




]]> (Gaia) GENERAL Sat, 18 Jun 2011 22:33:53 +0000
There Is No Energy Crisis, There is a Crisis of Ignorance There Is No Energy Crisis, There is a Crisis of Ignorance

]]> (Gaia) GENERAL Sat, 18 Jun 2011 22:30:15 +0000
What Is a Degree-Day?
Freezing winter weather or a long, sweltering summer — either one increases your utility bills. But how much of the rise in the cost is a result of the weather? You can find out by using a unit of measure called the "degree-day." A degree-day compares the outdoor temperature to a standard of 65°F; the more extreme the temperature, the higher the degree-day number and the more energy needed for space heating or cooling.

Hot days, which require the use of energy for cooling, are measured in cooling degree-days. On a day with a mean temperature of 80°F, for example, 15 cooling degree-days would be recorded. Cold days are measured in heating degree-days. For a day with a mean temperature of 40°F, 25 heating degree-days would be recorded. Two such cold days would result in a total of 50 heating degree-days for the two-day period.

The West North Central region normally requires more heating than other regions.

Map of heating degree days

Data for this figure

What Is Degree-Day Data Used For?

By studying degree-day patterns in your area, you can evaluate the increases or decreases in your heating or air-conditioning bills from year to year.

The West South Central region normally requires more cooling than other regions.

Map of cooling degree days

Data for this figure

Where Can I Find Degree-Day Data?

In some areas, degree-day information is published in the local newspapers, usually in the weather section. Degree-day information may also be available from your local utility and its public relations department. Some utility bills even show degree-days for each billing period.

The U.S. Energy Information Administration publishes regional averages for:

What Is Normal for Each Region?

The degree-day maps show the population-weighted degree-days that normally occur in each region of the United States.

]]> (Gaia) GENERAL Sun, 07 Mar 2010 02:42:13 +0000
Energy Units and Calculators Physical units reflect measures of distances, areas, volumes, heights, weights, mass, force, and energy. Different types of energy are measured by different physical units:
  • Barrels or gallons for petroleum
  • Cubic feet for natural gas
  • Tons for coal
  • Kilowatthours for electricity


How Big is a Barrel?

A confusing unit of measure is a barrel. A barrel's capacity is determined by who uses the term and what it contains.

For example:

1 barrel of Portland cement = 376 pounds
1 barrel of flour = 196 pounds
1 barrel of pork or fish = 200 pounds
A barrel may be called a "drum," but a drum usually holds 55 gallons

Units for Comparing Energy

Some popular units for comparing energy include British Thermal Units (Btu), barrels of oil equivalent, metric tons of oil equivalent, metric tons of coal equivalent, and terajoules.

In the United States, the Btu, a measure of heat energy, is the most commonly used unit for comparing fuels. Because energy used in different countries comes from different places, the Btu content of fuels varies slightly from country to country.

The Btu content of each fuel provided below and used in the energy calculator reflects the average energy content for fuels consumed in the United States.

Btu Content of Common Energy Units

  • 1 gallon of gasoline = 124,000 Btu (based on U.S. consumption, 2008)
  • 1 gallon of diesel fuel = 139,000 Btu
  • 1 gallon of heating oil = 139,000 Btu
  • 1 barrel of residual fuel oil = 6,287,000 Btu
  • 1 cubic foot of natural gas = 1,028 Btu (based on U.S. consumption, 2008)
  • 1 gallon of propane = 91,000 Btu
  • 1 short ton of coal = 19,988,000 Btu (based on U.S. consumption, 2008)
  • 1 kilowatthour of electricity = 3,412 Btu

Examples of Converting Different Energy Sources to Btu

Example 1:

You have a natural gas furnace in your home that used 81,300 cubic feet of natural gas for heating last winter. Your neighbor has an oil furnace that used 584 gallons of heating oil last winter. To determine which home used more energy for heating, you can convert the natural gas and heating oil consumption figures into Btu, as follows:

Natural Gas: 81,300 cubic feet (your house)


1,028 Btu per cubic foot

= 83,576,400 Btu

Heating Oil: 584 gallons (neighbor's house)


139,000 Btu per gallon

= 81,176,000 Btu

Answer: You used more energy to heat your house!

