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8.1: Define power and energy

Definition of power and energy

Definition power and energy

Energy is ability to do work so as to produce motion. You must have energy to accomplish work.

Power refers to the rate at which work is done. Therefore, you need energy to produce power. Without energy there is no power that can be produced.

Energy and power are related but totally are different concepts. A tank of petrol contain energy that combust petrol at certain time in mechanical energy to produce power of a car. The power is energy produced per unit of time. Therefore, more combustion of energy more power produced.

Power is found within our bodies, machines, in plants and bodies of animals, insects and birds.

Power is also present in natural forces like wind, tides, waves and water whose movements can be used to drive machines or generates electricity

8.2 Major sources of power

Concepts from this subtopic

a.       Identify major sources of power and energy

b.       Describe the origin of different types power and energy sources

c.       Identify the types of power and energy sources.

major sources of power and energy

The sources of energy are categorised as renewable and non-renewable.

         i.            Renewable energy sources:

Renewable energy sourcesis any energy source that is naturally replaced.

This source of energy is generated from sunlight, tides, wind, water, geothermal or hydroelectric power.

The energy is regarded friendly with environment because has minimal environmental pollution.

The renewable resource is sustainable it they carefully managed and maintained.

Some of this sources are described below;

(a)Biogas energy: is mixture of gases produced by decomposition of organic matter.

Such as waste from manure, plant materials, sewage, green waste or food waste.

The main components of biogas are methane and carbon dioxide.

Biogas is cheap than other source of energy and does not require specialised knowledge to operate.

(b)wind energy; is energy generated from wind.

Windmill is used to generate electricity and water pumping

Before harnessing wind energy, the research in the following variables such as speed, direction and persistency should be considered.

Then, wind turbine should be installed. A wind turbine operates on the following principle to produce electricity;

(i)The power from wind turns windmill that has three or two propeller

(ii) The motor is connected to main shaft that spins a generator to generate energy.

In Tanzania the utilisation of wind energy is encouraged due to increase of oil costs, frequent hydroelectric power cuts, and increase of power demand which is influenced by population growth.

Tanzania has areas of high wind potential that cover more than 10% of its land.

Research works show that Tanzania has a lot wind energy resources in areas of Great lakes, the plains and high land plateau regions of rift valley.

Area such as Makambako-Njombe and kititimo-Singida gave sufficient wind speed for electric generation.

The advantage of using wind energy is that,

   (a)it does not pollute environment

   (b) it occupies a small ground area

The limitation is that wind turbines can disturb or killing flying creatures 

(c)Solar energy; is generated from the sun using collector panels. The collected energy can be used to provide heat, light, or other form of electricity.

The distribution of solar energy depends on the overhead sun of particular place.

It is harnessed by using two methods:

(i) Through plates which are used to collect and reflect heat to power generator.

(ii) By using Photovoltaic cells (PV) composed of semi-conducting materials that convert sun rays into electric currents.

It is common used in many places for lighting homes and traffic roads as well as street lights.

The PV cells are combined to form solar panels.

The panel usually differ in size depend on purpose of installation.

Solar panels are placed on top of house, roofs or traffic light.

For adequate energy solar panels should face directly the light to generate higher electricity.

China,Geman, Italy, Japan and united States are leading countries possess biggest solar panels in the world.

In Tanzania solar energy is used as a source of power by 24.7% of household that jave access to electricity.

Solar energy is mostly used in rural areas by 64% of its people to compare to urban areas.

Advantages of solar energy

(i)It is friendly to environmental pollution

(ii)It is cheap after being installed. It does not require money for payment of monthly bills

Disadvanteges of solar energy

(i) It is expensive to buy solar panel

(ii) It can be affected by weather conditions. Solar panel unable to produce energy if there is high cloud cover on atmosphere

(d)Geothermal energy; is the heat energy generated and stored in the earth.

Utilising this energy involves pumping cold water into hot rock boreholes and extracting steam into another borehole.

Due to the force of hot water comes out, lead to drive the turbines to generate electricity.

It founds mostly in volcanic region.

Example of geothermal power in Tanzania found in Manyara, Mbeya, Mara and Rukwa.

