12 May 2011

Explain about the patterns of energy consumption in domestic, industrial, transportation and agricultural sectors.

Domestic Sector

It is the amount of energy that is spent on the different appliances used within housing. The amount of energy used per household varies widely depending on the standard of living of the country, climate, and the age and type of residence. In an average household in a temperate climate the yearly use of household energy can be composed as follows:

Average domestic energy consumption per household in temperature climates
12000 kW·h/yr (1400 watts)
3000 kW·h/yr   (340 watts)
1200 kW·h/yr   (140 watts)
1200 kW·h/yr   (140 watts)
Washing and drying
1000 kW·h/yr   (110 watts)
1000 kW·h/yr   (110 watts)
600 kW·h/yr     (70 watts)

 i) Heating & Cooling 

It takes a lot of energy to heat rooms in winter and cool them in summer. Half of the energy used in the average home is for heating and cooling rooms. The three fuels used most often for heating are natural gas, electricity, and heating oil. Today, In US, more than half the nation’s homes use natural gas for heating. 

The second leading fuel for home heating is electricity. Electricity also provides almost all of the energy used for air conditioning. The efficiency of heat pumps and air conditioners has increased more than 50 percent in the last 30 years. 

 Heating oil is the third leading fuel used for home heating. In 1973, the average home used 1,300 gallons of oil a year. Today, that figure is about 800 gallons, a significant decrease. New oil furnaces burn oil more cleanly and operate more efficiently. 

ii) Lighting 

Homes and commercial buildings also use energy for lighting. The average home spends 10 percent of its electric bill for lighting. Schools, stores, and businesses use about 38 percent of their electricity for lighting. Most commercial buildings use fluorescent lighting. It costs more to install, but it uses a lot less energy to produce the same amount of light. 

Most homes still use the type of light bulb invented by Thomas Edison over 100 years ago. These incandescent bulbs are not very efficient. Only about 10 percent of the electricity they consume is converted into light. The other 90 percent is converted to heat.

Compact fluorescent light bulbs (CFLs) can be used in light fixtures throughout homes. Many people think they cost too much to buy, but they actually cost less overall because they last longer and use less energy than incandescent bulbs.

iii) Appliances 

Over the last 100 years, appliances have changed the way we spend our time at home. Chores that used to take hours can now be done in minutes by using electricity instead of human energy. In 1990, Congress passed the National Appliance Energy Conservation Act, which requires appliances to meet strict energy efficiency standards. As a result of this Act, home appliances have become more energy efficient. Water heaters, refrigerators, clothes washers, and dryers all use much less energy today than they did 25 years ago.

iv) Appliance Efficiency Ratings 

When you buy an appliance, you should pay attention to the yellow Energy Guide label on every appliance. This label tells you the Energy Efficiency Rating (EER) of the appliance. The EER tells how much it costs to operate the appliance.

Industrial Sector

Today all countries are highly industrialized. We use a lot of energy. Today, the industrial sector uses 31 percent of the nation’s energy. Since 1973, the industrial sector has grown by two-thirds, but has used only 15 percent more energy to fuel that growth. Every industry uses energy, but six energy-intensive industries use most of the energy consumed by the industrial sector. 

i) Petroleum Refining 

Petroleum can’t be used as it comes out of the ground. It must be refined before it can be used. Oil refineries use a lot of energy to convert crude oil into gasoline, diesel fuel, heating oil, chemicals, and other products. Almost half of a refinery’s operating costs (43 percent) is for energy. Refineries today use about 25 percent less energy than they did in 1973. 

ii) Steel Manufacturing 

The steel industry uses energy to turn iron ore and scrap metal into steel. Hundreds of the products we use every day are made of steel. It is a very hard, durable metal and it must be heated to very high temperatures to manufacture it. Producing those high temperatures takes a lot of energy. The cost of energy in the steel industry is 15 to 20 percent of the total cost of making the steel. Most of this energy comes from coal, or electricity generated from coal. 

Since 1973, the steel industry has reduced its energy consumption by 45 percent per ton of steel. New technology has made steel stronger so that less steel is needed for many uses. For example, the Willis Tower, formerly the Sears Tower, in Chicago could be built today using 35 percent less steel. The use of recycled steel also saves energy. It requires 33 percent less energy to recycle steel than to make it from iron ore. Today, two-thirds of new steel is made from recycled scrap, making steel the nation’s leading recycled product. 

iii) Aluminum Manufacturing 

Aluminum is a very light-weight, versatile metal. We use aluminum to make soft drink cans, food wrap, car parts, and many other products. It takes huge amounts of electricity to make aluminum from bauxite, or aluminum ore. The cost of electricity is 30 percent of the cost of manufacturing aluminum. 

          Today, it takes 23 percent less electricity to produce a pound of aluminum than it did 30 years ago, mainly because of recycling. Using recycled aluminum requires about 95 percent less energy than converting bauxite into metal. 

iv) Paper Manufacturing 

          We uses enormous amounts of paper every day— newspapers, books, bags, and boxes are all made of paper. 

          Energy is used in every step of paper making. Energy is used to chop, grind, and cook the wood into pulp. More energy is used to roll and dry the pulp into paper. In 1973, the amount of energy needed to make one ream (500 sheets) of copy paper was equal to 3.7 gallons.

          Today, with advanced technologies, the energy used to make the same amount of paper would equal just two gallons of gasoline. 

          The paper and pulp industry uses 42 percent less energy today, mainly because of better technology. Many industries have lowered energy use by using recycled materials. In the paper and pulp industry, it is not cheaper to use recycled paper because it costs money to collect, sort, and process the waste paper. 