Example 2:

You work for an electric power company. Your company’s power generators can run on one of two fuels: natural gas or residual fuel oil. Your job is to switch fuels when the cost of the fuel you are currently using becomes more expensive than the other fuel. This will keep costs down for you and your electricity customers. Your company’s generators are currently using residual fuel oil, but fuel oil prices have been going up much faster than natural gas prices. Based on the fuel costs below, you need to decide if it is time to switch to natural gas:

Natural Gas:

$7.30 per thousand cubic feet


1.028 million Btu per thousand cubic feet =

$7.10 per million Btu

Residual fuel oil:

$57.75 per barrel


6.287 million Btu per barrel =

$9.19 per million Btu


What Is a Btu?

A "British thermal unit" (Btu) is a measure of the heat content of fuels. It is the quantity of heat required to raise the temperature of 1 pound of liquid water by 1°F at the temperature that water has its greatest density (approximately 39°F).

Why Do We Use Btu?

One practical way to compare different fuels is to convert physical units of measure (such as weight or volume) into a common unit of measurement based on the energy content of each fuel.The British thermal unit (Btu) is a widely used measure of energy content.

Using Btu for Comparing Home Heating Fuels

How can you compare home heating fuel prices? You must compare the cost per heating value (Btu) of each fuel.

Using Btu for Comparing Electricity Generation Fuels

Suppose you have been assigned the responsibility of purchasing fuel for a large electric utility company. You need to keep costs down for you and your electricity customers. Which fuel would you choose to generate electricity — coal, oil, or natural gas? In 2008, average prices of fuel delivered to electric power plants were:

  • $41.14 per short ton of coal
  • $64.89 per 42-gallon barrel of oil
  • $9.26 per thousand cubic feet of natural gas

The prices of each fuel look quite different, but you can compare the prices of their energy content by first converting to Btu.

A short ton of coal contains about 21 million Btu, a barrel of oil contains about 6 million Btu, and a thousand cubic feet (Tcf) of natural gas contains about 1 million Btu. After dividing price by energy content, you can see which fuel is least expensive:

Price Btu (Energy Content) $/Million Btu
Coal $41.14 per ton 21 million per short ton $1.96
Oil $64.89 per barrel 6 million per barrel $10.82
Natural Gas $9.26 per Tcf 1 million per Tcf $9.26

So coal is actually the least expensive fuel on a price-per-energy content basis.

Of course, cost is not the only factor to consider when selecting a fuel. Environmental restrictions and equipment costs are some of the other factors that should be taken into account.

Btu Quick Facts

A single Btu is insignificant in terms of the energy use in a single household or in the Nation's energy consumption. In 2008, the United States used over 99 quadrillion (written out, 1 quadrillion is a 1 followed by 15 zeros) Btu of energy.

One quadrillion Btu is a very large amount of energy:

  • One Btu is approximately equal to the energy released in the burning of a wood match.
  • One million Btu equals about 8 gallons of motor gasoline.
  • One billion Btu equals all the electricity that 300 households consume in one month.
  • One trillion Btu is equal to 500 100-ton railroad cars of coal.
  • One quadrillion Btu is equal to 172 million barrels of crude oil.
]]> (Gaia) GENERAL Sun, 07 Mar 2010 02:10:21 +0000
Laws of Energy
Energy Is Neither Created Nor Destroyed

image of energy transformation from one form to anotherTo scientists, "conservation of energy" does not mean saving energy. Instead, the law of conservation of energy says that energy is neither created nor destroyed. When we use energy, it doesn't disappear. We change it from one form of energy into another.

A car engine burns gasoline, converting the chemical energy in gasoline into mechanical energy. Solar cells change radiant energy into electrical energy. Energy changes form, but the total amount of energy in the universe stays the same.

Converting One Form of Energy Into Another

"Energy efficiency" is the amount of useful energy you get from any type of system. A perfectly energy-efficient machine would change all the energy put in it into useful work. In reality, converting one form of energy into another form always involves a loss of useable energy.

In fact, most energy transformations are not very efficient. The human body is a good example. Your body is like a machine, and the fuel for your machine is food. Food gives you the energy to move, breathe, and think. But your body isn't very efficient at converting food into useful work. Your body is less than 5% efficient most of the time. The rest of the energy is lost as heat.

]]> (Gaia) GENERAL Sun, 07 Mar 2010 02:06:17 +0000
Sources of Energy
We use many different energy sources to do work. Energy sources are classified into two groups — renewable and nonrenewable. Renewable and nonrenewable energy can be converted into secondary energy sources like electricity and hydrogen.

Chart of Energy Consumption by Source, 2008
Source: U.S. Energy Information Administration, Annual Energy Review (2008)


Most of Our Energy Is Nonrenewable

In the United States, most of our energy comes from nonrenewable energy sources. Coal, petroleum, natural gas, propane, and uranium are nonrenewable energy sources. They are used to make electricity, to heat our homes, to move our cars, and to manufacture all kinds of products.

