**2. What is energy efficiency?**

50 Sustainable Growth and Applications in Renewable Energy Sources

Renewable energy is energy which comes from natural resource such as sunlight, winds,

The first law of thermodynamic says that the total amount of energy on our planet remains constant. The second law states that as forms of energy are expended they become less easily

 First law of thermodynamics: *A change in the internal energy of a closed thermodynamic system is equal to the difference between the heat supplied to the system and the amount of work* 

The first law of thermodynamics asserts the existence of a state variable for a system, the internal energy, and tells how it changes in thermodynamic processes. The law allows a given internal energy of a system to be reached by any combination of heat and work. It is important that internal energy is a variable of state of the system whereas heat and work

The first law observes that the internal energy obeys the principle of conservation of energy, which states that energy can be transformed (changed from one form to another), but cannot

Second law of thermodynamics: *Heat cannot spontaneously flow from a colder location to a* 

The second law of thermodynamics is an expression of the universal principle of decay observable in nature. The second law is an observation of the fact that over time, differences in temperature, pressure, and chemical potential tend to even out in a physical system that is isolated from the outside world. Entropy is a measure of how much this process has progressed. The entropy of an isolated system which is not in equilibrium will tend to

When coal, gas or oil is burnt, it rapidly converts a relatively easily available and concentrated source of energy into a much less available form: dispersed exhaust gases. A high concentrated energy source, built up over millions of years quickly gone up in

Using renewable energy however merely taps into a natural flow of energy, sunlight, moving water, wind, biological or geothermal process. These are part of natural cycles of highs and lows. Their energy is truly renewable as it remains available to the same degree

Renewable energies include wind, ocean, wave and tides, solar, biomass, rivers, geothermal (heat of the earth) etc. They are renewable because they are regularly replenished by natural processes and are therefore in endless supply (Fatona, 2009; Jacobson, 2009). They also can operate without polluting the environment. Technologies have been developed to harness these energies and such technologies are called renewable energy technologies (RET) or sometime also called "Clean technologies" or "Green energy" (Pearce et al, 1989). Because renewable energy are constantly being replenished from natural sources, they have security of supply, unlike fossil fuels, which are negotiated on the international market and subject to international competition, sometimes may even resulting in wars and shortages. They

1. Their rate of use does not affect their availability in future, thus they are inexhaustible. 2. The resources are generally well distributed all over the world, even though wide spatial and temporal variations occur. Thus all regions of the world have reasonable

increase over time, approaching a maximum value at equilibrium.

smoke. So, burning fossil fuels is high-entropy way of using energy.

and is not depleted any more than it otherwise would be by using it.

have important advantages which could be stated as follows:-

access to one or more forms of renewable energy supply.

plants growth, rain, tides and geothermal heat which are naturally replenished.

*done by the system on its surroundings.*

change the state of the system.

be created or destroyed.

*hotter location.*

available. That is entropy: the slow winding down of available energy (Jacobson, 2009).

Energy efficiency means improvement in practice and products that reduce the energy necessary to provide services like lightning, cooling, heating, manufacturing, cooking, transport, entertainment etc. Energy efficiency products essentially help to do more work with less energy. Thus, the efficiency of an appliance or technology is determined by the amount of energy needed to provide the energy service. For instance, to light a room with an incandescent light bulb of 60w for one hour requires 60w/h. A compact florescent light bulb would provide the same or better lighting at 11w and only use 11w/h. This means that 49w (82% of energy) is saved for each hour the light is turned on.

Making homes, vehicles, and businesses more energy efficient is seen as a largely untapped solution to addressing the problems of pollution, global warming, energy security, and fossil fuel depletion. Many of these ideas have been discussed for years, since the 1973 oil crisis brought energy issues to the forefront. In the late 1970s, physicist Amory Lovins popularized the notion of a "soft energy path", with a strong focus on energy efficiency. Among other things, Lovins popularized the notion of negawatts—the idea of meeting energy needs by increasing efficiency instead of increasing energy production (Krech, 2004).

Lovins viewed the energy problem not one of an insufficient supply of oil and other conventional energy sources, but rather as one of inefficient energy use, coupled with lack of development of renewable energy sources. Lovins argued that conventional energy production was both energy intensive and a source of substantial pollution. With his reformulation of the energy problem, "environmentalists criticized plans for large-scale energy developments, especially those relying heavily on nuclear power".

The "soft energy path" assumes that energy is but a means to social ends, and is not an end in itself. Soft energy paths involve efficient use of energy, diversity of energy production methods (matched in scale and quality to end uses), and special reliance on co-generation and "soft energy technologies" such as solar energy, wind energy, bio-fuels, geothermal energy, wave power, tidal power, etc (Nash, 1979).

