, with the lowest rolling friction and air resistance, use the least energy, and are adaptable to regenerative braking. They also have the best safety record. Yet for political reasons, they are being systematically destroyed, as road chaos mounts. Are all journeys really necessary? How much time-wasting commuter travel could have been avoided by better town planning? Or lorry journeys saved by the better siting of factories, and less fragmented production? Shall we have learnt our lesson too late, after fuel supplies have run out, or the air has become totally unbreathable?