These energy sources are called nonrenewable because their supplies are limited. Petroleum, for example, was formed millions of years ago from the remains of ancient sea plants and animals. We can't make more petroleum in a short time.

Use of Renewable Energy Is Growing

Renewable energy sources include biomass, geothermal energy, hydropower, solar energy, and wind energy. They are called renewable energy sources because they are replenished in a short time. Day after day, the sun shines, the wind blows, and the rivers flow. We use renewable energy sources mainly to make electricity.

How Are Secondary Sources of Energy Different?

Electricity and hydrogen are different from the other energy sources because they are secondary sources of energy. Secondary sources of energy — energy carriers — are used to store, move, and deliver energy in easily useable form. We have to use another energy source to make electricity or hydrogen. In the United States, coal is the number one energy source for generating electricity.

Today the cheapest way to get hydrogen is by separating it from natural gas, a nonrenewable energy source. Hydrogen can also be separated from water and from renewables, but hydrogen made from these sources is currently too expensive to compete with other fuels. Scientists are working on ways to make hydrogen from water and renewables more affordable.

]]> (Gaia) GENERAL Sun, 07 Mar 2010 00:33:58 +0000
Forms of Energy

Potential Energy


Kinetic Energy











]]> (Gaia) GENERAL Sun, 07 Mar 2010 00:24:27 +0000
What is Energy?
Energy makes change possible. We use it to do things for us. It moves cars along the road and boats over the water. It bakes a cake in the oven and keeps ice frozen in the freezer. It plays our favorite songs on the radio and lights our homes. Energy is needed for our bodies to grow and it allows our minds to think.


Energy comes in different forms:

  • Heat (thermal)
  • Light (radiant)
  • Motion (kinetic)
  • Electrical
  • Chemical
  • Nuclear energy
  • Gravitational


Energy is in everything. We use energy for everything we do, from making a jump shot to baking cookies to sending astronauts into space.

There are two types of energy:

  • Stored (potential) energy
  • Working (kinetic) energy


For example, the food you eat contains chemical energy, and your body stores this energy until you use it when you work or play.

Energy Sources Can be Categorized As Renewable or Nonrenewable

When we use electricity in our home, the electrical power was probably generated by burning coal, by a nuclear reaction, or by a hydroelectric plant at a dam. Therefore, coal, nuclear and hydro are called energy sources. When we fill up a gas tank, the source might be petroleum or ethanol made by growing and processing corn.


Renewable Energy

Renewable energy sources include:

  • Solar energy from the sun, which can be turned into electricity and heat
  • Wind
  • Geothermal energy from heat inside the Earth
  • Biomass from plants, which includes firewood from trees, ethanol from corn, and biodiesel from vegetable oil
  • Hydropower from hydroturbines at a dam
The Role of Renewable Energy Consumption in the Nation's Energy Supply: Petroleum 37%, Natural Gas 24%, Coal 23%, Nuclear Electric Power 9%, Renewable Energy 7%. Renewable energy breakdown: Solar 1%, Geothermal 5%, Wind 7%, Hydropower 34%, Biomass 53%

Nonrenewable Energy

We get most of our energy from nonrenewable energy sources, which include the fossil fuels — oil, natural gas, and coal. They're called fossil fuels because they were formed over millions and millions of years by the action of heat from the Earth's core and pressure from rock and soil on the remains (or "fossils") of dead plants and creatures like microscopic diatoms. Another nonrenewable energy source is the element uranium, whose atoms we split (through a process called nuclear fission) to create heat and ultimately electricity.

We use renewable and nonrenewable energy sources to generate the electricity we need for our homes, businesses, schools, and factories. Electricity "energizes" our computers, lights, refrigerators, washing machines, and air conditioners, to name only a few uses.

Most of the gasoline used in our cars and motorcycles and the diesel fuel used in our trucks are made from petroleum oil, a nonrenewable resource. Natural gas, used to heat homes, dry clothes, and cook food, is nonrenewable. The propane that fuels our outdoor grills made from oil and natural gas, both nonrenewable.

The chart above shows what energy sources the United States uses. Nonrenewable energy sources account for 93% of all energy used in the Nation. Biomass, the largest renewable source, accounts for over half of of all renewable energy and 3.7% of total energy consumption. (Note: 53% of 7% is 3.7%.)

]]> (Gaia) GENERAL Sat, 06 Mar 2010 23:54:39 +0000
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