Renewable Energy Use and Energy Efficiency – A Critical Tool for Sustainable Development 53

6. Reduce the negative environmental and human health impacts from energy production

The World Summit on Sustainable Development (WSSD) in Johannesburg in 2002 recognized the important role of energy for reaching millennium development goals. Access to affordable, reliable and sustainable energy is essential to sustainable development (Hasna, 2007). An adequate solving of energy problems will contribute to achieving progress across all pillars of sustainable development; social, economic and environmental and in meeting the UN millennium goals. Although there are no MDGs on access to energy, WSSD recognized that inadequate access to energy is both a cause and an effect of poverty

"*Take joint actions and improve efforts to work together at all levels to improve access to reliable and affordable energy service for sustainable development sufficient to facilitate the achievement of the Millennium Development Goals, including the goal of halving the proportion of people in poverty by 2015, and as a means to generate other important services that mitigate poverty, bearing in mind* 

"Sustainable development" has been defined best by the Brundtland Commission as development that meets the needs of the present without compromising the ability of future generations to meet their own needs (Hasna, 2007). Adequate and affordable energy supplies has been key to economic development and the transition from subsistence agricultural economics to modern industrial and service oriented societies. Energy is central to improved social and economic well being and is indispensable to most industrial and commercial wealth organization. It is the key for relieving poverty, improving human welfare and raising living standards. But however essential it may be for development, energy is only a means to an end. The end is good health, high living standards, a

Much of the current energy supply and use, based as it is, on limited resources of fossil fuels, is deemed to be environmentally unsustainable. There is no energy production or conversion technology without risk or waste. Somewhere along all energy chains - from resource extractions to the provision of energy service – pollutants are produced, emitted or disposed of, often with severe health and environmental impacts (Dasgupta, 2001; Fatona, 2009). Combustion of fossil fuels is chiefly responsible for urban air pollution, regional acidification and the risk of human – induced climate change (Dasgupta, 2001; Fatona, 2009). Achieving sustainable economic development on a global scale will requires the judicious use of resources, technology, appropriate economic incentives and strategic policy planning at the local and national levels. It will also require regular monitoring of the impacts of selected policies and strategies to see if they are furthering sustainable development or if

When choosing energy fuels and associated technologies for the production, delivery and use of energy services, it is essential to take into account economic, social and environmental consequences (Ott, 2003; Wallace, 2005). There is need to determine whether current energy use is sustainable and, if not, how to change it so that it is. This is the purpose of energy indicators, which address important issues within three of the major dimensions of

7. Increase employment through interactions e.g. in industry, housing, transport.

**3. Renewable energy and sustainable development** 

*that access to energy facilitates the eradication of poverty*" .

sustainable economy and a clean environment.

they should be adjusted (Arrow et al, 2004).

sustainable development: economic, social and environmental.

and use.

and recommended the following:

Soft energy technologies (appropriate renewables) have five defining characteristics. They (1) rely on renewable energy resources, (2) are diverse and designed for maximum effectiveness in particular circumstances, (3) are flexible and relatively simple to understand, (4) are matched to end-use needs in terms of scale, and (5) are matched to end-use needs in terms of quality (Nash, 1979).

Residential solar energy technologies are prime examples of soft energy technologies and rapid deployment of simple, energy conserving residential solar energy technologies is fundamental to a soft energy strategy. Active residential solar technologies use special devices to collect and convert the sun's rays to useful energy and are located near the users they supply. Passive residential solar technologies involve the natural transfer (by radiation, convection and conduction) of solar energy without the use of mechanical devices.

Lovins argued that besides environmental benefits, global political stresses might be reduced by Western nations committing to the soft energy path. In general, soft path impacts are seen to be more "gentle, pleasant and manageable" than hard path impacts. These impacts range from the individual and household level to those affecting the very fabric of society at the national and international level.

Lovins recognised that major energy decisions are always implemented gradually and incrementally, and that major shifts take decades. A chief element of the soft path strategy is to avoid major commitments to inflexible infrastructure that locks us into particular supply patterns for decades.

Lovins explained that the most profound difference between the soft and hard paths — the difference that ultimately distinguishes them — is their different socio-political impact. Both paths entail social change, "but the kinds of social change for a hard path are apt to be less pleasant, less plausible, less compatible with social diversity and freedom of choice, and less consistent with traditional values than are the social changes which could make a soft path work".

Moving towards energy sustainability will require changes not only in the way energy is supplied, but in the way it is used, and reducing the amount of energy required to deliver various goods or services is essential. Opportunities for improvement on the demand side of the energy equation are as rich and diverse as those on the supply side, and often offer significant economic benefits.

In most places, a lot of energy is wasted because industries, power companies, offices and households use more energy than is actually necessary to fulfill their needs. The reasons is because they use old and inefficient equipment and production processes; buildings are poorly designed; and because of bad practices and habits. With energy efficiency practices and products, nations can save over 50% of the energy being consumed. Using energy more efficiently would:

