Renewable Energy

A User's Guide

Andy McCrea

• Publisher: Crowood
• Year: 2013
• ISBN:
  9781847975447
• Topic: Technologie et ingénierie
• Subtopic: Ressources d'énergie renouvelable

Every day there are news reports that highlight spiralling energy costs, accelerating energy consumption, serious concerns over fuel security and fears that oil production may soon decline. All such reports are set against a background of the most serious threat to the world today - global warming and the devastating impact of climate change.This informative and wide-ranging book, written by an acknowledged expert, demonstrates how renewable energy technologies can help meet CO2 reduction targets. The author emphasizes that we need to use these technologies on a much wider scale to produce heat and electricity, and argues that if action is taken immediately it could make an enormous difference. He demonstrates how by installing a renewable energy technology in your home, you will be taking a step towards reducing your carbon footprint and ultimately you will be helping to save the planet. Now in a fully updated edition, this invaluable and well-illustrated book reviews the range of currently available renewable technologies that can provide energy as heat and electricity for our homes, businesses and industry, and also save harmful emissions, energy and money.The technologies are: Solar energy using solar panels for hot water and electricity; Heat pumps, which take heat from the ground for homes and buildings; Biomass fuels such as wood and waste, and even specially grown crops; Wind power, which can provide us with significant amounts of electricity in the decades ahead; Hydroelectricity where suitable rivers and streams are available; The potential of emerging technologies such as geothermal, wave and tidal power. An invaluable and informative book that demonstrates how renewable energy technologies can help meet CO2 reduction targets. Installing a renewable energy technology in your home will be a step towards reducing your carbon footprint. Reviews the currently available renewable technologies tht can provide energy for home, businesses and industry. Superbly illustrated with 78 colour photographs and 20 diagrams. Andy McCrea is a Chartered Engineer and was awarded an MBE for services to the electricity industry in 2004.

CHAPTER 1

Renewable Energy: An Introduction

To ensure that we move rapidly to a low carbon economy embracing the concept of zero carbon housing, it will be necessary to build super-insulated dwellings and integrate a range of renewable technologies at the design and construction stage. We have no hope of achieving ambitious targets for carbon reduction (60 per cent by 2050) without recourse to bold initiatives.

RENEWABLE ENERGY – NEW ENERGY?

Renewable energy, despite the inference in the name, is anything but new. Indeed, most of the technologies now involved have been in the service of man for a very long time. The current thirst to understand more about these technologies has been fuelled by a range of imperatives, perhaps most significantly a keener awareness that we have been abusing the Earth’s resources for too long and the growing anticipation that dire consequences are now just about to arrive. The perception is that the world’s weather has become more unpredictable and extreme, with almost daily reports of flooding, hurricanes, tornados, tsunamis and record-breaking temperatures – some of it on our very doorstep and much of it being blamed directly (rightly or wrongly) on climate change.

The sun, the wind and water power have been lightening the load of mankind for many centuries, but it is only recently that their potential has been pursued with unprecedented vigour. It always seems that our continental neighbours, in countries like Denmark, Germany and Sweden, are ahead in progress towards the necessary sustainable solutions, but recent advances and new government thinking on energy have made these renewable technologies much more accessible closer to home.

At first sight renewables appear to offer a utopian solution to the problems of modern energy demand, but everything comes at a price and their wide-scale deployment is anything but straightforward. For most governments of the world, fuel security and protection of the environment is now in the front line of policy and recently ‘green’ credentials have become vote capital on the hustings, with leaders from the major political parties trying to gain the edge by posturing as more environmentally friendly than their opponents.

There is also something inbuilt in each of us that recognizes that the environment is precious and its despoilment is wrong – even though we continue to demand more and more energy with apparent disregard for the consequences. As we shall see, one challenge of the zero carbon house concept is that the demand for electricity to drive our ever more sophisticated electronic appliances and entertainment systems is rising steadily. It is a fact of life that energy is central to our modern civilization but concerns about climate change, combined with rising energy costs and a fear of uncertainty around future energy supplies, have fuelled the drive for greater delivery of renewable energy. We all now aspire to minimize our carbon footprint and hope for a sustainable energy future that will provide us with the standard of living we have come to accept, but which will not compromise that of future generations. Renewable technologies appear to offer a partial solution, providing both low carbon heat and electricity (on the shoulders of conservation and energy efficiency) to help us move forward on this objective.

The aim of this book is to bring greater insight to some of the huge number of people who want to know more about renewable energy and how they can get involved with it. Over the last couple of decades the idea of making electricity and heat for our homes using renewable energy has moved from being a fringe, often DIY, pursuit to a mainstream business worth billions to the world’s economy. Much of this advance has been as a result of government support through a variety of grant programmes and through the awareness-raising activities of organizations involved in this area. I have called the book ‘a user’s guide’ rather than ‘a beginners’ guide’, as my original intention had been, because there is a higher level of awareness now about the issues (and the devices) and this allows me to move directly to the technologies themselves and review them in a little more detail. There is also a good deal of interest, fuelled by the media (and the weather!), in the whole area of climate change. It seems that people genuinely want to know how they can do their bit to improve their carbon footprint from a size 12 to a size 7. The technologies involved are now at a reasonable level of sophistication and the proper design and installation of renewable energy systems in the home or in businesses can deliver effective, reliable, affordable heat and electricity.

Figure 1: BAXI Ecogen Domestic CHP. At the heart of the domestic CHP unit is a Stirling engine, controlled by a battery of microcomputers, which produces space heating and electricity. The model shown is fuelled by natural gas and produces around 8kW of heat and 1.1kW of electricity. Work is in progress to develop similar CHP engines that can operate on a range of fuels including biomass.
(Author/www.baxi.co.uk/ecogen)

WHAT IS RENEWABLE ENERGY?

The term ‘renewable energy’ is frequently confused with ‘recycling’ but, despite the tenuous links, the two are different. Renewable energy may be defined in various ways that sometimes include different technologies (hydro, for example, is often omitted). A suitable definition might be that renewable energy is obtained from sources that are essentially inexhaustible (or that may be replenished), unlike, for example, the fossil fuels, of which there is a finite supply. In particular, they emit no greenhouse gases or are ‘emissions neutral’ over their lifetimes. They are also often referred to as ‘energy sources replenished by natural phenomena’ (this excludes any use of nuclear fuels). For the purposes of this book, renewable sources of energy are wood (bioenergy), some wastes, deep-geothermal energy, wind, solar photovoltaic (PV) and solar thermal energy (collected using solar panels and heat pumps). More recently, marine energy from the oceans, such as wave and tidal energy, have been included. Heat pumps use heat energy from a range of sources that, relatively speaking, are not particularly warm – for example the air, the ground (a couple of metres below the surface), lakes, rivers or even the sea. This is referred to as ‘low-grade heat’ and it requires to be ‘pumped-up’ using electricity to heat water (or air) to a more useful temperature (30–40°C). The same heat pumps may also be used (in a different configuration) to provide space cooling if necessary.

Associated terms are in common usage, such as microgeneration, embedded generation and alternative energy. In this book I will stick to ‘renewable energy’ and will address the principal heat and electricity technologies noted above. Microgeneration is a specific term defined in the UK Energy Act, 2004, as the generation of electricity up to 50 kilowatts (kWe), or by the production of heat up to 45 kilowatts thermal (kWth), by any plant that relies wholly or mainly on a source of energy or a technology in the following list: biomass, biofuels, fuel cells, photovoltaics, water (particularly small-scale hydroelectric plant), wind, solar power, ground/air heat pumps, and combined heat and power systems (CHP). A domestic CHP o...