Introduction

Energy is an essential part of modern life but many people in the world, especially the poorest people living in developing countries, do not have access to adequate energy resources. They may have no centralized electricity or the supply may be erratic and unreliable. This is why decentralized power delivery is needed, whether provided through modern technologies such as solar photovoltaic panels or through more traditional technologies which can be improved to deliver better performance, such as charcoal production.

In the domestic setting in developing countries energy is primarily used for lighting, cooking and heating, and to power small appliances such as radios. Families that can acquire more efficient sources of power will have a better living environment. Solar lighting can replace kerosene lamps, making the home lighter for longer as well as safer and cleaner. Despite the initial costs, replacing older forms of power generation can ultimately save money for families who would otherwise be spending money on fuel on a weekly basis. Access to energy enables people to undertake income-generating activities that would otherwise not be possible. Even small amounts of energy can make a big difference in people's everyday lives and in the amount of money they can earn.

In rural areas energy is needed for agriculture and crop processing. Energy for water pumping helps to increase crop production through improved irrigation. Small-scale milling or grinding equipment can greatly improve the income of farmers and allow farming families to have some control over how they manage their crops. Powered oil-expelling equipment will increase the processing capacity.

Energy is not only required for agriculture; urban areas need energy and often do not have sufficient supplies. Small businesses and shops need energy. Hairdressers in Kenya make the most of the energy delivered through renewable sources to improve their service to customers and help increase their income.

Energy is also needed to power the communication revolution, allowing people to have access to mobile phones which bring a range of benefits, keeping families in touch with one another and improving income generation through better market awareness by allowing people to know the best time to sell their produce and where the best resources can be found.

In schools, electric lighting and computers help children learn, with access to the internet providing them the opportunity to know more about the wider world. Hospitals and health clinics cannot function effectively without energy. Importantly vaccines must be refrigerated to ensure they remain effective.

Although centralized energy delivery is growing in almost every part of the world, there remains a large unmet demand for energy and delivery is very uneven. Grid connection will not reach sufficient numbers of people in forthcoming years and supply from centralized grid systems will remain unreliable as demand outstrips supply. Decentralized energy delivery has the advantage that it can spread rapidly to remote areas and is economically more attainable. This means that the technologies described in this publication will be suitable for the many people who will otherwise be unable to access an energy supply.

This book brings together a selection of the technical briefs produced by Practical Action on the subject of energy. The work of Practical Action and others has been to enable people living in poverty to improve their living standards. One way of doing this is by improving access to energy. Small-scale renewable energy technologies are a practical way of delivering clean energy to rural populations, providing energy for lighting, radios and other small domestic appliances as well as supporting economic activities that will improve incomes. Access to energy can also be a driver for poverty reduction by enabling businesses to develop and production to grow. This may be through a village-scale initiative, such as a micro-hydro scheme which could supply energy to many people and their businesses through a mini grid, but it also includes standalone systems that are used by one household independently.

Not only do clean energy technologies improve the lives of people, they also help reduce environmental pollution by replacing fossil fuels. Consequently, some small-scale renewable energy projects have been financed by carbon credit schemes.

Solar energy

Solar energy can be captured in two ways. The more traditional approach is to capture heat using some sort of thermal device such as solar water heater, while the other is to generate electricity directly through the use of photovoltaic panels.

Solar photovoltaic energy is ideal for household systems or isolated applications such as solar water pumping. These systems are relatively easy to transport and install, and require very little operation and maintenance. Although running costs can be very low, for many people solar photovoltaic technology is still an expensive option in terms of the initial capital cost. However, solar photovoltaic technologies have been falling in price over the past few years and are likely to continue to fall even further in coming years. The price of solar panels fell by almost 50 per cent in 2011 according to Bloomberg New Energy Finance (BNEF). The overall cost of solar electricity is now cheaper than that produced by diesel generators when looking at periods of seven years or longer.

The falling cost of solar photovoltaic technology components is mainly a result of the economies of scale arising from increased production, rather than any radical changes in the technology. Commercial panels still only convert 15 to 18 per cent of the energy that reaches them, but this low efficiency is relatively unimportant compared to the cost. This reduction in cost means that the technology is becoming available to poorer households.

Small-scale solar thermal energy options are also discussed in this publication, concentrating specifically on solar drying and solar distillation. Solar thermal energy has some significant advantages over the more technologically advanced PV systems in that the initial investment can be very small and the running costs are also minimal. The technology can be manufactured locally on a small scale. However, many small-scale solar thermal energy technologies have not dramatically changed over the years and have, to some extent, been relatively neglected in comparison to the developments in solar PV. Solar water heating is perhaps the most widely used solar thermal technology. It has become common in some regions such as the Mediterranean and North Africa, while not much used in other regions. To a lesser extent solar water heating has progressed in a similar fashion to solar PV in that it has developed and expanded in...