Why renewable energy is important for sustainable development
Introduction
The term 'renewable energy' is used to refer to a range of distinct technologies that are designed to harness different energy sources available from the planetary environment rather than extracted from fossil fuels. As was explained in 'Understanding the real economy', solar radiation and gravity are two major sources of such energy but the energy released into the environment by mankind's use of fossil fuels is another and capturing it is an important way of recognising and correcting the mistake made in our past inefficient and unsustainable use of these important capital resources. Using a diversity of both source and technology is the difference between renewable energy and sustainable energy. Having a sustainable energy supply is a vital component of sustainable development.
Harnessing freed energy
As I write this the wind is gusting fiercely outside, a consequence, according to some experts, of the energy we have released as a result of using of fossil fuels to power human economic development. The water in the oceans is in the process of expanding, as a result of the additional heat, and the effects are exaggerated by previously frozen water running off the land. Together, the stronger wind and increased ocean volume lead to bigger waves and higher tides. But this does provide opportunities, especially for an island nation with a long coastline and a national electricity grid because the probability is that the wind is blowing and waves breaking somewhere with sufficient strength to be worth harnessing.
|
|
Wind and wave power
being harnessed on Orkney - source Herriot Watt University |
A more sustainable use of solar radiation
All experts would agree that the wind and waves are, ultimately, powered by energy from the sun and the tides driven by gravitational interaction between the Earth and the Moon. Fossil fuels are a store of 'ancient sunlight' (a concept popularised and expanded on by Thom Hartmann). However, technology for tapping the solar radiation revenue (i.e. that energy we are currently receiving) has been developed in ways that are appropriate to our present usage and requirements. Photovoltaic cells convert sunlight into electricity, whilst modern architecture seeks to use the heat from the sun more efficiently than has generally been achieved in the past by using passive solar designs.
|
|
(Left) Photovoltaic roof in |
In Britain it is now possible for users of photovoltaic panels to be connected to the national electricity grid so that excess power generated can be exported and sold, whilst power can be bought-in when the panels are not operating or providing sufficient power for immediate use (Diagram (right) supplied by Solar Century).
Using gravity - mature technology for renewable energy
Wheels and later turbines have been used to harness power from moving water for centuries and the source of this energy is gravity. Dams and tidal barrages also use gravity to provide the potential to drive turbines to generate electricity. There are however two types of gravity involved: the Earth's own, which is the power for rivers and dams, and that from the interaction of our planet and the Moon, which causes tides (although water volume and wind strength also affect the power available from tides).
|
|
The diagram (left) illustrates the principle of
how a turbine works. In this case, with the outgoing tide providing a
differential between river level and sea, the effect is similar to that used by
a dam higher up the river course.
However, by using tidal power, the turbine will also be driven by the
waters going in the opposite direction when the tide comes in. (Left below) is a picture of a barrage
in operation. |
|
|
Storing energy sustainably
Fossil fuels are an energy store and their use has offered mankind a potential for powered transport that has revolutionised our lives because of the speeds and distances that can be achieved. Plants can store sunlight in the relatively short-term but, when converted into biomass (illustrated by picture to right), have a potential to substitute for fossil fuels in static heat or power production.
In fact, all the various renewable energy technologies described
above can, when used in conjunction with one another, meet all of our static
power and heat requirements, including electric railway trains and trams that
take their power from the track or overhead power lines (such as trams
operating in Sheffield - right).
Otherwise, they have limited application for transportation. For example, prototype wheeled vehicles driven by photovoltaic cells have been constructed and even a propeller driven aeroplane but they do require sunlight to be reaching the cells to maintain power. Batteries have been used for over a hundred years to store electricity and are used for transport applications but even the latest technology cannot match the power to weight ratio achieved by using oil derivatives to fuel conventional engines.
However, an alternative concept that is the subject of current research is the use of electricity from renewable technologies to separate the hydrogen and oxygen contained in water to provide the store of potential energy and then to recombine them for both static and moving applications.
Fuel cells (illustrated right) are one promising technology of this type that could replace conventional batteries. Whereas current batteries incorporate toxic chemicals, such as acids, that require reprocessing once they have been used, fuel cells produce water as a bye-product.
Alternatively hydrogen and oxygen can be burnt together, in the same way as hydrocarbons (such as petrol) and oxygen are currently to produce heat and power from piston or turbine engines. The important difference is that the exhaust would be mostly water vapour and far less polluting than the gasses that are produced by all engines using fossil fuels. Unfortunately, hydrogen is even more explosive and therefore more difficult to store than our present fuels.
Conclusion
There is a need, therefore, for innovative ideas about storing portable energy to provide power for transport or for a rethink of our current requirements for mobility, if we are to have sustainable energy, which is essential to achieve sustainable development.
January 03
Front Page | Home Page for individuals | Business Services Index | Site contents & internal links | Email the Author