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There is considerable confusion in the newspapers and in the mind of Mr. Basic Citizen about the types of energy, their virtues, hazards and shortcomings.

Facts, trends and reflections.

Steam locomotive
Oil tanks
Windmill farm
Oil field
Photovoltaic panel
Nuclear power
Solar panel

What are the perceived issues?

Some of the real questions are:

Here is a list of the main types of energy:

Here a table with their main characteristics:

Energy type CO2? Renewable? Applications Nuisance?
Fossil fuels
Coal Yes No Electricity Dust, acids, ash
Oil Yes No Electricity, vehicles Acids, ash
Gas (natural and LPG) Yes No Electricity, vehicles Acids
Wood Yes Yes Heating Dust, ash
Bagasse Yes Yes Electricity, heating Dust, ash
Ethanol Yes Yes Vehicles Energetical balance?
Rapeseed oil Yes Yes Vehicles, electricity Energetical balance?
Dams (mountain) No Almost Electricity Change biotope
Rivers No Almost Electricity Change biotope
Tide No Yes Electricity Little
Nuclear power
Nuclear stations No Almost Electricity Radiations, waste
Windmills No Yes Electricity Noise
Heaters No Yes Warm water
Voltaic cells No Yes Light Low power
Solar stations No Yes Electricity Low output
Fuel cells No More or less Vehicles Not ready

Too expensive?

Energy is cheap, at least for us in industrialised countries. We are used to get everything at the click of a button: heat, transportation, information, water. Our ancestors had to bring in wood logs to feed their fireplaces and ovens in winter, to maintain horses, donkeys or camels for transportation, to go to the deep well or to the river for water.

We are exploiting natural resources: oil, coal, uranium, water; we think that because they are natural, they are free of charge. Oil used to be very cheap until recently. It still is not expensive, as in Europe about 70% of the cost of petrol for your car is taxes.

Too little?

If you look at the world's reserves of oil, gas, coal and water, yes there is too little: your grand-children will have to use other sources of energy, as the oil and coal reserves will be depleted.

Besides, there are certainly better things to do with oil than just burn it. Use it as a feedstock for synthetic chemicals, for instance.

How much really?

Look at this: the world has consumed 17'080 TWh (terawatthours, or 17.1×1012 Wh) of electricity in 2007; in 2003, the figure was 15'800 TWh. Out of this, the USA have consumed 3924 TWh in 2007, which is 23% of the total, but flat from 2003. Remember that the USA population is only 4.5% of the world's population. The picture on the right shows the consumption of the top ten countries. And here, a table with the 30 biggest electricity consumers and 5 of the smallest for the years 1998, 2003, and 2007.

You don't understand the TWh unit? Simple: a 100 Watt bulb consumes 100 Wh, or 0.1 kWh, in one hour. If you leave it on all year, which is 8760 hours, your bulb will consume 876 kWh in this year. So the world's electricity consumption of 17080 TWh is like 20 billions of bulbs left on all year round, or (only) about 3 bulbs (300 W or 0.3 kW of power) per living person. Details about the units below.

The second graph shows the oil consumption, expressed in barrels per capita, of twenty rich and poor conuntries. The citizen of the USA consumes twice the amount of oil of a French person, and 30 times more than an Indian. Let's look closer at the example of France: 12.7 barrels per person at 159 L per barrel is a total of 2019 litres per year. Assuming the Frenchman has a car and drives 20'000 km per year, and the car runs 10 km per litre of petrol, this man will burn 2000 L of petrol in a year (and spend 2600 €). Now you are telling me: why, all Frenchmen do not drive 20'000 km per year, and infants don't have cars, and mine runs more than 10 km per litre. All right, but the oil is also used to heat your house, to fly aeroplanes and to produce some chemicals.

Power consumption 2007
Oil consumption 2003

Problems of scale

You can produce energy for a house, a villa or a farm in small scale, using solar, wind and hydraulic energy. For large cities you need a central source of energy, a power station. Solar energy can be used additionally, and small towns can be fed with windmill parks.

Saving energy

In the future, we will learn how to save energy, through better insulation, and also just by turning the heating two degrees cooler in winter time and the air condition two degrees warmer in summer. In France and many other countries of Western Europe, air conditioning is not necessary in private houses and apartments. It is criminal to try and sell aircon systems that will be used less than six weeks in a year and really nice to have for an average of 10 days per year.

Environmentally harmful?

Yes, all types of energy are harming the environment to some extent, but there are huge differences:


Yes, by nature energy is potentially dangerous. Coal mines kill many workers, oil spills kill fish and pollute water, nuclear power stations can blow up and destroy life hundreds of miles around.

