Growing energy needs and alternative energy resources

  

Energy is the capacity to do work i.e.to move matter. Energy is our most important resource. Energy availability may limit economic and population growth. Most of our energy comes from fossil fuels. Sun is the primary source of energy. According to the first law of thermodynamics , ‘energy and matter can neither be created nor destroyed’. The second law defines that, ‘energy cannot be completely recycled’. Life depends on energy flow through ordered structures of matter.

Growing need for energy

Energy is the most important and primary input for economic growth. Power generation and energy consumption are the  measures of economic development of any country. There are 7 billion people on

 earth who use energy each day to make them richer, more productive safer and healthier. Energy growth is directly linked to well-being and prosperity of nations.

According to International Energy Agency (IEA) data from 1990 to 2008, the average energy use per person increased 10% while the world population increased 27%.  Growth of energy consumption is very fast  in several developing countries because of industrial development, rapid urbanization and higher living standards. Coal use in world increased 48% from 2000to 2009. World annual coal production increased by 32%  from 2005 to 2011.

Coal fueled the industrial development in the 18th and 19th century. But oil became the dominant fuel during the 20th century. The per capita annual consumption by people in the US is 24.85 barrels of oil, 1.79 barrels in China and 0.79 barrels in India. In 2040, global energy demand will be about 30% higher compared to 2010 as economic output more than double and the population will grow nearly 9 billion people.

According to IEA, global electricity consumption is expected to increase 75% between 2007 and 2030, Developing countries have more than 80% of new need. Growing electricity demand will remain the biggest driver of energy needs. India is presently the fourth largest electricity producing country in the world.

Kinds of energy 

Energy comes in different forms such as heat (thermal), light (radiant), mechanical, electrical, chemical and nuclear energy. There are two types of energy:

1.    Potential energy – stored energy

2.    Kinetic energy – working energy

Energy is produced usually from fuel burning and atom splitting.  Heat is considered to be low quality energy because it is dispersed. It is commonly a by-product of mechanical work. Electricity is a high quality form of energy because  it can be transported through wires, stored in batteries and used to make other forms of energy.

Sources of energy 

Energy resources can be classified into two groups:

1.    Primary energy 

2.    Secondary energy 

Primary energy is an energy form found in nature.  Secondary energy refers to all sources of energy that results from the transformation of primary energy resources. For example electricity is a secondary energy obtained from burning coal in a thermal power plant. Primary energy resources can be subdivided into two forms as:

       i.            Non-renewable energy 

     ii.            Renewable energy 

The energy sources can also be classified into conventional and non- conventional energy sources.

Conventional energy  – energy sources which we are using it for a long time at a commercial scale.e.g. fossil fuels and hydroelectric power.

Non-conventional energy – energy sources which are in the process of development over the past few years. They are available in plenty and can be replenished naturally. E.g. solar, wind, tidal, geothermal and biomass.

Importance of non-conventional energy 

·       Clean and pollution free

·       Protecting global climate

·       Unlimited supplies

·       Energy price stability

·       Jobs and economy

·       Longevity and reliability

·       Proximity to demand for electricity.

Non-renewable energy 

A non-renewable energy can be defined as a resource that cannot be reproduced or re-made at a scale comparable to its consumption. Once depleted, there will be no more available for future use. For example fossil fuels (coal, petroleum and natural gas) take thousands of years to form naturally and cannot be replenished in a short period of time. Impurities in fossil fuels are a major source of pollution. The burning of fossil fuels produce large amounts of carbon dioxide, which contributes to global warming.
Global coal reserve is 940 billion tones. The coal reserves may last for the next 50 years. Coal is more polluting than oil and gas. The burning of coal produces gases like carbon dioxide, oxides of sulphur, nitrogen and carbon monoxide.

Renewable energy

Renewable energy resources can be defined as the resources that are naturally replenished, inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy is obtained from natural resources such as sunlight, wind, tides, waves and geothermal heat. Common applications of renewable energies are electricity generation and motor fuels. Renewable energy resources currently contribute to approximately 18% of total global energy consumption. Examples include:

1.    solar energy ,

2.    hydro power,

3.    tidal power,

4.    wind  energy and

5.    geothermal (energy from the heat inside the earth).

Sources of non-renewable energy 

Coal – is formed during the carboniferous age of geologic time scale. The  buried plant remains were  transformed into peat and coal due to the action of heat and pressure over a period of million years. Coal is made largely of carbon but also other elements such as hydrogen and oxygen. Burning coal generates large amounts of fly ash and bottom ash. Coal is the world’s largest source of energy for the production of electricity. Coal produces around 40% of the world’s electricity. The three main types of coal are lignite, anthracite and bituminous.