          Recycling has other benefits. It reduces the amount of paper in landfills and means fewer trees must be cut. 

v) Chemical Manufacturing 

          Chemicals are an important part of our lives. We use chemicals in our medicines, cleaning products, fertilizers and plastics, as well as in many of our foods.
          The chemical industry uses energy in two ways. It uses coal, oil, and natural gas to power the machinery to make the chemicals. It also uses petroleum and natural gas as major sources of hydrocarbons from which the chemicals are made. 

          New technology has made the chemical industry 60 percent more energy efficient than it was 30 years ago. 

vi) Cement Manufacturing 

          New roads and buildings are being built everywhere, every day. We use lots of concrete.
          Concrete is made from cement, water, and crushed stone. A lot of energy is used in making cement. The process requires extremely high temperatures—up to 3,500 degrees Fahrenheit. 

          Cement plants have reduced their energy consumption by one-third using innovative waste-to-energy programs. More than half of the cement plants in the U.S. now use some type of waste for fuel. These wastes, such as printing inks, dry cleaning fluids and used tires, have high energy content. For example, the energy content of one tire equals that of two gallons of gasoline. This industry is using energy that would otherwise be wasted in a landfill. 

Transportation sector

          The transportation sector uses twenty-seven percent of the energy supply to moving people and goods from one place to another. 

i) The Automobile 

          All peoples love automobiles. We love to drive them. We don’t want anyone telling us what kind of car to buy or how much to drive it. Automakers produce cars smaller and lighter. They built smaller and more efficient engines. 

          One reason for the changes was that the government passed laws requiring automobiles to get better gas mileage. With new technologies, cars now travel more miles on each gallon of gas. Today, passenger cars get an average of 30 miles per gallon. If automakers hadn’t made these changes, we would be using 30 percent more fuel than we do today. 

With the recent fluctuations in fuel prices, however, demand for these big vehicles has dropped, while demand for hybrids and other fuel efficient vehicles has increased. 

2) Commercial Transportation 

Passenger cars consume about two-thirds of the fuel we use for transportation. Commercial vehicles consume the rest. These vehicles—trains, trucks, buses, and planes—carry people and products all across this vast country. Commercial vehicles have also become more fuel efficient in the last 30 years. 

Trucks use more fuel than any other commercial vehicle. Almost all products are at some point transported by truck. Trucks are big and don’t get good gas mileage. They have diesel engines and can travel farther on a gallon of diesel fuel than they could on a gallon of gasoline. In the last thirty years, trucks have improved their gas mileage from 4.8 miles per gallon to about seven miles per gallon. 

Trains carry most of the freight between cities. In the last 30 years, trains have improved their fuel efficiency by 60 percent. Trains are lighter and stronger and new locomotives are more efficient. 

Airplanes move people and products all over the country. In 2008, more than 800 million passengers flew on planes. Airlines are twice as efficient today as they were 30 years ago. Fuel is one of the biggest operating costs for airlines. Making planes more energy efficient is very important to airlines. 

Mass Transit is public transportation for moving people on buses, trains, light rail, and subways. Today, there are about eight billion trips made on public transit systems. Most mass transit systems were designed to move people around cities or from suburbs to cities. Very few systems move people from suburb to suburb. 

Agricultural Sector

          Agriculture, as a production-oriented sector, requires energy as an important input to production. The energy consumed in agriculture consists of all direct and indirect energy used on the farm. Direct energy includes electricity, heating fuel and machinery fuel used in crop production, grain drying, animal and animal product production, poultry, transportation of farm products and personal energy use (for example, heating farmhouse and driving to town). Indirect energy consists of the energy consumed in the production, packaging and transport to the farm gate of fertilizers, pesticides, farm machinery and buildings.

* Agriculture is reliant on the timely availability of energy, but has been reducing its overall rate of energy consumption
* Energy’s share of agricultural production expenses varies widely by activity, production practice, and locality
* At the farm level, direct energy costs are a significant, albeit relatively small component of total production expenses in most activities and production processes
* When combined with indirect energy expenses, total energy costs can play a much larger role in farm net revenues, particularly for major field crop production
* Energy price changes have implications for agricultural choices of crop and activity mix, and cultivation methods, as well as irrigation and post-harvest strategies.

Energy Uses in Agricultural Production

Direct Use of Energy
Operating farm machinery and large trucks:
- field work (tractors, combines, mowers, balers, etc.)
- input purchase and deliveries (large trucks)
Diesel fuel
Operating small vehicles (cars and pickup trucks):
- farm management activities
Operating small equipment:
- Irrigation equipment
- Drying of grain or fruit
- Ginning cotton
- Curing tobacco
- Heating for frost protection in groves and orchards
- Crop flamers
- Heating/cooling of cattle barn, pig or poultry brooder,
greenhouse, stock tanks, etc.
- Animal waste treatment
- Standby generators

Diesel fuel
Natural Gas (NG)
LP Gas (LP)
Electricity (E)
General farm overhead
- Lighting for houses, sheds, and barns
- Power for farm household appliances
Custom operations
- Field work (e.g., combining)
- Drying
- Other

Indirect Use of Energy
- Nitrogen-based (NG is 75% to 90% of cost of prod.)
- Phosphate (NG is 15% to 30% of cost of prod.)
- Potash (NG is 15% of cost of prod.)
Natural Gas (NG)
Pesticides (insecticides, herbicides, fungicides)
Petroleum or NG