RENEWABLE ENERGY SYSTEMS

The information on these pages results from my researches into the potential for self-builders, or those aspiring to a self-sufficient lifestyle, to utilise renewable energy technologies on a domestic scale. These notes have also served as a way for me to organise my thinking about renewable energy. I don't for a moment pretend that this is a complete survey or represents fast-developing best practice. I don't have any formal scientific training and I have at times struggled to make sense of detailed technical data presented by manufacturers as a means of 'proving' that their equipment is the best. I have had to simplify some complex systems in order to describe them and don't discuss the technical aspects of their operation, even though this may be an important consideration when it comes to choosing specific equipment. I hope my comments will act as a stimulus to further enquiry and prompt questions by anyone who wishes to increase their independence from bought-in energy and fossil fuels.

The application of terminology such as 'Renewable Energy', 'Sustainable Energy', 'Zero-Carbon', 'Carbon-Neutral' and 'Carbon-Negative' is open to different interpretations and challenges. It is also necessary to differentiate between 'Embedded Energy' - the energy used in the manufacture, processing and delivery to the point of use of a piece of equipment, and the 'Operating Energy' - energy which that equipment consumes in order to function. Some equipment with low energy use in operation has very high embedded energy. Some would also argue that the source of both types of energy, and whether that is renewable, must be considered.

It is vital that renewable energy is not used as an excuse to consume energy. Super-efficient insulation, sustainable and intelligent building design, the best-rated appliances and lowest consumption lighting all come before installing renewable energy sources.

I hope to add to the information as I install one or more of these technologies in my own house, and to report on the performance which they achieve.

Renewable Energy comes from

• Sun as Light or Heat
• Wind as air movement
• Water as hydraulic force or as stored heat
• Earth as stored heat
• Biomass

Sometimes the term Sustainable Energy is used: in my opinion the systems which use these five sources cannot always be described as 'sustainable' if they require inputs of electricity from the grid to make them function.

None of these sources can be used directly, with the exception of the Sun as a passive source in buildings expressly designed to capture solar energy for space heating. All other sources must be somehow converted into a form useable for energy and this includes the Sun for water heating or electricity.

The principal technologies available to use in the early 21st. century in a domestic context are

• Solar Thermal panels: heat from the sun is captured as efficiently as possible and transferred to a fluid for indirect use in domestic hot water (DHW) systems, heating swimming pools and in space heating (most usually underfloor heating)
• Solar Photo-Voltaic panels: photons emitted by the sun cause a silicon wafer sandwich to move electrons in a circuit, for use as low voltage electricity
• Wind Turbines: air movement causes aerofoil blades to rotate, these drive an alternator to produce DC electricity (some systems are AC) - ignoring their use as a direct drive for water pumps
• Water Turbines: movement of a stream of water turns a turbine, which in turn drives a means of producing electricity
• A body of Water or a stream/river may also be used as a source of stored heat which can be extracted and concentrated
• The Earth beneath our feet contains stored heat which may be extracted and concentrated to provide space heating
• Biomass - the processed product of growing plants which absorb carbon-dioxide - is burned in suitable equipment to provide heat

The use of Water and Earth relies on the fact that both water and earth store heat, are always at a more stable temperature than the air, and for part of the year in UK are at a higher temperature than air.

Grants from Government and Non-Governmental sources do exist, all have restrictions and limits for private domestic use. The principal sources of information are the Low Carbon Buildings Programme and Clear Skies (see Links). All insist on installations using approved equipment and approved contractors. The cynic in me suspects that a self-builder on their own will end up paying as much with a grant as they could have paid by using equipment and contractors selected with their own judgement, i.e. grants benefit contractors not householders. Don't accept the restrictions imposed by a grant without checking thoroughly that the equipment and system design is equally as good as a setup you would have selected yourself, and could have obtained for the same or less money after getting several quotations. Be wary of companies promoting too heavily the grants which their services attract.

LINKS are intentionally kept to a minimum, entering key words into search engines will bring up thousands of sites.

Detailed comments on an individual approach to Sustainability:    www.earth.org.uk

Association for Environment Conscious Building:    www.aecb.net

UK Building Research Establishment:    www.bre.co.uk

Clear Skies:    www.clear-skies.org

Energy Saving Trust:     www.est.org.uk

Better Generation (lots of info. but they do sell stuff so care needed):    www.bettergeneration.co.uk

Greenspec (products and materials):    www.greenspec.co.uk

Low Carbon Buildings Programme:     www.lowcarbonbuildings.org.uk

Green Book Live (approved products and materials):    www.greenbooklive.com

Renewable Energy Association:     www.r-p-a.org.uk

Not forgetting Channel4 Grand Designs:    www.channel4.com/4homes

Further pages deal with each technology in turn, with discussion of the available systems and some links to futher sources of information. No single system is likely to provide a complete solution to a specific energy requirement, equally each has an important role in the right location.

Please click on a button to the left:

        SOLAR THERMAL PANELS

        SOLAR PHOTO-VOLTAIC PANELS

        WIND TURBINES

        WATER TURBINES

        GEO-THERMAL ENERGY - Water and Earth

      BIOMASS

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