Principles of renewable energy

Principles of renewable energy

1.1 Introduction

The aim of this text is to analyse the full range of renewable energy supplies
available for modern economies. Such renewables are recognised as
vital inputs for sustainability and so encouraging their growth is significant.
Subjects will include power from wind, water, biomass, sunshine and
other such continuing sources, including wastes. Although the scale of local
application ranges from tens to many millions of watts, and the totality is
a global resource, four questions are asked for practical application:

1 How much energy is available in the immediate environment – what is

the resource?

2 For what purposes can this energy be used – what is the end-use?

3 What is the environmental impact of the technology – is it sustainable?

4 What is the cost of the energy – is it cost-effective?

The first two are technical questions considered in the central chapters by
the type of renewables technology. The third question relates to broad issues
of planning, social responsibility and sustainable development; these are
considered in this chapter and in Chapter 17. The environmental impacts
of specific renewable energy technologies are summarised in the last section
of each technology chapter. The fourth question, considered with other
institutional factors in the last chapter, may dominate for consumers and
usually becomes the major criterion for commercial installations. However,
cost-effectiveness depends significantly on:
a Appreciating the distinctive scientific principles of renewable energy.
b Making each stage of the energy supply process efficient in terms of
both minimising losses and maximising economic, social and environmental
benefits.
c Like-for-like comparisons, including externalities, with fossil fuel and
nuclear power.
When these conditions have been met, it is possible to calculate the costs
and benefits of a particular scheme and compare these with alternatives for
an economic and environmental assessment.
Failure to understand the distinctive scientific principles for harnessing
renewable energy will almost certainly lead to poor engineering and uneconomic
operation. Frequently there will be a marked contrast between the
methods developed for renewable supplies and those used for the nonrenewable
fossil fuel and nuclear supplies.

 Wind energy conversion system

1.2 Energy and sustainable development

Sustainable development can be broadly defined as living, producing and
consuming in a manner that meets the needs of the present without compromising
the ability of future generations to meet their own needs. It has
become a key guiding principle for policy in the 21st century. Worldwide,
politicians, industrialists, environmentalists, economists and theologians
affirm that the principle must be applied at international, national and local
level. Actually applying it in practice and in detail is of course much harder!
In the international context, the word ‘development’ refers to improvement
in quality of life, and, especially, standard of living in the less developed
countries of the world. The aim of sustainable development is for the
improvement to be achieved whilst maintaining the ecological processes on
which life depends. At a local level, progressive businesses aim to report a
positive triple bottom line, i.e. a positive contribution to the economic, social
and environmental well-being of the community in which they operate.
The concept of sustainable development became widely accepted following
the seminal report of the World Commission on Environment and
Development (1987). The commission was set up by the United Nations
because the scale and unevenness of economic development and population
growth were, and still are, placing unprecedented pressures on our planet’s
lands, waters and other natural resources. Some of these pressures are severe
enough to threaten the very survival of some regional populations and, in
the longer term, to lead to global catastrophes. Changes in lifestyle, especially
regarding production and consumption, will eventually be forced on
populations by ecological and economic pressures. Nevertheless, the economic
and social pain of such changes can be eased by foresight, planning
and political (i.e. community) will.
Energy resources exemplify these issues. Reliable energy supply is essential
in all economies for lighting, heating, communications, computers, industrial
equipment, transport, etc. Purchases of energy account for 5–10% of
gross national product in developed economies. However, in some developing
countries, energy imports may have cost over half the value of total
exports; such economies are unsustainable and an economic challenge for
sustainable development. World energy use increased more than tenfold
over the 20th century, predominantly from fossil fuels (i.e. coal, oil and
gas) and with the addition of electricity from nuclear power. In the 21st
century, further increases in world energy consumption can be expected,
much for rising industrialisation and demand in previously less developed
countries, aggravated by gross inefficiencies in all countries. Whatever the
energy source, there is an overriding need for efficient generation and use
of energy.
Fossil fuels are not being newly formed at any significant rate, and thus
present stocks are ultimately finite. The location and the amount of such
stocks depend on the latest surveys. Clearly the dominant fossil fuel type by
mass is coal, with oil and gas much less. The reserve lifetime of a resource
may be defined as the known accessible amount divided by the rate of
present use. By this definition, the lifetime of oil and gas resources is usually
only a few decades; whereas lifetime for coal is a few centuries. Economics
predicts that as the lifetime of a fuel reserve shortens, so the fuel price
increases; consequently demand for that fuel reduces and previously more
expensive sources and alternatives enter the market. This process tends to
make the original source last longer than an immediate calculation indicates.
In practice, many other factors are involved, especially governmental
policy and international relations. Nevertheless, the basic geological fact
remains: fossil fuel reserves are limited and so the present patterns of energy
consumption and growth are not sustainable in the longer term.
Moreover, it is the emissions from fossil fuel use (and indeed nuclear
power) that increasingly determine the fundamental limitations. Increasing
concentration of CO2 in the Atmosphere is such an example. Indeed, from
an ecological understanding of our Earth’s long-term history over billions of
years, carbon was in excess in the Atmosphere originally and needed to be
sequestered below ground to provide our present oxygen-rich atmosphere.
Therefore from arguments of: (i) the finite nature of fossil and nuclear fuel
materials, (ii) the harm of emissions and (iii) ecological sustainability, it
is essential to expand renewable energy supplies and to use energy more
efficiently. Such conclusions are supported in economics if the full external
costs of both obtaining the fuels and paying for the damage from emissions
are internalised in the price. Such fundamental analyses may conclude that
renewable energy and the efficient use of energy are cheaper for society
than the traditional use of fossil and nuclear fuels.
The detrimental environmental effects of burning the fossil fuels likewise
imply that current patterns of use are unsustainable in the longer term. In
particular, CO2 emissions from the combustion of fossil fuels have significantly
raised the concentration of CO2 in the Atmosphere. The balance of
scientific opinion is that if this continues, it will enhance the greenhouse
effect1 and lead to significant climate change within a century or less, which
could have major adverse impact on food production, water supply and
human, e.g. through floods and cyclones (IPCC). Recognising that this is
a global problem, which no single country can avert on its own, over 150
national governments signed the UN Framework Convention on Climate
Change, which set up a framework for concerted action on the issue. Sadly,
concrete action is slow, not least because of the reluctance of governments
in industrialised countries to disturb the lifestyle of their voters. However,
potential climate change, and related sustainability issues, is now established
as one of the major drivers of energy policy.
In short, renewable energy supplies are much more compatible with sustainable
development than are fossil and nuclear fuels, in regard to both
resource limitations and environmental impacts .
Consequently almost all national energy plans include four vital factors
for improving or maintaining social benefit from energy:
1 increased harnessing of renewable supplies
2 increased efficiency of supply and end-use
3 reduction in pollution
4 consideration of lifestyle.