Petroleum – the word ‘petroleum’ means ‘rock oil’ or oil from the earth’. Oil is formed from the remains of animals that lived a million years ago in a marine environment. Crude oil is a complex mixture of hydrocarbons with small amounts of sulphur, oxygen and nitrogen. Crude oil is a smelly, black liquid. Crude petroleum is purified by fractional distillation. Due to its high energy density, easy transportability and relative abundance, oil has become the world’s most important source of energy.

Natural gas – is a naturally occurring hydrocarbon gas mixture consisting primarily of methane. Natural gas is described as a cleanest fossil fuel producing less carbon dioxide than either coal or oil. Natural gas is often used for heating, cooking and electricity generation. Natural gas is used for the production of fertilizers through the conversion of ammonia.

Alternative or Non-conventional energy 

Solar energy

It is the most readily available and diffuse source of energy. It is the primary source of all kinds of energy on earth. It originates in the sun as a result of thermo nuclear fusion reactions. Sun produces this energy in the form of electromagnetic radiations. Solar energy can be utilized through two different routes as solar thermal route and solar electric route.

Solar energy conversion

Thermal method

Solar energy is converted into heat by means of concentrators such as blackened sheet, multi-reflectors, etc. Solar cookers, solar water heaters, solar desalination plants, solar air heaters and solar steam generators are designed to work on solar thermal energy.
Photovoltaic method
A solar cell is essentially a semiconductor device which permits generation of electricity when light falls on it. Silicon is the most commonly used material in the production of the solar cells. Solar cells capture the photons from the sun rays and transform it into a stream of electrons producing electricity. This technology is known as photovoltaic technology. Solar photovoltaic systems have a wide range of applications such as lighting, water pumping and telecommunications. India is one of the six countries which have developed the technology for manufacture of poly-silicon material.

 Benefits of solar energy

1. Solar energy is abundant- available every where and every day.
2. Solar energy is non-polluting and eco-friendly.
3. It is convenient to install solar panels in the building structures.

Limitations of solar energy
1. Solar panels produce electricity only during day light and not on a cloudy day or at night.
2. Solar panels are more expensive to install.
3. The storage batteries need more care and replacement once in every 5 to 10 years.

Wind energy

Wind energy is a widely available and unlimited source of energy on earth’s surface. Wind is described as moving air. The air moves from an area of high pressure to low pressure. The turbines of wind energy power systems create electricity when the wind turns the blades. The typical turbine revolves at about 10 to 25 revolutions per minute and the type of wind to yield this rotation is 10 miles per hour. Wind energy has been used for pumping water for irrigation and milling grains for hundreds of years.Small wind turbines can primarily be used in battery charging. The batteries can be used for electricity supply for houses, hospitals, farms, telecommunication and navigation.

Benefits of wind power

1.    Clean, renewable and eco-friendly energy.

2.    Reliable and cost-effective.

3.    Wind turbines can be used to generate electricity in remote locations.

Limitations of wind power

1.    The strength of the wind power is  not constant at all times.

2.    Wind turbines are noisy, undesirable in appearance and easily damaged in thunderstorms.

Tidal power

Sea water keeps on rising and falling alternatively under the influence of gravitational pull of moon and sun. Daily tidal flows can be used to spin turbines to produce electricity. The benefits of tidal power include a free energy source, low operating costs and a moderate net energy yield.

Hydropower

Hydropower uses the kinetic energy of moving water to make electricity. The production of electricity is through the use of gravitational force of falling or flowing water. The energy in the falling water is converted into mechanical energy by using turbines and this mechanical energy is used to develop electricity.The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. Hydro power supplies about 20% of the world’s electricity and 6% of its total commercial energy. Hydropower is clean and non-polluting source of energy.

Geothermal energy

Geothermal energy is the heat of the earth’s interior. Heat contained in underground rocks and fluids is an important source of energy. Underground steam from geysers is used to generate electricity. Geothermal energy is transferred to underground concentrations of dry steam ( steam with no water droplets), wet steam ( a mixture of steam and water droplets) and hot water trapped in fractured or porous rocks at various places in the earth’s crust. Geothermal energy is used commercially in over 70 countries. It exists in Iceland, New Zealand, United States, Philippines and Italy.

Biomass energy

Biomass  is a renewable source of energy. Plants absorb solar energy by photosynthesis, incorporating carbon from the carbon dioxide of air in their tissues and convert into organic matter. This organic matter is called biomass and basically a form of solar energy. It includes wood, agricultural waste and garbage. Energy plantation is growing plant species to produce biomass for energy. Biomass supplies 11% of the world’s energy. It contributes 38 percent of energy in developing countries.

Biomass is a renewable  as long as trees and plants are harvested faster than they grow back. Burning biomass fuel adds much less sulfur dioxide and nitric oxide to the atmosphere per unit of energy produced. Biomass resources have a high moisture content (15-95%) which lowers their net useful energy.