Geothermal energy can be used for domestic purpose or industrial uses.

Disadvantages of geothermal energy is that it only produced in selected area.

(e)Hydroelectric power energy; is energy created due to flowing of water from highland or mountain and drive the turbine to generated electricity.

Establishing hydro-electric power plants

The reservoirs or dams are constructed across the river.

The power house is constructed with turbine installed

Then the water is directed to the turbine chamber. Water pressure cause the turbine to rotate.

As the turbine rotates the generators also rotates to produce electric power.

The power generated is then transported to transformers from where is transported to consumers.

Condition necessary for hydroelectric power production

 i.     Constant supply of water. This is possible if the area has heavy rainafall, natural lake or melting of ice.

ii.     There must be a ready market for the power generated

iii.     The presence of steep slope or waterfall

(f)Fuel wood: wood energy generated from wood extracted products through combustions process. The energy is used for cooking, heating, and generation of hydroelectric power. Fuel wood can be solid includes (firewood and charcoal produced from wood residual), liquid includes (bio-oil, bioethanol) and gaseous (wood gas).

About 2500 million people globally rely on wood fuel for heating and cooking. More than 1 million people in Tanzania engage in charcoal production and supply. 

2. Nonrenewable source of energy

Nonrenewable source of energy refers to the source of energy that cannot be re used. They are nonrenewable energy because their formation takes a long time usually millions of years. Fossil fuel such as coal, oil natural gas is nonrenewable source of energy. They originated from long period of time and formed under high pressure and heat; examples of non-renewable energy;

(a) nuclear energy is energy originates from the splitting of uranium atom. This process of splitting atoms is called fission. This generate heat to produce steam, which is used a turbine generator to generate electricity.

Because nuclear power plants do not burn the fuel, they do not produce greenhouse gas emissions that easily to be built in rural or urban region

Nuclear power is mostly generated in USA, France, Russia, China, Canada, Israel and United Kingdom.

Nuclear power also produces radioactive materials which increase health risks in the communities where the plants are located.

(b)coal energy: coal is a combustible black or brownish-black sedimentary rock with high amount of carbon and hydrocarbons.

Coal is formed when organic matter (plants) are sediment under high pressure and heat for millions of years. Amount of oxygen, nitrogen and moisture decreases with a time while the proportion of carbon increase.

Capacity of coal to give energy depends upon the percentage or carbon content (older the coal much the more its carbon content)

Coal is classified into three types (peat, anthracite, bituminous and lignite)

(i) Peat is first stage of transformation contain less than 40 to 50 percent carbon. Contain more smoke and more pollution.

It burns like wood, give less heat, emits more smoke and leaves a lot of ashes.

(ii) Lignite. is second stage of transformation containing 40 to 55 percent carbon. it is brown coal. It undergoes spontaneous combustion

Moisture content is high over 35 percent


(iii)Bituminous coal; it is soft coal most available and used. It contains 40 to 80 percent carbon

It is dense compact and normally black colour. It used in production of coke and gas

(iv) Anthracite coal; it hard and best coal contain 80 to 95 percent of carbon,

It has small proportion of moisture. Ignites slowly and burns with a good short blue flame.

There is little or no pollution. It used in iron smelting and also electric generation.

Coal energy generate electricity when used to heat water produce high pressure lead turbine rotates which lead to generate electricity

(c) Petroleum: is organic in origin and formed in pores spaces of sedimentary rock.

Still tube is inserted into the ground to trap the oil then is transported through pipelines for refinery process.

(d) Natural gas energy: it is commonly occurring alongside of petroleum

It is formed due to decomposition af animals and plants which produce heat energy and light energy.

Natural gas mainly composed of hydrogen, carbons and Methane

8.3: Methods of acquiring or extracting power and energy

Concept from this subtopic

a.    Methods of acquiring or extracting power and energy

(i) coal

It is extracted under the earth’s crust and is tapped by burning.

It is used in home activities like cooking and heating and also in industry for smelting.

During industrial revolution coal used in steam engine for navigation of Europeans to different part of the world.

(ii) Petroleum

Petroleum is mined from depth of the earth crust and passing through refinement process for using product. It is tapped by burning which produce mechanical energy and light energy.

