Renewable energy is generated from renewable natural sources such as wind, water, sun and geothermal heat. This includes wind power, solar power, hydroelectric power and ocean energy. Concerns relating to climate change and global warming, and a need to reduce carbon emissions, not to mention rising gas and oil prices, are gradually leading to domestic and commercial change towards renewable energy use. Replacement of current energy with renewable energy could cut carbon dioxide emissions by 50% by 2050, addressing the need for a cleaner energy source and replacement for the finite stocks of oil, coal and gas that are being depleted.
The most popular and fasted growing form of renewable energy is wind power, which is growing at a rate of 30% per year. Wind farms are on the increase, particularly on high altitude and offshore sites. No greenhouse gases such as methane or carbon dioxide are produced via this form of renewable energy. Solar energy is very popular, using photovoltaic panels, usually on roof tops to harness the sun’s energy. Water power uses the energy captured via hydroelectric dams or ocean energy, and is a clean renewable energy source. Biofuel is produced from the biomass of plants such as sugar cane, capturing the bi-product of ethanol or biodiesel to be burned in internal combustion engines or boilers.
More than 79% of a household energy use goes towards space and water heating, and so solar heating greatly reduces domestic energy bills. A renewable technology such as solar water heating is reliable with already established networks, and pays for itself within 7-15 years. It requires plumbing and heating expertise and is therefore not a DIY job for the householder. It can provide 40-60% of hot water requirements per year, with annual carbon emission reductions of 400kg.
Photovoltaics is another form of renewable energy using the sun’s energy. This is different from solar water heating. Photovoltaic cells use light to generate electricity. Photovoltaic panels can be fitted onto roofs and walls, and even integrated into the roof. This type of renewable energy is particularly useful in remote places which are not connected to the national grid. It works well in combination with wind power as photovoltaics are more effective in summer, while wind power is most effective in winter. Small scale stand alone photovoltaic applications are available. Most commonly seen and used are probably the garden lights that so many of us use nowadays that can be stuck into or onto a flower bed or hung from a garden wall or fence. Photovoltaic systems are more expensive than solar water heating systems. However, the advantage of this system is that it is easier to maintain due to the fact that it does not have moving parts, and can be integrated into a roof structure as tile replacements. Solar panels are now produced with greatly improved efficiency and are getting cheaper to buy and fit year after year.
Biomass refers to organic matter such as wood and crops which are grown specifically for energy use. It is a sustainable source which claims to be carbon neutral as the amount of carbon released during use is equal to the amount of carbon captured during photosynthesis. This is a valid argument only if crops and trees are replanted as they are harvested, to create a virtuous cycle of carbon capture and release. The most popular form of biomass used as a renewable energy source is the wood burning stove which can be used for water and space heating. Wood emissions when burnt contain very little nitrous oxide or sulphur dioxide, and therefore will not contribute to acid rain. Seasoned wood which is dried for 2 years emits very little smoke, and the ash can be used as a soil fertiliser. The burning of wood pellets is particularly popular in the US and becoming increasingly popular in the UK. Wood pellets are made from compressed wood shavings and saw dust.
Ground and air source heating
Another lesser known form of renewable energy is ground and air source heating. A few metres beneath the ground there is a constant temperature of about 10-15 degrees in the UK. For ground heating, and using a ground pump, this heat can be made use of in domestic housing as it is drawn up from the ground by a bore hole or ground collector. Air source heating takes the energy and heat from the air. This system is simpler than the system of ground heating, and is therefore much cheaper to install, but is less constant. The drawback with both these systems is that they require energy to power them although this is minimal.
The benefits to domestic households of renewable energy use are obvious. They save the user money, they do not contribute noxious gases into the atmosphere and they do not contribute as much to global warming.