Going Green – where to start (part 2 of 2)

The previous post: Where to Start? – Energy! looked at the initial steps that could be taken when tackling the energy problem, as well as the use of technology to achieve the goal of reducing our reliance on coal based energy. In this post, we look at buildings becoming self sufficient through the production of renewable energy. A subject broad enough to warrant a post of its own.

On-site renewable energy options include photovoltaic systems, cogeneration (used in larger buildings), wind power, geothermal electric systems (using the Earth’s steam to make electricity), low-impact hydroelectric power systems and biofuel-based electrical systems (not easily applicable to buildings - more suitable to farms etc.) Of the above options, 3 are most easily applicable to residential projects:

1. The most commonly known of the above options is photovoltaic (solar power) systems which use the suns rays to generate energy. Photovoltaic is also the most user friendly / cost effective application for home use. Currently, solar power systems still require a fairly large initial investment (approximately R250 – R300,000 for an average size home to be independent of the grid) and the systems are not that efficient. But, the science is quickly improving and costs are continuing to come down. Conversely as electricity prices continue to increase, the pay-back period will get better. In warmer climates, where the highest demand usually occurs when the sun is at its hottest (airconditioning etc.), photovoltaics are helpful in reducing power usage.
2. Co-generation uses one fuel (gas, oil, or diesel) to produce two outputs—electricity and heat. But the plant costs make this feasible for large buildings only, and therefore not in keeping with this blogs target audience.
3. Wind power generates large amounts of electricity at low cost and with zero emissions. Wind turbines can be used alone (with their own battery storage system), or as part of a combination system, in which their output is combined with that of solar panels etc. Combining systems is useful for winter backup where cloudy weather and windy conditions occur simultaneously. Most importantly, before purchasing a wind power system it must be established whether or not your site has enough wind to generate the power to warrant the cost – as with solar power, the technology is improving rapidly, but can still be costly.
   

Generally speaking, each project is unique in terms of location, budget and design etc. and if you are serious about reducing your reliance on coal based (grid supplied) energy , then you need to consider which options will best suit your specific requirements. For this, it is worth getting professional advice and assistance.

It is also worth bearing in mind that like many European cities, Cape Town will soon be offering "Green Electricity" as an alterantive source for your energy supply. We'll bring you more details on this soon.