(iii) Natural gas

It is mined in depth of the crust. Before using is refined as petroleum. Also is tapped by burning which produce mechanical energy and light energy.

(iv) Water

Energy from water can be extracted through natural or artificial energy.

Naturally can be tapped through river channel where turbine is installed to generate electricity.

Artificially can be tapped by directing water in pipes which drops in a turbine to generate electricity.

(v) Biomass consists of plant and animal life. Plant residues such as slashed grasses and dry dead leave can be burnt to produce light and heat energy.

Also animals waste such as dried dung cow may be burned to produce heat and light energy

And also can combined by plant residues to decompose to form biogas energy.

(vi) Nuclear energy; it involves nuclear fission and fusion.

Nuclear fusion involves fusing of nuclei of two light atoms, while nuclear fission involves the splitting of an atom.

The most exploited is nuclear fission which is carried in nuclear reactors lead to release of heat. This heat is used to heat water and produce steam that used to spin a turbine to generate electricity.

(vii) Solar energy; This energy is extracted using plates and photovoltaic cell (PV)

(a) Plate collect and reflect heat to power generator

(b) photovoltaic cell is composed of semi conducting materials that convert sun rays into electric current.

Photovoltaic cells are combined to form solar panel that placed top to the roof to generates electricity.

(viii) wind energy; is energy generated from wind.

Windmill is used to generate electricity and water pumping

Before harnessing wind energy, the research in the following variables such as speed, direction and persistency should be considered.

Then, wind turbine should be installed. A wind turbine operates on the following principle to produce electricity;

(i)The power from wind turns windmill that has three or two propeller

(ii) The motor is connected to main shaft that spins a generator to generate energy.

(ix) Geothermal energy; is the heat energy generated and stored in the earth.

Utilising this energy involves pumping cold water into hot rock boreholes and extracting steam into another borehole.

Due to the force of hot water comes out, lead to drive the turbines to generate electricity.

8.4: importance and uses of power and energy

Concept from this subtopic

(a) To explain the uses and importance of these types of power resources

The Use and Importance of Energy/Power Resources 

i.         The power and energy resources used in industrial development activities.

ii.       It used to run agricultural machinery such as tractors and harvesters such as petroleum. 

iii.      Petroleum used by machines in agriculture increases agricultural production

iv.      Environmental conservation: The use of solar, wind, biogas and energy helps to conserve the environment

v.          Improvement of Transportation sector because of the use of motor vehicles, ships, aircrafts, etc, all of which are powered by petroleum products. Improvement of transport and communication infrastructure

vi.         Source of employment

vii.       Source of foreign exchange and Source of government revenue

viii.      Social services and amenities: Most social services and amenities are facilitated by energy and power. For example, sports, games, schools, healthcare, and homes depend on power and energy in different ways.

ix.         Energy and power generated may be used for domestic purpose such as lighting, cooking, ironing.

8.5: Problems facing power and energy production

 a) Discuss the problems facing the process of power and energy harnessing.

b) Suggest ways of addressing power and energy harnessing

Problems facing the process of power and energy harnessing

         i.         Changing climatic conditions: Drought leads to rainfall scarcity and hence a drop in the volume of water in rivers. This problem affects the production of hydroelectric power and is one of the factors leading to low energy production in most parts of the world, especially in the least developed countries.

   ii.     Lack of capital: Energy and power production needs heavy investments in infrastructure, manpower and technology. All these investments require a great deal of capital.

     iii.      Lack of diverse energy sources in respective countries: Most counties have very few energy resources from which to extract power and energy. Worse still, some do not have a single energy resource, so they have to import the resources or power. For instance, uranium and geothermal steam are not found in many countries. Such countries extract power from only a few available resources such as water, wind or solar energy.

     iv.            Poor technology and lack of skilled personnel: Many developing countries lack the technology required to establish energy extraction infrastructures and the skilled personnel needed to perform that function. Most of the power and energy exploitation technology used in developing countries is very old and less efficient and productive. There are also very few people with the necessary skills for setting up and operating equipment as well as conducting research on power and energy production methods, facilities and technologies.

