In this modern world most of us take energy for granted. It is something that has always been there for us to use and it is only when there is a sudden interruption in the supply that we realise the degree of our dependence. A failure of the domestic electricity supply or a sudden shortage of motor fuel becomes a major crises.

How different life is in other parts of the world. Many people in the developing world live in villages that lack electricity or the other trappings that we take for granted, so everything has to be done by hand. Homegrown grain must be ground using a pestle and mortar and then cooked on an open fire that probably takes up to two hours. This of course does not count the time taken to gather wood and since there is no electricity to run a pump, there is always a long walk to the nearest well to collect water.

Most of us who take our energy so much for granted never pause to thing how much we waste as we go about the most basic activities of our daily routine. We ignore the fact that energy is a scarce and valuable commodity. One day the forces of globalisation will bring energy to the remotest parts of the world, but energy capacity is far from limitless.

For so long energy usage has been such a basic element of human advancement that it is not at all surprising to see it acquiring mounting significance in this era of globalisation. It pervades every aspect of our lives, from the simplest of everyday tasks to the shaping of our immediate environment and it is having an increasing influence on the geopolitical calculations of all governments.

The projection is that by 2030 world energy consumption will have increased by 44% and 73% of that increase will be accrued within non-OECD (Organisation for Economic Co-operation and Development) countries like India and China. It has also been estimated that between 2007 and 2030 a total of $26 trillion will be invested in the energy sector, making it the biggest business in the world.

Energy in all its forms has fuelled the continuing integration of the nations of the world and their economies. The forces of globalisation have influenced and been influenced by higher energy consumption. This has raised the stakes involved in the formation of national energy policies and the operation of global energy markets. Demand for energy has risen as strong economic growth has brought with it the need to ship more goods and services around the world.

The vulnerability of this supply chain has been illustrated by recent increased costs of transport coupled with a declining level of supply in the short term. This has led to spikes in demand and higher prices to the consumer. This in turn has raised the cost of living, as energy costs have assumed a growing share of household spending.

With energy supply and demand being in a constant state of flux, it is impossible to accurately predict the exact size of future global energy demand, but all trends suggest that consumption will certainly keep pace with the growth of world population.

Energy issues will become more prominent as emerging economies such as those of India and China continue to modernise and industrialise, while developed countries place an ever-greater premium on securing energy assets and achieving energy independence.

Energy can be obtained from a number of different sources. Coal, petroleum and natural gas are known as fossil fuels and together they provide about 86% of the world's energy, with coal providing 26.6%, petroleum providing 36.8% and natural gas providing 22.9%.

Originally coal was the chief source of power and in the developing world this is often still the case. It is relatively cheap to obtain, but environmental pollution levels are high and it is usually highly dangerous to extract. Petroleum, commonly referred to as oil, is universally used for heating, in commercial activities and for transport. It is toxic to almost all forms of life.

Natural gas is often described as the cleanest of fossil fuels, but its extraction often requires a process that has a seriously detrimental effect on the environment. The burning of fossil fuels produces around 21.3 billion tonnes of carbon dioxide each year and although about half of this is absorbed as part of a natural world process, this still leads to a net increase of 10.65 billion tonnes into the atmosphere every year.

Carbon dioxide is one of the so-called greenhouse gases that effectively put a blanket around the world causing the average surface temperatures to rise, by preventing solar radiation from being reflected back into space.

Electricity is a very clean form of energy, but often the process of generating it brings a number of environmental concerns. Hydropower has been hailed a very clean and reliable and although the initial construction costs are high, once built a hydroelectric plant can run for many years. The downside is that it brings with it a number of serious issues.

The usual practice is to build a dam across a valley and then flood it. Not only does this result in the need to uproot all of the human inhabitants, but it will also completely destroy the habitats of the various other species of life that are living there.

Nuclear power has also been shown to be a very effective producer of electricity, but a problem with this method is the need for safe disposal of spent fuel rods that will remain radioactive for a considerable number of years. Basically there are two alternatives, one being to bury them and the other to reprocess them. Burying them is not environmentally very friendly and reprocessing them produces plutonium, which in the wrong hands could be used to produce very unpleasant weapons.

Additionally there have been several serious nuclear incidents in recent years, not the least being the one following the Japanese earthquake and tsunami in March 2011.

Solar power has been harnessed for many years in countries where there are long periods of sunshine each day. Older systems simply provided domestic hot water, but as technology has advanced photovoltaic cells have been developed that are capable of producing electricity even from moonlight. A problem is that they take up a lot of space if large amounts of electricity are to be generated and experiments are taking place where large panels are floated on the surfaces of industrial reservoirs. It has been estimated that in many countries solar power could provide 50% to 75% of all domestic hot water energy.

Wave and tidal power is another form of energy that can be used to generate electricity, with the first commercial wave farm being officially opened in Portugal in 2008. It has been estimated that wave energy around the British Isles has the capacity to meet three times the current UK electricity demand.

Biofuels are a very popular source of energy in some parts of the world. In this case plant material is processed to provide bioethanol as an alternative to conventional auto fuel. In Brazil bioethanol provides 18% of auto fuel, but large areas of land are needed to grow the plant material necessary for the production process and this has been at the expense of the Amazonian rainforest.

The Dutch traditionally harnessed the power of the wind to great effect in the 17th century and today wind can be used to power turbines to generate electricity. Wind power will never be able to replace conventional methods of generating electricity, but modern wind turbines consume no fuel and emit no air pollution and can provide a very useful and environmentally friendly top up.

Unfortunately these turbines only work when the wind blows and there has been some criticism of the tendency to group large numbers together to create wind farms that spoil the aesthetic appearance of the countryside. Concerns have also been raised about noise, danger to birds and bats and the possibility that the shadow flicker could be harmful to people suffering from epilepsy.

Wind power, solar energy, wave power and biofuels are all examples of sustainable energy. This is energy that meets the needs of the present, without compromising the needs of future generations. Sustainable energy sources generally include all renewable energy sources.

Researchers in the United States have produced a plan that could see all of the world's energy being obtained from sustainable sources by the year 2050.

They see a future world where all vehicles, ships and trains would be powered by electricity and hydrogen fuel cells. Aircraft would run on liquid hydrogen and houses would be warmed or cooled by electricity. Natural gas and coal would no longer be used and the sun would pre-heat all water.

Electricity and hydrogen would power all commercial premises and in all cases hydrogen would be produced from electricity. In other words the world would be powered by a combination of wind, water and the sun.

The researchers claim that the necessary technology already exists and if the plan was put in place it could be used to halt climate change, reduce air and water pollution, develop secure and reliable energy sources and save between 2.5 and 3 million lives each year. The costs, they claim, would be comparable to the current world spend on energy.

This is obviously a dream, since it would only work if society and the world's leaders came to a united agreement. In the meantime the best that we can do is to persuade people of the need to conserve energy. One of the best ways of persuading people to reduce their energy consumption is to make it financially worth their while. A simple way is to improve the insulation of homes to reduce heat loss, where the costs involved very rapidly pay for themselves.

Energy is precious - we can't manage without it, but we need to learn how to manage it wisely.