Everybody knows one must go to the service station to fill one’s tank with gasoline, and that the service station is refilled by trucks coming from the refinery. The refinery itself is fed with crude oil coming by tankers from oil producing countries faraway: oil is an energy source but gasoline is a manufactured energy vector. It is so easy to plug in the electrical outlet on the wall that one forgets electricity too must be manufactured from diverse primary sources, and then transported and distributed to our sockets: electricity is not an energy source either, it is an energy vector, and very handy as they come!
In 2007, more than 1.5 billion people on Earth have no access to any electrical grid. Without light bulbs, it is difficult to do one’s homework after school. Without a fridge, one can hardly keep vaccines and remedies, not to mention fresh food. No wonder therefore that there is a correlation between a minimum access to electricity and public health, literacy, and so on. Every year, the United Nations Development Program UNDP publishes, country by country, a Human Development Index HDI, which mixes statistics about human health (life expectancy, child mortality), education and national wealth.
The figure above shows that beneath a minimum level of per capita electricity consumption, there is simply no development. Conversely, above a given level, the correlation vanishes: it is the "comfort" area (where Europe happily lies) or even the “waste” area.
It's no accident either that electricity accounts for an increasingly large share of energy consumption in all developed countries, and that different forecasts confirm this trend (see below):
Initially, electricity was mainly used for lighting, then to power motors. Then appeared the electro-chemical uses (electrolysis, fabrication of chlorine, soda, aluminium, etc.): by the end of World War II, lighting, motors and electrolysis accounted for the quasi-totality of the electrical consumption. Since then, electricity uses have widely diversified with, notably, appliances, electronics, computers and communications.
Compared with other forms of energy, electricity offers a number of specific and often unique advantages:
1. Electricity is the means through which other forms of energy can be converted from one to the other. Who could imagine converting mechanical energy into chemical energy or light without electricity?
2. Substituting electricity for other forms of primary energy often leads to a significant improvement in performance and, therefore, in the overall energy efficiency of processes.
3. By using electricity, motors and controls can be decentralized, thus offering the average citizen a multitude of mechanical and electronic slaves that would make a Roman patrician green with envy!
4. Except in the case of heating, the use of renewable energies almost always involves an electrical "vector" (production, transportation and distribution).
5. Electricity is the preferred, if not only, vector for information and communications (even the photons traveling along an optical fiber are produced and modulated by electrons).
6. Electricity is a clean form of energy in the transportation, distribution and end-use phases – no pollution, no greenhouse gas emissions except ozone. It is also clean in the production phase if generated by nuclear, hydraulic, solar or wind sources.
On the down side of this list of advantages, electricity presents one considerable drawback: it is virtually impossible to store, except in very small quantities and at a high cost in electric batteries. It can be stored indirectly (e.g. pumping stations, flywheels), though this remains relatively rare. Electricity must be produced to meet immediate demand at any time – the perfect example of "just-in-time" methods!
This explains why it still plays such a small role in road transport, despite the fact that the first motor vehicle to reach a speed of 100 km/h was an electric car (Jenatzy's "Jamais Contente" in 1899). Storage batteries do not offer the same range as a gas tank and take a lot longer to fill.
Another problem raised by these storage difficulties is that if a network is powered by an intermittent and random source, a source of equal capacity must be standing by, ready to take over as soon as it is needed.
To complete the picture, one can mention two additional properties which are difficult to classify as quality or defect:
1. It is easy to track the origin of the coal or the crude oil which one uses. In contrast, when they travel through the wires, electrons loose their identity card. It is impossible to follow one electron from the producer to the consumer… Once connected to the grid, and even if he pays the company an overcharge to be supplied with "green electricity", even the fiercest Greenpeace activist cannot bar nuclear electricity from entering his home.
2. Electricity blackouts are almost unacceptable for the disruption they cause in the modern societies. Sometimes, their consequences may be dramatic (emergency rooms in hospitals, for instance). In France, strikes are carried out almost without electricity cuts, and EDF can hardly disconnect anybody, even if he does not pay his bill.
TWh = Billion kWh
Worldwide, coal is by far the largest source of electricity. In France, it is nuclear power. In both cases, the share of non-hydro renewable energy sources is still relatively small, though growing fast.