       v.            High prices: High prices for energy resources hinder energy and power output in most countries that have to import these resources from other countries. Oil is used for energy production. We have recently seen escalating oil prices worldwide. This leads to low purchase and hence low energy and power production. 

     vi.            Poor tools/ equipment for harvesting energy. Equipment needed for production of energy and power is very expensive and can thus not be afforded by many poor countries. As a result, they resort to inefficient and less productive obsolete technology which cannot produce sufficient power and energy to meet the ever-increasing demand for energy and power.

    vii.            Environment pollution: Energy and power exploitation is sometimes accompanied with the emission of harmful gases that pollute the environment. Coal burning, for example, releases tremendous quantities of carbon dioxide gas into the atmosphere. As such, many countries are either phasing out such energy generation technologies or spending a lot of capital to clean the coal so as to prevent environmental pollution. The power and energy production sector is, therefore, in great pressure to adopt technologies that minimize or cause no environmental pollution.

  viii.            Siltation: Accumulation of silt in dams used for generation of hydroelectric power reduces the volume of water in dams, hence resulting to low power generation. On the other hand, removal of the silt from dams adds to the cost of energy and power production and these costs are pushed on to consumers of energy and power.

ix.   Scramble for resources: River water is also used for irrigation of crops, domestic and industrial uses, fishing or preservation of flora or fauna. For example, river Nile is used for irrigation in Ethiopia (Gezira Irrigation Scheme) and, at the same time, required for production of hydroelectric power at Aswan High Dam, in Egypt.

  x.   If too much water is used for irrigation, little will be available for hydropower generation. 

xi.   This competition on the same resource can lead to international conflicts and even wars. Another example is coal which is used for domestic heating as well as for generation of electricity. This can curtail the generation of power and energy from coal if too much of it is used for domestic heating. 


Ways of addressing power and energy harnessing

            i.            The silt accumulating in dams should be dredged regularly in order to keep the volume of water constant. This will maintain the capacity of energy and power generation.

           ii.            Any form of environmental pollution likely to cause global warming and reduction in amount of rainfall should be avoided. People should not cut down trees indiscriminately as this can lead to drought and hence reduction in volumes of rivers needed for generation of hydroelectricity.

         iii.            Countries should diversify their energy generation sources in order to escape the effects caused by such problems as escalating oil prices and climate change.

         iv.            Developing countries should phase out the old energy and power generation technologies and instead adopt the new ones so as to cope with technological advancements to ensure that their energy generation is efficient and highly productive.

           v.            Research should be carried out often in order to improve energy and power production, as well as come up with new production methods. Research will also help in finding power and energy production methods that cause less or no environmental pollution.

         vi.            The governments should train their people the courses related to energy and power generation at schools, colleges, and universities so as to make them professionally competent in the field of energy and power generation and guarantee availability of skilled labours .

        vii.            Countries should set aside enough funds to be used for energy and power generation because success in this sector can boost the growth and development of other sectors since dormancy in energy and power sector can hinder industrial development and cause the country‘s economy to drop down.


8.6: Solar and Wind power in USA. H.E.P and Biogas in Tanzania

a) Evaluate the importance of power and energy resources in the focal countries

b) Summarize problems facing power and energy harnessing in focal countries

c) Propose solutions to these problems

d) Draw successful lessons from countries for better harnessing of power and energy resources in Tanzania.

The Importance of Power and Energy Resources in the Focal Countries

The USA is a technologically advanced country with a huge and very stable economy. It is a developed and heavily industrialized country with a great demand for power and energy required by its industries and its large population These and other factors have contributed to development of various power production resources. Solar and wind are among the diverse power resources in the USA.  Solar Power 

The U.S. is among the top countries in the world in electricity generated by the sun and several of the world's largest small-scale installations are located in the desert Southwest. Solar power includes small-scale solar power plants as well as local distributed generation, mostly from rooftop solar panels. The United States conducted much early research in solar devices and concentrated solar power. There are plans to build many other large solar plants in the United States. Many states have set individual renewable energy goals with solar power being included in various proportions. 

Solar power accounts for about 1% of the total national generation capacity. It is mainly exploited in the sunny areas of the country which include Nevada and California states. Rooftop solar panels Wind power 

Wind power is a branch of the energy industry expanding quickly over the last several years. U.S. Wind Generation (KW) by Year. 

