Energy and the environment

Energy and The Environment :

Energy and The Environment

Definitions:

Definitions Energy: The Ability to Do Work Power: The Rate at Which Energy is Used or Converted

Definitions:

Definitions Two forms of energy: Kinetic and Potential Kinetic energy is energy of motion For example a rubber band flying through the air has kinetic energy. When you are walking or running your body is exhibiting kinetic energy Waves in the ocean Plane in Flight

Definitions:

Definitions Potential energy is the stored energy of position possessed by an object. For example the heavy ball of a demolition machine is storing energy when it is held at an elevated position. A drawn bow is able to store energy as the result of its position. When assuming its usual position (i.e., when not drawn), there is no energy stored in the bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store energy by virtue of its position.

Energy in transition:

Energy in transition A waterfall has both potential and kinetic energy. The water at the top of Maracas Water Falls has stored potential energy. When the water begins to fall, its potential energy is changed into kinetic energy. This change in energy also happens at Niagara Falls where it is used to provide electricity from the transformation of mechanical and electromagnetic energy to parts of the northeastern United States.

Units of Measurement :

Units of Measurement Metric Prefix SI Symbol Meaning Actual value Tera T 10 12 1000000000000 Giga G 10 9 1000000000 Mega M 10 6 1000000 Kilo k 10 3 1000 Hecto h 10 2 100

Units of Power:

Units of Power Watt, W: (SI Unit) The Amount of Power equivalent to the use of 1 J for a period of 1 s (1 W = 1 Js -1 ) Horsepower, hp: (used for vehicle engines) 1 hp ≈ 750 W 1 000 W = 1 kW 1 000 kW = 1 MW (megawatt) 1 000 MW = 1 GW ( gigawatt ) 1 000 GW = 1 TW (terawatt)

Power Terminology Usage:

Power Terminology Usage Electricity Generation: Power plants are usually rated in MW. A 1 MW plant generates 1 000 000 J of electricity every second Electricity Consumption: Appliances are often rated in W. A 100 W light bulb uses 100 J of electricity every second.

Energy Consumption:

Energy Consumption A house, factory, etc, uses electrical energy at a particular rate. This rate, measured in Joules per second , or watts , is the power used. The rate at which electricity is used (the power) varies from time to time. The total electrical energy consumed is equal to the power used x the duration of use. A house using 1 kW of power for 1 hour uses 1 kWh of electrical energy. Electricity bills are usually calculated per kWh.

The kWh is a Unit of Energy:

The kWh is a Unit of Energy 1 kWh = 1 kW for 1 hour 1 kW = 1 kilojoules every second 1 h = 3 600 s Therefore: 1 kWh = 1 kJs -1 x 3 600 s = 3 600 kJ = 3.6 MJ

Units of Measurement:

Units of Measurement Joule (symbol J) The joule is the basic SI unit of energy defined as the amount of energy exerted when a force of one Newton is applied over a displacement of one meter. Newton (symbol N) Is the SI unit of force. A force of one Newton will accelerate a mass of one kilogram at the rate of one meter per second per second

Other Units of Energy:

Other Units of Energy Calorie, cal: (metric, used in nutrition) The Amount of Energy Needed to Raise the Temperature of 1 g of Water by 1 K (1 K = 1 o C ) The Specific Heat Capacity of Water British Thermal Unit, BTU: (Imperial, used in industry) The Amount of Energy Needed to Raise the Temperature of 1 lb of Water by 1 o F

Laws of Thermodynamics:

Laws of Thermodynamics First Law of Thermodynamics/ Principle of Conservation of Energy: Energy can neither be created nor destroyed, but can be converted from one form to another Second Law of Thermodynamics: Energy cannot be converted to Work with 100 % efficiency

Types of energy:

Types of energy Solar Heat Light Sound Electrical Chemical Nuclear

Conversions:

Conversions 1 cal = 4.184 J = 3.968 x 10 -3 BTU 1 J = 0.2389 cal = 9.484 x 10 -4 BTU 1 BTU = 252 cal = 1054 J 1 MJ = 1 000 kJ = 1 000 000 J 1 kcal = 1 000 cal = 3.968 BTU 1 quad, Q = 1 quadrillion BTU = 10 15 BTU 1 terajoule, TJ = 10 12 J 1 petajoule, PJ = 10 15 J = 1 000 TJ 1 exajoule, EJ = 10 18 J = 1 000 PJ

Energy conversion and efficiency of conversion:

Energy conversion and efficiency of conversion Energy conversion is the change from one form of energy to another. Which conversion is desired depends on our purposes.

