As competition increases for dwindling reserves of natural fossils fuels, many industrialized nations have for many years now been investigating alternative sources of generating greener, renewable energy. The demands of the emerging industrialized economies of Asia have placed even greater strain on the world’s diminishing stocks of fossil fuels and three principle means of generating renewable energy have emerged to counter the growing demand: solar, wind and hydro. Each tries to harness a basic element of nature, in the case of solar the sun, for wind power changing atmospheric conditions that lead to winds, and hydro relies on the movement of large volumes of water, most often dammed rivers but also harnessing the power of tidal waters.
The choice of which renewable energy resource an individual nation should invest in depends on many factors, but the choice is principally driven by the nation’s geography and climate. Secondary factors may include cost, efficiency, resource and expertise availability, and the level of the nation’s current commitment to renewable energy.
First, let us look at wind power. Generating power from wind requires turbines which are made to move by incident air movements. These are coupled to generators which produce electricity and feed it in to storage, or directly in to the grid system. Usually, generating larger quantities of power requires larger turbines, and often large farms of turbines, which, optimally, should be situated distant from each other. Additionally, they should be placed on towers and on higher ground where they are exposed to larger and more frequent air movements. Individual turbines can be noisy although improving technology and design is leading to reduced noise and space requirements.
As an island, the weather of the United Kingdom is well-suited to both wind power and tidal power. The United Kingdom is a significant investor in, and user of, wind turbines. Geographically positioned far beyond the sub-tropics, the climate and peak sunlight hours of the UK prohibit widespread year-round industrial use of solar technology. Wind features as a significant proportion of its commitment to produce 15% of its energy from renewable sources by the year 2020. In order to alleviate the potential blight on the landscape of large industrial wind farms in a nation of relatively limited available space, the UK has plans to build several large offshore wind farms. Offshore wind farms are generally more powerful than their onshore counterparts since turbines are exposed to the full force of cooling air currents. By 2015, 9GW offshore farms will begin delivering energy to the UK national grid. Such farms could have significant long-term benefits on the UK economy, potentially transforming the country from a net importer of energy to an net exporter, not to mention the potential for global knowledge and service sales.
Countries situated between the sub-tropics with significant coastlines may also make solar power an option for renewable energy. Solar power is derived from solar radiation falling upon chemical cells which react to produce a potential difference in the cell. This is the principle behind so-called active solar. Photovoltaic cells capture sunlight and the resultant electricity is stored in batteries to be used later or offloaded in to the grid. Clearly, solar power is best suited to locations with long periods of unbroken exposure to the sun. Solar can be used in areas of fewer sunlight hours, and where the sunlight is less intense. However, in order to create the equivalent power, it requires a greater area of PV cells and therefore more physical space and cost.
Unlike wind and hydro power generation, solar power generation in any given location is governed by the natural day night cycle. Solar has great potential for countries between the sub-tropics where hot cloudless days are often the norm. Many African nations whose economies and livelihoods have for decades fallen foul of the intense heat and searing sun of the equatorial may, with the use of solar, finally be able to generate sufficient power to join the slow, steady march on the way to industrialization; in the not too distant future, the potential of solar power offers the nations the opportunity to become leading exporters of electricity to the larger economies of Europe.
Passive solar is less appealing to industrial markets as it does not generate large quantities of power, relying more on the heating of materials of favourable thermal mass then re-channelling the heat through air flow.
Modern use of water to generate electricity is an extension of an age-old method. Previously, chaneling water to drop over wheels was used to drive mills and other basic machinery. Due to its roots, hydro is currently the best known and most widely used form of renewable energy production, accounting for about 20% of present global energy production. Furthermore, the basic ingredient, water, is readily available and the process used to create power does not expend the ‘fuel’.
Large scale power generation from hydro entails damning rivers or reservoirs. Often, this is only feasible in countries whose geographical features permit this. The world’s largest hydroelectric plants are in Brazil, Canada, Russia and China. China are responding to their increased need for power by building the world’s largest dam, the Three Gorges Dam, on the Yangtze River. Countries without such an abundance of hydroelectricity usually use it to provide additional power during peak demand periods.
For the small-scale user, micro-hydro energy production is possible by using small flowing streams, or re-using areas where ancient mills once stood on riverbanks. The United States is increasing its support for micro-hydro projects and several remote communities in the United Kingdom already utilize micro-hydro.
Compared with solar and wind power production, hydro is bay far the most predictable as it relies on human-governable constraints. However, there are certain drawbacks. Often, the aquatic ecosystem surrounding hydroelectric plants is disturbed or destroyed. Similarly, the displacement of the surrounding population can be significant; it is estimated that up to 1.3 million people have been effected by the construction of the Three Gorges Dam in China, in addition to flooding numerous cultural sites.
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