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Recent News on Energy and the Environment 02.01.09

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“Spatial Footprint” Challenges of Solar Energy Use

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Submitted by: Karl Ramjohn

Solar energy can be utilized in either passive or active systems. Passive systems do not contain any internal energy sources, and can be used for direct heating (e.g. solar dryers, water heaters, etc.) or day-time lighting (e.g. “green” office buildings). Photovoltaic devices are an example of active systems based on semiconductor technology, often using silicon (an indirect semiconductor).

The advantages of using solar radiation are well established and often cited – such as their ability (with proper design) to lower energy costs, reduce emissions and other environmental pollution, thereby initiating the process of competitively replacing hydrocarbon use, and thus contributing to sustainable development.

Solar energy approaches are also frequently suggested as a sustainable solution in less-developed countries in the tropical environment, on the assumption of having less seasonal variation in day-length and more hours of direct sunlight each day (i.e., usually a higher intensity and longer duration of incident solar radiation each day). The fuel medium (solar radiation) is also an “open-access” resource (no direct user cost). The overall decline in the operational costs seen over the past 35+ years is also typically acknowledged.

However, one major challenge remains with regard to conversion to solar energy use – their spatial footprint (land use requirement) in the event that larger scale utilization is proven feasible. In particular, for the use of flat-plate collectors or PV systems in tropical environments, this becomes an issue.

The primary reason is that to optimize the use of solar radiation, the panels (or plates) need to be sloped so as to correspond to the latitude of the specific area of the Earth, hence taking up more horizontal space in the tropics. If we take the example of an island in the middle-tropics such Trinidad & Tobago, implementation will require the slope of the panels to be 10 degrees (corresponding to latitude) for the same technology that may be placed at an angle of 40 degrees in countries within temperate regions. The implication is that the area set aside for power generation (or other solar energy use) will no longer be available for other land uses (such as agriculture) and this may be a significant limiting factor, especially in the case of small-island developing states. After all, any large-scale conversion will require much more than a rooftop, and island geography often restricts the feasibility of wind energy.

Some recent discussions aimed at solving or mitigating these potential challenges to sustainable energy:

http://cr4.globalspec.com/thread/20329

https://www.xing.com/app/forum?op=showarticles;id=8635831

http://www.sustainabilityforum.com/forum/sustainable-energy/2032-spatial-footprint-challenges-solar-energy-use.html