Lesson 2: Energy Utilization
We need energy to maintain physical comfort, to win and to manufacture useful materials and artefacts; for transport, for communications, agriculture and for industry. Thus, the main users of controlled energy are transport, agriculture, industry, commerce and households.
Transportation is the movement of people and goods from one place to another. Types of transport include road, rail, air, water, conveyers and pipeline. Transportation depends on continuous supply of energy. Over a quarter of all controlled energy is used for transportation of people and goods.
The transportation sector throughout the world is almost entirely dependent on energy derived from oil. Automobiles are powered by gasoline (petrol), aeroplanes by jet fuel (kerosene), and trucks, trains, and ships by diesel oil. Conveyers, cranes, robots and pipelines use motors and pumps, which are powered by electricity, some coming from oil as the primary energy source.
In ships and aircrafts, fuel is carried along and burnt in internal combustion engines to provide the needed energy. There is no limit to the route of operation. Considering road and rail transport, there are two basic class of vehicles: those that carry their fuel with them, and those that ‘pick up’ energy (electrical energy or solar energy) as they move along. Most vehicles at present use internal combustion engines and carry their fuel (gasoline/petrol, diesel or gasohol) along with them. This type of vehicle is popular because it has lots of advantages including the following:
- There is no limit to the distance that the vehicle can travel.
- There are no restrictions of access on the normal road network.
The disadvantages, however, include:
- Atmospheric pollution
Vehicles that pick up their energy as they go along include trams, monorail vehicles, underground trains, and some main line trains. Some vehicles also draw their power from batteries and/or solar panels. These types of electrically operated vehicles are, however, found on small scale. Electrically propelled vehicles have the advantage of being pollution free when the source of electricity does not use fossil fuel as the primary energy. Additionally, such vehicles are quiet in their operation. For electric road vehicles, recharging of batteries consume more energy than that consumed by vehicles driven by fossil fuels (from 1.4 to 4 times as much, depending on use). The energy used by electrically operated vehicles must be generated somewhere and depending on how it is generated, it is possible that the damage to the environment may be greater than the conventional automobiles.
The disadvantages of electrically operated vehicles include:
- Danger posed by the magnetic field produced by the electric current in overhead wires.This can be harmful to both humans and animals.
- Restriction to definite routes
- Visual pollution caused by the wires and the gantries.
- Limited range of electric road vehicles. The distance that they cover is limited by the stored energy.
It would not be complete looking at energy utilization in the transport sector without mentioning pipeline transportation, people movers and material-handling equipment. Pipeline transportation is the movement of bulk cargo through a tube or a pipe. Pipelines are used to transport a variety of fluids including oil, natural gas, water and liquid waste (sewage). The energy for pipeline transportation comes manly from electricity. Regarding people movers, several on-site devices have been designed to transport people. Notable among them include elevators (lifts), escalators and cable car (gondola). Energy for powering these devices comes from electricity. Elevators and escalators are two common devices found on offices and residential buildings. Gondola is a car suspended from cables and used to carry people to the top of mountains or across rivers.
The manufacturing process requires devices that are able to handle and move materials in an efficient manner. Many special material-handling equipment have been developed to make manufacturing more efficient. They include: conveyers, industrial trucks, robots and cranes. Conveyers are devices that move materials over a fixed path. These may be belts, rollers or overhead carriers. Energy for powering them mainly comes in the form of electricity. On the other hand, industrial trucks may be operated on oil or electricity derived from batteries. The most common industrial trucks are called forklifts because of the fork-like device on the front of the vehicle that is used to lift and carry loads. Cranes may be mobile or stationary. Energy for powering cranes mainly comes in the form of electricity. Similar to cranes, the energy for powering robots mainly comes in the form of electricity. Robotic trucks and carriers are able to move products along pre-planned paths. Robotic trucks are sometimes called automatic guided vehicles (AVGs).
The provision of adequate food, provision of raw materials of agro-industries and processing of agricultural produce require energy, which vary in form. Food production requires inputs such as fertilizer and pesticides, some of which are produced from oil and natural gas. It also requires human and animal labour and machines. Mechanical implements powered by fuel or electricity are immensely more efficient and productive than humans and animals.
Water is another essential agricultural input that requires energy. In developed countries, a major portion of electricity used in agriculture powers irrigation pumps. Agricultural produce processing also requires energy, whether for simple drying or for more complex extraction, cooking, refining and preserving. Milling and husking of grain crops consume substantial amount of energy. Beyond all these, agricultural produce and inputs require transportation facilities, and in some instances, refrigeration. The energy requirements in agriculture are mainly met using solar energy, fossil fuels (oil, coal and natural gas), fuel wood and electricity.
Most of the energy used in industry is used by the machines and processes, which make the products of industry. Industrial energy-consuming systems include boiler and other fired systems (furnace, kilns, incinerators, dryers), compressed air system, electric motors (for fans, blowers, pumps, conveyers, etc.) and lighting system. Energy is also used to heat or cool the buildings and to provide hot water and other facilities for workers. The energy used in industry comes in the form of fossil fuels (oil, coal and natural gas) and electricity. Energy is needed to make every single product, and is used at every stage of manufacture. Take for example, a product made from metal. The metal-bearing ore is first extracted from the ground using sophisticated machines that use energy. The ore is then transported – this also uses energy. Energy is also needed to melt and refine the ore, and again to machine it into its final form. The final product may then be packaged, which also uses energy.
The present population levels and city structures require highly sophisticated communication systems both for the supply of goods and services, and the maintenance of organisational cohesion. The maintenance of these systems requires a ready supply of suitable energy. Electrical energy is is the most common form of energy used and supplemented by chemical energy from batteries. Information processing, storage and retrieval also use a lot of energy in commerce.
Energy is required in households for space heating or cooling, water heating, cooking, lighting, ironing, and power appliances like fridge, washing machines, sound systems, TV, hair dryers, shavers, clocks, blenders, toasters, vacuum cleaners, sewing machines, etc. The energy may come from direct heating from the sun, electricity, burning of fossil fuels or fuel wood.
Fdonkor 09:53, 27 February 2007 (CET)