Nowadays,when a great progress of civilization is taking place, energy is the key to sustainable development.It has always been indispensable to most human activities such as domestic life, agriculture, industry and transport.Now it is a precious good but today’s energy system is dominated by the powerful and centralized supply of fossil fuels.80% of them are consumed in industrialized countries and they account for 80% of carbon emissions-the main cause of the greenhouse effect.World population is expected to double by 2050 and the result will be that energy consumption will triple by the middle of the 21st century.One can imagine the level of environmental pollution resulting from several decades of demographic growth.The amount of needed energy will probably increase thanks to the development of technology and new equipment.
We can help to change the course of events.First,the consumption of energyshould be saved and secondly,more flexible fuels(renewable energies)should be used.The new sources of energy are sun, wind. water, modern biomass(wood harvested in such waysas to avoid alterinf the forests).The development of these new sources offers a better access to energy service.
Solar-thermal technologies that use mirrors or lenses to concentrate the sun’s rays on the heatexchanger,are being incorporated in power plant projects in many countries in the worldElectricity is also produced by photovoltaic devices.They create no pollution and can be opetated almost anywhereand require little maintenance.This technology works economically and is not connected to national power plants.
Biomass is another major alternative energy source.Burning of wood and straw gives biomass energy which is already used largely for cooking and heating in developing countries.But this way of gaining energy brings a lot of problems.eg.land degradation,deforestation.