Let's now examine the different types of energy a little closer.

Fossil fuels

I mean coal, oil and gas. All three are natural resources. All three will be exhausted within a short time, say 50 to 200 years, which is short indeed if you realise that these three fuels were produced by anture from organic substances like leaves and peat, and it took millions of years to transform the original matter into oil and coal.

Burning oil, coal or gas produces carbon dioxide, deemed to contribute to global warming. If the fuel is not pure, you also produce harmful by-products, such as sulphur dioxide (remember the "acid rains" ever present in the 1970's and 80's, now under control through treatment of the combustion fumes), nitrous oxides (very toxic, but also under control in developed countries), and different sorts of harmful ashes, particularly when they contain heavy metals.

These fossil fuels are used to produce electricity, but also to power your car. Electricity can be produced by other means (nuclear, solar, wind energy) but your car relies today exclusively on petrol or diesel fuel. If it burns natural gas or LPG, it is slightly less polluting, but only slightly.

So-called "hybrid" cars are also a little better, because they burn fuel more efficiently: in slow traffic, when combustion engines have notoriously bad efficiency, the hybrid car uses electricity produced by the engine when it can operate in good conditions, and stored in batteries. Heavy solution, but not as polluting as normal cars.

Today, there is no immediate alternative to fossil fuels for vehicles. Tomorrow, there may be fuel cells (see below). Today, you can move an aircraft carrier with an atomic engine, but not your car or my motorbike.

In 2015, electric cars begin to reach commercial scale. They don't pollute the air directly, but how environment-friendly is the process used to produce the electricity they consume?

Biodiesel sample


At first sight, burning vegetable oil, ethanol or methanol (both being alcohols) in your car or in a power station does nothing to pollution: it creates just as much CO2 as other fuels. It only preserves natural resources, as these man-made fuels are renewable. Esterified vegetable oils are called "biodiesel". They can be used in mixture with fossil diesel, or pure in specially adapted engines.

The promoters of biodiesel and bio-ethanol however have an interesting argument: the growth of rapeseed or sugar cane or beet consumes carbon from the CO2 available in the atmosphere. This is naturally valid for any plant: it grows through photosynthesis, which converts CO2 into organic molecules. In other words, expanding arable land and protecting forests (instead of covering land with concrete and allowing deserts to replace cultures) would contribute effectively in the balance of CO2. According to the promoters of bio-diesel, the net emission is only 25% of that produced by fossil fuels.

Bio-ethanol is simply ethyl alcohol produced by fermentation from a feedstock rich in sugar. Its energy yield is lower than that of biodiesel. However, as long as it is based on existing waste, it is not a bad idea. It is being used already in certain countries, notably in Brazil.

Creating this bio-fuel on a very large scale is also a serious challenge, as huge agricultural space would be necessary, with corresponding problems of fertilisers, watering and possibly pest control.

The same applies to wood and other vegetal combustible matter.

Some analysts say that the net energetical balance of many biofuels is negative, meaning the energy consumed to produce and transport them is greater than the energy produced.

Cost of bio-ethanol, according to a Brazilian magazine (Jan 2006):

Brazil 0.23 US$/L(sugar cane)
USA0.31 US$/L(maize)
France0.50 US$/L(sugar beet)

At 63 US$ per barrel in 2006 (159 litres), oil costs 0.40 US$/L. At 110 US$ in March 2008, it costs almost 0.70 $. Brazil has been producing, for over 30 years, a large volume of alcohol used as car fuel.

Biodiesel can also be produced from used cooking oil and recycled engine oil. This at least would be a useful industry, but at present only a few municipalities in Japan have started recycling cooking oil.

The whole subject of bio-energy is very political and controversial. See my blog of September 2007. Many people talk about it without knowing well the subject, just to "look green"... I recommend the well documented Wikipedia article about bio-diesel.

Hydraulic energy

You can use it only to produce electricity, not to power your car. In many countries, the hydraulic resources are already exploited, and there is not much room for more. Also, it creates big changes in geographical environment, often with secondary problems related to the disappearance of towns and villages and to natural irrigation.

Similarly, electricity produced by the energy of tides has limited application, because tide-powered stations can be installed only in very specific places (estuaries).

Nuclear power

You can use it only to produce electricity, not for your car, unless it has only an electric motor. Today, I really don't see small scale nuclear aplications.

On 1st October 2005, 442 reactors were in operation worldwide. See the map. 16% of the world's electricity is generated by nuclear power. In the USA, it is a modest 20 %. In South Korea, it is 38 %, in France, 78 %! To anyone wishing to turn off all nuclear plants in France, you should offer a container-load of candles and ask them how they will operate their computer, TV and dishwasher with the candles.

