Solar

Solar power is the fastest growing renwable energy technology o ver the past decade. Over the decade 200-2010 the installed capacity of PV(photovoltaic) solar cells increased by a near actor of 30 from 1.4GW to 40GW⁷.

With such an abundant consistent supply solar energy seem poised to play a vital role in the future of a renewable energy.

Environmental considerations

Solar power generation is developed using two methods. Firstly is solar thermal which uses the heat of the sun to generate steam to turn a turbine. The second uses the physical phenomenon of photovoltaic devices which are materials that produce an electrical current when light is incident upon them. Neither of these types of power generating plants produce any form of emissions. Where they do impact upon the environment is that sheer size required for a utility scale plant. However unlike hydroelectric plants or wind farms which can often find themselves in areas of natural beauty or important ecosystems solar power stations work best in the most arid of conditions where there is often little plant or animal life. By retrofitting existing structures with solar panels and designing new structures to incorporate them otherwise unused space such as roof tops can be used to generate electricity that can either directly power the structure or be connected to the grid. By diretly powering a structure be it home or commercial premises this gives an extra benefit of reducing the load requirement of the central grid and in the case of business whose operating hours closely follow that of useable daylight this can be a very efficient use of the available solar energy.

In the case of the Photovoltaic semiconductors the manufacture of these devices is very energy intensive an as most of the world energy is currently thermal generated this means the production of PV arrays will produce roughly 10 percent the CO₂ of a traditional coal fired plant. As more and more renwable forms of energy are utilized though this figure will drop considerably. At present Si semiconductors are favoured but there are some other alternatives that contain toxic materials. One other environmental concern is that PVs often store excess energy in batteries so that they can continue to deliver electricity after the sun goes down. Batteries contain toxic chemicals that even with the best maintenance can leak and are difficult to dispose of.

Cost

At the moment PV’s and thermal solar plants are expensive and that is one of the main barriers to their wide spread installaition. The table below shows the cost of construction of the two types of solar generating plant. While they are considerably more expensive than current gas or coal plants the Solar CSP is actually cheaper than a traditional thermal plant with carbon capture and storage.

Table 6 ⁸