Wind power accounts for 4% the total energy produced in the USA. Texas is firmly established as the leader in wind power development, followed by Iowa and California. Wind power is used to run farms, industries and for generating electricity that is fed to the national grid.


The importance of solar and wind power in the USA

      i.          Source of employment: Solar and wind energy industry is more labour-intensive. The industry supports thousands of people in the USA. 

     ii.          Industrial development: The energy and power generated is abundance and availability of cheap energy from wind and sunlight promotes industrial development.

   iii.          Conservation of non-renewable energy resources: Depending on renewable energy sources such as wind, solar and hydroelectricity for power and energy generation helps to conserve the non-renewable energy sources such as gas, coal and petroleum, they are conserved for future uses instead.

   iv.          Reduced environmental pollution:, generating sufficient power and energy from these resources will help reduce environmental pollution that could otherwise result due to dependence on non-renewable resources.

     v.          Improved standard of living: People employed directly and indirectly in the wind and energy industry earn cash which they spend on their daily needs 

   vi.          Development of other sectors of economy: Growth in power and solar industry creates positive multiplier effects. 

  vii.          Generation of revenue: Local governments collect property and income taxes and other payments from energy project owners

viii.          Stabilization of energy prices in future: Wind and solar energy is providing affordable electricity across the country right now, and can help stabilize energy prices in future. 

    ix.          Diversification of energy supplies: Using more wind and solar energy can lower the prices and demand for natural gas and coal by increasing competition and diversification of energy supplies


Problems facing solar and wind power in the USA

            i.            Generation of wind and solar power depends on prevailing weather conditions. In case of little or no sunshine due to prolonged cloud cover or if there is very low wind speed, then very little power will be generated. 

           ii.            People are still reluctant to change from dependency on the traditional energy sources, such as hydroelectricity. 

         iii.            The cost of installation of equipment for generating wind and solar power on a large-scale is very high.

         iv.            The cost of leasing land for building wind energy projects is very high. 

           v.            The industry is facing stiff competition from other sectors of energy and power, such as coal power, hydroelectric power, and geothermal power.

         vi.            Unequal government subsidies and taxes. Nuclear and fossil fuel technologies enjoy a considerable advantage in government subsidies for research and development, 

        vii.            Wind and solar power developers may have difficulty obtaining financing at rates as low as may be available for conventional energy facilities.

      viii.            Good wind sites are often located in remote areas, far from the cities where electricity is needed most. 




Hydroelectric power (HEP)

 Hydroelectric power contributes about 57% of the total power generated in Tanzania. The electricity supply industry is dominated by Tanzania Electric Supply Company (TANESCO). 

The company operates hydropower generation stations which include Kidatu, Kihansi, Mtera, Pangani, Hale, Nyumba ya Mungu and Uwemba, totalling 561 MW of electricity. 

TANESCO also generates thermal electricity using gas and diesel by plants located in various parts of the country. There are also independent power plants (IPPs) which produce thermal electricity from gas and diesel and then sell the generated power to TANESCO who feeds it to the national grid. 


Due to increasing demand for power and dwindling energy resources, there is need to develop alternative energy sources in Tanzania. One of such sources is biogas, which is used for heating, lighting, and cooking at homes, schools, hospitals, etc. Biogas is produced by anaerobic digestion with anaerobic bacteria or fermentation of biodegradable materials such as manure, sewage, municipal waste, plant material, and crops. Biogas technology in Tanzania was introduced in 1975. But it was not until late 2000s when a study of the biogas sector and how to improve it was conducted. Then the sector saw improved progress in domestic biogas uptake. The government is collaborating with different development partners to improve on existing technologies and to construct new biogas plants for particularly rural communities. It is estimated that about 700 biogas plants have been constructed in Tanzania. Most of these are in rural areas where raw materials such as livestock and poultry wastes and crop residues are easily and abundantly available.

 Importance of HEP and biogas production in Tanzania 

Hydroelectricity and biogas are very important power resources in Tanzania. 