They are classified into 3 groups:

1.    Traditional biomass – in solid fom (solid biomass fuel)

                     e.g Wood ,charcoal , animal,dung and peat.

1.    Non-traditional form – converted into liquid fuels (Liquid biomass fuel). E.g. ethanol, methanol.

2.    Biogas energy-Biomass degraded anaerobically to obtain gaseous fuel called biogas. Anaerobic fermentation of cattle dung  gives methane and carbon dioxide.

Bio-fuels

Plants, organic wastes, sewage and other forms of solid biomass can be converted by bacteria and various chemical processes into gaseous and liquid biofuels. E.g. biogas, liquid ethanol and liquid methanol. Methane can be produced by anaerobic digestion of manure from animal feed lots and sludge from sewage treatment plants.

 Biomass energy conversion process

1.    Gasification – it is a thermo chemical process of obtaining energy from solid matter in a gaseous form. In principle, the process is a thermal decomposition of organic matter in the presence of limited supply of air or oxygen to produce combustible gases.

2.    Pyrolysis – refers to combustion in a deficient supply of air or oxygen. Pyrolysis gives out carbon monoxide and methane, which are condensed to form tar and methanol.

3.    Direct combustion – thermal decomposition of organic matter is carried out in the presence of excess air liberating heat and leaving behind incombustible ash.

Nuclear energy

When an atomic nucleus is split apart (fission reaction), a tremendous amount of energy is released. This energy is both heat and light energy. The nuclear power plant uses uranium as a fuel. Uranium is an element that is dug out of the ground. It is processed into tiny pellets that are loaded into very long rods and the rods are put into the atomic reactor. Inside the reactor, the uranium atoms are split apart in a controlled chain reaction. This chain reaction gives off heat energy. The heat energy is used to boil water in the core of the reactor to produce steam. This steam turns a turbine to generate electricity.

There are two main types of nuclear reactors: water moderated reactors and fast breeder reactors.

Merits of nuclear power

1.    Nuclear reactor produces huge amount energy from small quantity of fuel.

2.    Nuclear power plant does not produce smoke or carbon dioxide. So it does not contribute to global warming.

3.    Nuclear power is reliable, cost-effective and  clean energy.

4.    Nuclear reactor produces a small volume of waste.

Demerits of nuclear power

1.    The fuel used is expensive and  is difficult to recover.

2.    The disposal of radioactive waste is very expensive and extremely dangerous.

3.    Nuclear accidents can spread radiation.

4.    If the cooling system fails, a melt down of atomic reactor is possible.

5.    The cooling water requirements are very heavy.

Sustainable conservation

Humans have extensively modified global environment. Humans have impacted the environment beyond their regenerative capacity. Resource consumption in the world is rising rapidly driven by population growth and rising wealth. Between 1960- 2000, the human population of the world has doubled. Current consumption and production level are 25% higher than the earth’s ecological capacity. This means that human beings are consuming the natural resources at a significant rate. Per capita consumption in industrialized countries is steadily increasing about 2.3 % per year.

The following extra -ordinary changes occurred in the 20^th century:

·       Human population increased from 1.5 to 6 billion.

·       The world’s economy increased by 15 fold.

·       The world’s energy use increased by 13 to 15 fold.

·       Fresh water use increased by 9 fold.

·       The irrigated area increased by 5 fold.

The 15% of the world’s population living in the high- income countries account for 56% of the total world’s resource consumption while the poorest 40% in low income countries account for only 11% of consumption. Energy from fossil fuels is consumed in relatively much greater quantities in developed countries. Most of the energy resources we use are non-renewable and much of the ecological damage is non-repairable.
Sustainability is a state of balance between resource use and the regenerative capacity of the earth. It can be described as ‘securing quality of life within the limits of nature’. The sustainability can be defined as “forms of progress that meet the needs of the present without compromising the ability of future generations to meet their needs”(Our Common Future 1987 : The World Commission on Environment and Development). Achieving sustainability is a balancing act between current needs and future needs.

Sustainability lies in the interplay of environmental quality, economic vitality and social equity. Ecological sustainability is the maintenance of life support  systems and the achievement of natural extinction rate of species. Environmental sustainability refers to the maintenance of natural capital (e.g. natural resources).

References

Camp  WG and Daugherty TB 2004 Managing our natural resources, 4^th edition, Delmar (Thomson Learning),NY,USA.

David Elcome 1998 Natural Resources – their use and abuse, Stanley  Thornes (publishers) Ltd, England.

McPherson GR and De Stefano S 2003 Applied Ecology and Natural resource management, Cambridge University Press, NY, USA.

Pandey BN 2006 Natural Resource Management, Mittal Publishers, New Delhi.