Nuclear power does not produce CO2 or other greenhouse gases. So it cannot change immediately our climate.

However, nuclear power plants produce radioactive waste, and today nobody knows, I repeat, nobody knows how to handle this waste so as to make it harmless. The radwaste is buried deep underground, and everybody hopes that it will not leak radioactivity. The problem is that this waste remains radioactive for a very long time, thousands of years for some of the radioactive species. A leakage of radioactivity into the atmosphere can have dramatic consequences, as we have seen in the Chernobyl accident that occurred in Ukraine in the Spring of 1986.

Nevertheless, I believe that nuclear energy will be further developed in the coming years, because it uses little natural resources, and could use none at all if the "fast breeder" reactor were built in a safe way. If the world's industry had invested as many dollars in research about how to make safe nuclear energy as it has done for oil and transportation, we would today have a fairly safe and sustainable source of energy for public distribution.

Wind energy

Wind is totally free of charge, but it does not blow all the time, which limits its use. Besides, windmill farms are somewhat noisy and have a definite impact on the landscape. But installed at some distance of the town, as I have seen in Jaisalmer in the desert of Eastern Rajahstan, it is the best solution to supply cheap power in an area without water and without other resources.

Several American and European companies have tried to sell aeolian turbines for individual houses. As of today, they failed. To have a decent efficiency, widmills must not only be installed in windy areas, but also high enough above the ground so as to avoid turbulences, which means you can't simply put them on your roof. Besides, it is not possible to store the electrical energy produced in your household.

Solar map

Solar energy

Click the small map on the right to enlarge it.

Using the sun to produce large quantities of power (many MW, as required by villages or towns) does not seem to be viable today. Similarly, sun-powered cars, each weighing 70 kg and running at 45 km/h under the Australian sun, are just gadgets. Solar energy is not strong enough to power your car, a commercial aeroplane or the French TGV.

However, the sun is absolutely suitable to heat your house in winter time and produce hot water for your shower and kitchen. In Switzerland, a country that is rather cold in winter, many houses are now built with elaborate insulation technologies and solar energy supply. In some countries (e.g. Israel) a majority of roofs have solar heaters. This example should really be followed.

Voltaic panels that convert light directly into electricity are very useful instead of batteries when the amount of energy required is small. In 2015, the Swiss aeroplane "Solar Impulse" was able to travel several thousand kilometers on solar energy alone. And similar panels can be installed in stations to recharge your electric car.

Fuel cells

For a very good description of fuel cells and all environmental and production issues, see Wikipedia in English or French. A fuel cell produces electricity in a way similar to a battery, but it consumes an external fuel. This process is not yet commercially available. Fuel cells produce electricity, some heat and water, no toxic or harmful waste. The process consumes hydrogen, which is not toxic, but not readily available and hazardous to produce. I have little information here and will complete this section progressively.

Units of power and energy

Power is measured in Watts. You know the power required to light a bulb (15 to 100 W) and to heat your oven (1200 to 2000 W). 1000 W is a kW (one kilowatt). Other units of power, such as horsepowers, are now obsolete. If you like the old unit, 1 HP is equal to 735 W.
One GW (gigawatt) is equal to one billion watts. G stands for 109.

Energy in this context is expressed in kWh (scientific writing would be kW·h). One kilowatthour is the consumption of one kilowatt (kW) of power during one hour. The official unit for energy is Joule (J) but it is very small, as 1 kWh is equal to 3 600 000 J.
One TWh (terawatt-hour) is equal to one billion kilowatt-hours, or thousand billion watt-hours. T stands for 1012.
Among non-metric units, you may find BTU (British Thermal Unit). 1 BTU = 1055 J = 0.293 Wh.

Total worldwide electrical energy consumption in 2004: 16250 TWh, of which 2620 TWh is nuclear energy.

Total nuclear power installed: about 375 GW. If you multiply by the number of hours in a year (8760), you get 3285 TWh, more than the nuclear share of 2620 TWh shown above. This is due to the fact that the stations do not operate constantly at full power: there are periods of low demand, and stations may be shut down for maintenance.

Remember that



Statistic data extracted principally from:

* Note : Since I started this page in 2006, several things have changed: windmill farms now cover vast areas on the sea or on land, hundreds of thousands of roofs are covered with photovoltaic panels, biofuels are no longer fashionable. In 2015, the price of an oil barrel went down from a maximum of 140 US$ to 50 or 60 $. I modified my text accordingly.

© François de Dardel

If you have clicked on the icon at the top, the music is the Coriolan overture by Ludwig van Beethoven (see my music page).

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