Outlined below are some of the importance of producing these resources:

      i.          Hydroelectricity and biogas industry employs people who carry out energy production activities. 

     ii.          The hydroelectricity generated in Tanzania is used to power other industries and sectors of economy. It, therefore, leads to industrial development as well as other economic sectors in the country. 

   iii.          Biogas generation in rural areas has greatly helped to improve the living standard of the rural people. 

   iv.          The use of biogas and hydroelectricity has greatly reduced the problem of cutting down trees for firewood. This has consequently helped to prevent deforestation

     v.          Most of the biogas projects are undertaken by development partners from abroad. This has helped to improve the relationship between Tanzania and the partners‘ mother countries.

   vi.          The residue of the organic matter left back after biogas has been generated is used as enriched organic manure, which can supplement or even replace chemical fertilizers.


Problems facing HEP and biogas production in Tanzania 

            i.            Unreliable climatic conditions: Hydroelectric power generation relies on rain-fed rivers and dams. There has recently been occurring long dry spells which lower the volumes of rivers and dams, thus curtailing hydroelectricity generation. This leads to power rationing and hence interruption in economic production.

           ii.            Lack of adequate capital: Generation of HEP and biogas requires investment in installation of hydropower and biogas plants, respectively, all of which are hampered by availability of capital

         iii.            Siltation: The continuous accumulation of silt in the dams leads to reduction in water volume and hence low hydroelectricity generation. 

         iv.            Lack of skilled personnel: The establishment and operation of hydroelectric and biogas plants require skilled personnel. There are very few locals with the required expertise and professional skills to operate the projects. 

           v.            Reluctance by the people: People are still reluctant in adopting the biogas technology. Many people depend on use of wood as their major source of fuel. This has led to low investment in the industry and hence low production of the biogas.


Solutions to problems facing power production 

            i.            The silt in dams should be removed frequently so as to prevent reduction in water volume and the consequent drop in production.

           ii.            The government should invest in other forms of energy generation such as geothermal and coal power in order to reduce overdependence on hydroelectricity.

         iii.            Establishment of training institutions to train manpower on energy production technology. This will help produce skilled manpower to manage the power sector.

         iv.            Power generation must be liberalized in order to attract investors with sufficient capital to invest in the industry.

           v.            Conducting mass education to educate people to adopt the production and use of biogas. These can be done through seminars, trade shows and mass media, among other means. 


 Solutions to Problems Facing Power and Energy in USA

Harnessing in Focal Countries Propose solutions to problems facing power and energy harnessing in focal countries

Solutions to problems facing solar and wind power in the USA

            i.            Alternative sources of energy have been developed to supplement solar and wind power.

           ii.            People must be taught about the benefit of wind and solar power in order to persuade them to switch from traditional to modern energy sources.

         iii.            Government support as well as partnerships has enabled the setting up of power stations for wind and solar energy exploitation.

         iv.            The government must provide subsidies to solar and wind research and development as it is doing to conventional technologies.


 Lessons from Countries for Better Harnessing of Power and Energy Resources in Tanzania 

As far as energy production is concerned, Tanzania has a lot to learn from the USA. The following are some of the lessons that can be adopted and implemented:

 I.In USA, the energy sector is liberalized, so many private companies are allowed to generate and sell energy and power. Tanzania should also copy USA‘s example by allowing more private investors to participate in energy and power generation rather than allowing TANESCO to monopolize the energy production.

II. The USA has diversified its energy and power industry very well. The country generates power from different sources, ranging from nuclear to biogas plants. Tanzania can do the same by using natural gas, coal and uranium discovered in various parts of the country to produce the highly demanded power to boost her economy.

III. The government should form agencies to address the generation of solar and wind energy. There is great potential of wind and solar energy in Tanzania because of the presence of suitable conditions for harnessing these power recourses. There is plenty of wind and sunlight in the country to allow sustainable production of wind and solar energy, which can then be fed to the national grid to help solve the problem of energy in the country.

IV. The government should support the development of various energy sources by providing funds to local companies as well as creating favourable investment conditions to multi-million energy production companies to invest in the energy generation sector.

V.The USA uses her own experts to develop the energy industry. Tanzania should also train her own people so that they can take active part in building energy generation projects rather than depending on skilled personnel from outside the country.





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