Energy Conversion and Efficiency Example:

Energy Conversion and Efficiency Example When wood is burnt, chemical energy stored in the wood is converted to heat, which is used to cook, warm a room, drive a turbine, etc. However, if the wood contains 100 kJ of chemical energy, it is impossible to obtain 100 kJ of heat. More likely burning will generate about 30 kJ of heat. The rest of the energy will be converted to light, sound, or other forms. If 30 kJ of work is obtained from burning 100 kJ of wood, the energy conversion is 30 % efficient Efficiency = (Work Done ÷ Energy Input) x 100

Energy Conversion and Efficiency Example:

Energy Conversion and Efficiency Example The water cycle and hydro-electric power production are other examples of energy transformation. Heat energy from the Sun evaporates the water in lakes and oceans. The water vapour collects into clouds and falls as rain. The water flows downhill and can be restrained by a dam (potential energy). It is then released (kinetic energy) to turn turbines, in the production of electricity used to perform a variety of tasks in homes and industries.

Renewable and Non renewable sources of energy :

Renewable and Non renewable sources of energy There are two types of sources of energy in the world: renewable energy sources and non-renewable energy sources. Renewable energy sources include; solar energy, biomass energy, wind energy, tidal energy, hydro energy, and geothermal energy. Non-renewable energy sources include; oil, coal, natural gas, and nuclear energy.

Renewable Energy :

Renewable Energy Renewable energy is energy which is generated from natural sources i.e. sun, wind, rain, tides and has the capacity to replenish itself. They are available in plenty and by far most the cleanest sources of energy available on this planet. For eg : Energy that we receive from the sun can be used to generate electricity. Similarly, energy from wind, geothermal, biomass from plants, tides can be used this form of energy to another form.

Pros and Cons of using renewable energy sources:

Pros and Cons of using renewable energy sources Pros The sun, wind, geothermal, ocean energy are available in the abundant quantity and free to use. The non-renewable sources of energy that we are using are limited and are bound to expire one day. Renewable sources have low carbon emissions, therefore they are considered as green and environment friendly. Renewable helps in stimulating the economy and creating job opportunities. The money that is used to build these plants can provide jobs to thousands to lakhs of people. You don't have to rely on any third country for the supply of renewable sources as in case of non-renewable sources. Renewable sources can cost less than consuming the local electrical supply. In the long run, the prices of electricity are expected to soar since they are based on the prices of crude oil, so renewable sources can cut your electricity bills. Various tax incentives in the form of tax waivers, credit deductions are available for individuals and businesses who want to go green

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Cons It is not easy to set up a plant as the initial costs are quite steep. Solar energy can be used during the day time and not during night or rainy season. Geothermal energy which can be used to generate electricity has side effects too. It can bring toxic chemicals beneath the earth surface onto the top and can create environmental changes. Hydroelectric provide pure form of energy but building dams across the river which is quite expensive can affect natural flow and affect wildlife. To use wind energy, you have to rely on strong winds therefore you have to choose suitable site to operate them. Also, they can affect bird population as they are quite high.

Non-renewable energy :

Non-renewable energy is not replaced or is replaced only very slowly by natural processes. Primary examples of non-renewable energy resources are the fossil fuels --oil, natural gas, and coal. Fossil fuels are continually produced by the decay of plant and animal matter, but the rate of their production is extremely slow, very much slower than the rate at which we use them. Any non-renewable energy resources that we use are not replaced in a reasonable amount of time (our lifetime, our children's lifetime,...) and are thus considered "used up", not available to us again.

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Pros Non-renewable sources are cheap and easy to use. You can easily fill up your car tank and power your motor vehicle. You can use small amount of nuclear energy to produce large amount of power. Non-renewable have little or no competition at all. For eg : if you are driving a battery driven car your battery gets discharged then you won't be able to charge it in the middle if the road rather it is easy to find a gas pumping station. They are considered as cheap when converting from one type of energy to another.

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Cons Non-renewable sources will expire some day and we have to us our endangered resources to create more non-renewable sources of energy. The speed at which such resources are being utilized can have serious environmental changes. Non-renewable sources release toxic gases in the air when burnt which are the major cause for global warming. Since these sources are going to expire soon, prices of these sources are soaring day by day

Importance of energy to society How Energy is Used :

Importance of energy to society How Energy is Used In industrialized nations Residential and Commercial Industrial Transportation Electrical utility In less developed nations, most energy used is for residential purposes and in developing countries, most energy is for Industrial purposes.

QUESTION: Socio-economic dependency on energy use:

QUESTION: Socio-economic dependency on energy use