Following the principle of “Savings First, then Production,” it may be possible to avoid having to produce energy at all if you can reduce your consumption by a large enough margin. This is how we propose addressing our energy challenges:
- Water Heating – go Solar or Heat Pump
- Cooking – convert to Gas (natural/bio if available, or LP if not)
- Heating – Use Gas (natural/bio if available, or LP if not)
- Cooling – Avoid/reduce air-con, use natural ventilation or fans if possible, paint your roof a lighter colour, using refractory ceramic paint
- Dish/Clothes Washing – set machines to cool or warm, energy saving mode
- Lighting – Convert all incandescent bulbs to LED or CFL – link to 1f below
- Other – switch off plugs, do not leave idle chargers connected
Energy production is an expensive exercise and all Savings option (see above) will need to be exhausted before taking this step. Once you have reduced energy consumption as far as possible, and only then should you consider production, asyou will not be needing to produce as much energy as before those savings.
But Energy production is an expensive exercise because after savings, and before any generating equipment can be brought on line, non-productive infrastructure (specialist design, wiring and cabling, inverters, isolators plus batteries and charge controllers where energy storage is desired) is required for integrating the energy to be produced with your existing electrical infrastructure. The smaller the scale of production, the higher the relative cost of the non-productive infrastructure (eg 50% infrastructure cost for small systems < 2kW) and the more expensive the overall exercise per watt. Larger scale production enables efficiencies which make the infrastructure less expensive relative to the overall cost of the system (eg 10% or less of total system costs for non-productive infrastructure for systems of >10kW).
The available technologies, depending on location, site conditions and resources, are generally regarded as the following in order of most common/cheapest to most unlikely/expensive:
- Solar PV – in sunny conditions such as most of South Africa enjoys, this technology remains the best value for money and first option
- Wind – represents challenges from a Health and Safety point of view in built environments and from an environmental point of view wherever it is located. This technology requires average wind speeds of > 5m/second, usually in elevated or wind-channelled locations to be remotely viable.
- Bio-Gas – (methane) should be considered if it can be affiliated to a poultry or livestock (agricultural) or a high food wastage operation such as a restaurant. Raw, untreated sewage is a source of bio-gas but this is required in high quantities (eg schools) if it is to represent a meaningful energy supplement. Bio-gas can be used to run a diesel generator for conversion to electricity, but t is most often used for cooking or heating.
- Small Hydro – also represents an environmental challenge since it will affect the eco-system of riverine environments, but there are less invasive technologies available which can mitigate this impact. Even at the smaller-scale (<5kW), this technology requires a minimum of a 10m head and a flow-rate of >100l/minute to be viable.
Meeting short term demands with long term solutions!