Energy Sources

Energy Sources used in the US

Past to present Interesting to note, the TOTAL energy used is an exponential graph. Not only is the population increasing, but the amount of energy each person needs is increasing at an exponential rate. Pre-industrial revolution, the main source of energy was wood. After that, we start into the fossil fuels. Coal, then petroleum and natural gas.

Total Energy in the US in 2006

Total to generate electricity in 2006

Fossil Fuels Fossils fuels are a very convenient form of concentrated energy. Major fossil fuels used today are petroleum, natural gas and coal. Petroleum can be separated into gasoline, kerosene, and diesel fuel. The current deposits were formed when plants and animals were buried about 500 million years ago. These plants and animals took CO 2 from the atmosphere and energy from the sun 500 million years ago and stored it.

Petroleum Plants and animals are made of high energy compounds. Normally this energy is released when it decomposes, digests or is burned, but these were shut off from the world when they were buried. So it sat there stored from millions of years. The pressure over time concentrated the energy source. People have discovered several uses for these concentrated stored energy sources.

Oil Producing Countries US produces the third most oil behind Russia and Saudi Arabia.

Oil Reserves Although the US produces a lot of oil, it also uses more than it makes. The United States also imports oil to meet its demand. At some point, the reserves in the world will run out. Coal is still plentiful in the United States.

Greenhouse Effect ~Trapping of heat energy on the planet by certain gases The major greenhouse gases are carbon dioxide, water vapor and methane. Without these gases we would die because we would freeze to death at night. The moon is the same distance from the sun and -170 o C at night. With too much of these gases, our planet will heat up. The planet heating up is called global warming.

Greenhouse Effect Visible light energy comes to the Earth from the sun. This light passes right through the atmosphere unaffected. It then heats up the ground. Objects on Earth give off heat as infrared rays at the temperatures they are heated to. These rays go out from the ground. Greenhouse gases stop the infrared rays from escaping easily, and reflect many of them back so more heat energy is trapped on the planet.

The problem We use the ancient energy source (sun energy in ancient plants and animals), by burning it. When we do this it releases the carbon dioxide that has been out of our atmosphere for millions of years. Try and find Industrial Revolution on the graph

So What! Carbon dioxide is a green house gas. Increased levels of CO 2 in the atmosphere cause the temperature of the planet to rise Increased levels of CO 2 in the atmosphere cause the temperature of the planet to rise

I like it warm… This won’t actually make every area warmer… or this area tropical. The global average will be a few degrees warmer. You would still have cold days. Heat powers wind, weather systems, ocean currents etc. This will cause a global Climate Change. Some areas could get colder from this climate change, other areas could get warmer, but see higher snow falls.

How much will the planet heat up? only a few degrees (we won’t burn to death) But this could cause changes that can be very expensive and damaging. You could expect flooding of coastal areas and massive losses of crops, and increase in hurricanes… and lots of things we didn’t expect. A big concern is the unexpected. There are too many variables to be absolutely sure what will happen if the planet heats up.

Isn’t there disagreement on this? There is disagreement on how much the planet will increase in temperature, not that it is increasing. The planet has already slightly increased in temperature. There is disagreement on what the new climates will actually be. Certain areas are likely to benefit from a climate change, while others will be devastated. There is disagreement on which areas are which.

Hydrogen Hydrogen can be an excellent fuel source. H 2 + ½ O 2  H 2 O  H o = -286 kJ/mol H 2 + ½ O 2  H 2 O  H o = -286 kJ/mol If you remember from a previous example, hydrogen has 2.5x the heat of combustion as natural gas. Plus, the product is water. Although that is a greenhouse gas as a vapor, it will condense becoming harmless.

Hydrogen powered There are hydrogen powered cars, buses, even homes. You can convert any car to be hydrogen powered.

Big Problem There are NO hydrogen reserves on the planet! Hydrogen is plentiful in water, but… State function, law of conservation of energy There can be no net gain of energy by separating water into hydrogen and then recombining it. There will, however, be a loss of useful energy as heat in the process.

Still useful Hydrogen can be useful as a method of storing or transporting energy. For example, if you are using a renewable source of energy (like a wind mill, solar cell, or hydroelectric plant) to produce the hydrogen. Fuel cell cars produce their own hydrogen from water. They do so by recovering energy where it can be in the car, and by being plugged in.

Biomass Fuel Ethanol is one fuel with potential to supplement or even replace gasoline Ethanol can be mixed with gasoline, or used to run a car by itself. Current gasoline has 10% ethanol in it, E85 is a fuel that is 85% ethanol and 15% gasoline.

Combustion of ethanol C 2 H 5 OH+3 O 2  3 H 2 O+2 CO 2  H o = kJ You would need a bigger tank, but it can work. They have been running cars off of “moonshine” (ethanol) for years. The energy from this combustion is about half the energy per gram as gasoline.

To make ethanol You need a source of sugar. Corn, sugar cane, or any plant that produces sugar works. Then allow yeast to ferment the sugar. This is a spontaneous natural process. It won’t take energy from humans to happen. It is actually capturing the Sun’s energy.

Greenhouse gas… Carbon dioxide is produced from the combustion. However, the carbon dioxide was pulled out of the atmosphere in the production of sugar by the plant. The carbon dioxide concentration cannot increase in our atmosphere. There is not new carbon.

Methanol Methanol, an alcohol similar to ethanol, has been used in race cars for many years. It also has a possibility of powering cars and motors of all types.

Problems Growing enough sugar to make this feasible on global scale isn’t possible currently. Better methods for growing and breaking down cellulose to sugars could change that in the future.

Biodiesel Biodiesel is a fuel made by esterifying the fatty acids found in vegetable oil. Biodiesel works very similarly to regular diesel. Little modifications need to be made to an engine to run off pure biodiesel. It is also runs in blends, like ethanol.

Production This can be produced from used vegetable oil from restaurants. It is cheaper using this method because the oil is “free”. It is still expensive to produce. At the moment there is plenty of unused oil. However, there is not enough used to satisfy a larger demand. It becomes significantly more expensive if the oil is produced and purchased.