Energy Sources
ENERGY SOURCES
Energy can come from either renewable or non-renewable sources. Renewable sources such as solar, wind and hydro-power are naturally replenished and produce very few greenhouse gas emissions when operating. Non-renewable energy comes from diminishing stocks of fossil fuels and can produce large amounts of greenhouse gases.
Using natural gas results in only about one third of the greenhouse emissions compared to grid electricity.
ELECTRICITY
Electricity is the most widely available energy source and the only one able to run the full range of household appliances. But it is the most greenhouse intensive energy source. It is also usually the most expensive per unit of energy used.
Renewable electricity systems are initially expensive to install but have low operating costs and minimum environmental impact.
GAS
Natural gas is less expensive to use than electricity and produces fewer greenhouse emissions. However, gas is also a non-renewable fuel. It is largely used for water heating, room heating and cooking. It can, however, also be used for clothes drying, as a vehicle fuel and even for refrigeration.
WOOD
Wood can be a renewable energy source if it comes from sustainably managed forests. Its use should make no net contribution to greenhouse gases if trees are planted to replace those used, but fossil fuels are usually used in collection and transportation.
OTHER RENEWABLE RESOURCES
Solar water heaters and passive solar building techniques reduce the need to use non-renewable energy sources. However use is limited in some climates because of seasonl limited sunlight.
In these instances the modules are connected to another power source for backup.
PHOTOVOLTAIC PANELS
Photovoltaic (PV) modules are panels made up of a chrystalline material that use the radiant heat from the sun and convert it to electricity. They have no moving parts and are therefore reliable and require little maintenance. PV panels can be expected to last 20 years or more. PVs are suitable for use in urban areas as they take up little space and make no noise.
There are different module types suited to different applications. Always seek expert advice before deciding which to use.
ORIENTATION
Solar modules produce most power when they are pointed directly at the sun. It is important to install them so that they receive maximum sunlight. Ideally they should be in full sun from 9am to 3pm in mid winter.
There are many factors that affect the output of a solar powered system. The type of panels, total daily sunlight, shading etc can all affect the efficiency of the sytstem. For this reason it is best to seek the advice of an expert before choosing ro installing a system.
Incorrect installation or installation is the wrong place can lead to damaged cells. There many things to consider before deciding to use this type of power system that can only be worked out with the assistance of a professional.
WIND GENERATORS
Wind generators or turbines are essentially modern wind mills that use the wind to turn a propeller that drives a generator. The most common is the 'horizontal axis' turbine with blades like an aircraft propeller and a tail or vane to direct it into the wind. Wind generators are more suited to non-urban areas as the turbine needs to be mounted on a tower and makes some noise in operation.
Electricity accounts for the largest portion of the energy used in households, but creates around 85 percent of the greenhouse gas emissions because most electricity is generated by burning fossil fuels.
Fuels such as coal, oil and gas are non-renewable energy sources.
Electricity created using renewable energy sources has less effect on the environment.
REDUCING ELECTRICITY CONSUMPTION
First and foremost electricity comsumption should be reduced by reducing demand through the use of efficient appliances and lighting and lifestyle changes. Only after this is done should you install a renewable system so that an oversized system is not installed.
This is particularly important for systems that must be self-sufficient. They do not have access to the electricity supply grid for back-up and you may have to resort to using expensive fuels such as diesel. For grid connected systems, using less electricity reduces the amount purchased from the grid or increases the amount that can be sold back to the grid. This saves you money.
GENERAL RULES