The Big Picture: Uses & Sources of Renewable Energy

Structure of Global EnergyToday, most of the energy the world uses, does not stem from renewable sources. In fact, only 18% of the world's final energy consumption comes from renewables. The majority is divided up by fossil fuels (79%) and nuclear energy (3%).

Of the renewables, biomass is by far (78%) the most prominent source, mostly used for heat, followed by hydro energy (18%). So-called "new" sources including wind and solar account for around 1% of world's renewable energy use.

However, the picture looks very different when considering electricity generation. About one fifth of the world's energy is consumed in the form of electricity. Here, the share of renewables is slightly higher (18.1%). However, the mix of renewables is very different. 88% of electricity from renewables comes from hydro - i.e. rivers and dams, followed by biomass (6%) and others (6%).

Although their contribution looks miniscule, the new technologies will have a major role to play. This is because demand for electricity rises more sharply than overall demand. Hydro, which is currently the main renewable source for electricity will not be able to keep up the pace, as suitable locations become scarce, making way for wind, solar, wave and tidal.

Final Energy Consumption denotes the amount of energy actually consumed (after conversion losses) by households, industry, agriculture and transport.

 

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Saving Fossil Energy

The single most salient benefit of renewable energy sources is the saving of fossil sources, and consequently fewer green house gas emissions and less reliance on diminishing resources.

We are principally consuming energy in the form of heat, electricity (which can be further converted) or by burning fuels in transport. By converting primary energy into energy we can consume, most conversion processes require energy from fossil sources, taking into account that it requires energy to build power plants, not just to run them.

Clean energy technologies provide savings of fossil energy, as they need less energy from fossil sources than they provide over their lifetime.

Electricity Generation

Electricity generation is dominated by coal-fired power stations, that need 2.9kWh of primary fossil energy for every kWh of electricity generated. I.e. they provide a net loss of 1.9kWh of fossil energy for every 1kWh electricity. Conversely, renewable energies provide a net saving of fossil energy. Hydro, for instance, uses only 0.01kWh of fossil energy per kWh of electricity!

Heat Generation

With heat generation, the method that uses most fossil energy is electricity. This is because of losses incurred by converting heat from fossil sources into electricity. The exact value for heat from electricity depends on the energy mix of the country.

Comparing solar thermal technology with photovoltaics, it is striking that photovoltaics provide less fossil energy savings than solar thermal because of the high energy requirement in the production of crystalline silicon. Second generation photovoltaics have a more favourable energy pay-back time.

Transport

To compare different fules, the amount of primary fossil energy is divided by the usable energy that can be used. Surprisingly, plant oils offer the maximum savings of 0.9kWh per kWh against an average fossil fuel of petrol or diesel.

Overall, clean energy technologies can help reduce the use of fossil energy, thus reducing pollution, green house gas emissions and slowing down the depletion of finite resources.

 

LinksEU Energy Portal on data of renewable energy in the EU's 27 member states. The above figures are from 2007.
U.S. Energy Information Administration - International Energy Statistics for national electricity consumption figures.

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