James Westwood take a look at the different forms of renewable energy you might reasonably consider for your home

So what actually is "renewable energy"?

In the simplest terms, it is naturally occurring, non-polluting and sustainable energy. It can occur as tidal, wave or wind power, as biomass crops, and can be sourced from rivers and lakes as hydroelectric power. The most powerful and sustainable source of renewable energy though, is solar (the sun's rays). Apparently, enough sunlight falls on the earth every minute to meet the world's energy demand for an entire year.

Which is the most useful renewable energy for me?

On a micro-scale in the UK, suitable for use in all sorts of businesses, farms, schools or homes, the two most accessible and useful forms of renewable energy are wind and solar. Don't switch off at this point because solar is much more than just solar panels. Iâ'l explain why. The sun's energy is captured in the ground, in bodies of water, and in the air, and this energy can then be harvested for our use. Think about swimming in the sea in summer compared with winter and why it is that the water is warmer? Likewise the sun's rays are the reason for the stable ground temperature (unless you live on a volcano) which at just 1m deep remains between 8-120C year round in the UK. So extracting heat from the ground or a large body of water like a lake is actually making use of solar energy.

Which technologies can capture this energy best?

Solar energy captured in land, water or air can be used for heating a home or business by way of a Heat Pump. Simply put, these Heat Pumps convert the stored low-grade heat collected from the heat source via clever use of refrigerants, heat exchangers and a compressor into useable high-grade heat ideal for heating properties with underfloor heating, conservatories, extensions and swimming pools. The heat pump does require a power source to operate the compressor but that said they can deliver up to five times the heat output compared with the comparable power required for operation.

Wind power is easily harnessed by modern Wind Turbines. They are not just the huge structures you see on hilltops or beside the motorway, but are now available in super-efficient forms that require little height, have a low visual impact, and are almost entirely noiseless too. Low maintenance and long-term government support and funding make them a viable proposition for commercial and residential situations alike. Imagine getting a cheque each year for the energy you have sold back to the grid?

Radiant solar energy can be captured and used either by a traditional solar panel system which provides hot water for homes or businesses, known as Solar Thermal, or via a Solar Photovoltaic (PV) system which converts the sun's radiant energy into electricity. Each of these systems is easy to fit to a roof, wall or mount as a freestanding structure, and requires little or no maintenance. Solar Thermal panels as a rule of thumb can provide up to 70% of the average household annual hot water requirement and are also ideal for year-round heating of swimming pools. PV systems provide electricity that can be used in-situ and qualify for government funding based on the quantity of electricity generated.

The conundrum

If you consider a renewable technology, choosing which one and what size is the difficult bit as they will pretty much always deliver something for you but getting them to work at their optimum performance makes all the difference. Therefore, it is necessary to arrive at the right solution to suit the specific parameters of any project or property, the budget, and the motivation and goals of the resident or management. Current fuel sources and their respective costs must be considered. The orientation of the property and aspect and shading of the roof will have a significant impact on any Solar Thermal or PV installation. Ground Source Heat Pumps need significant land from which to collect the stored solar energy. Wind Turbines are very effective but not ideal in highly urbanised situations. Replacing old and inefficient equipment or installing equipment for the first time in new-builds or renovations reduces the marginal increase in capital cost of a renewable system, while making direct comparisons against existing equipment does not. There are grants available for some systems for residential and commercial customers, but not for others. Just wanting to be 'green' is honourable enough, but remember reducing CO2 emissions is not directly linked with reducing energy consumption if changing a fuel source, as different fuels have different CO2 footprints.

The answer

Technologies are now highly efficient, systems are proven, reliable and reasonably priced, and the long-term price trend of mass produced power is upwards. Yes, it is a good time to invest in renewable technologies "but not for everyone as it does depend on a range of factors. Sorry, it's not a simple yes or no.

James Westwood, based in Ketton, runs Energy Now, a company offering Home and Business Energy Saving

Advice www.actonenergynow.co.uk Office: 01780 729099 Mob: 07790 692978