Energy is not monolithic. Most discussions of energy policy, however, treat energy as if it were one product, where a single solution would solve the world's energy needs. This misunderstanding leaves us with an obvious quandary: We're a long way from designing an airplane that can fly on electricity and we may never want to fly a nuclear airplane. Wind power is just not going to fly an airplane.
We need to analyze energy through several different concepts. Energy used in a home is very different from energy used in an automobile. Each energy use has its own requirements and each energy source has its own characteristics. Each energy need should be considered on its own, not merely lumped into the one-dimensional term "energy."
Dimensions to be considered include the requirements for each use of energy including portability, explosivity, and heat.
Use refers to the features of energy needed to produce a desired outcome.
Portability refers to the ease moving energy from one point to another.
Explosivity is energy converted per unit of time; like a bomb. Regardless of the temperature at which a fuel burns, an airplane requires an explosive fuel.
Heat is the temperature produced by the fuel; like a fire. A steel plant needs fuel that burns at a high temperature, rather than explosivity.
The difference between explosivity and heat is the time frame in which energy is released. An explosive substance releases energy instantaneously. A substance producing heat releases energy over a longer period of time. Petrol for instance will explode when sparked in an internal combustion engine. Coal, on the other hand, burns over time.
Another often overlooked and critical consideration is the difference between energy sources and energy conveyance.
Energy sources are the fossil fuels and renewable sources that generate energy.
Energy conveyors are the methods by which energy is moved from the source to its final use.
Energy Uses
Each use of energy is different. Energy uses in a home are primarily low to medium voltage electrical appliances, hot water heating, and heating for comfort. More and more frequently, alternating current is converted to low voltage direct current for use in electronic devices such as televisions and computers.
An office or commercial building is similar to a home. Energy used in a building requires no portability or explosivity and only needs to produce heat for water and comfort heating.
Energy used by an automobile, however, requires explosive power and extreme portability. Heat on the other hand is not necessary for operating an automobile. In fact, it is critical to remove heat from an automobile engine.
Heavy manufacturing, i.e. in a steel plant, requires no portability and generally no explosive power but extremely high heat.
Energy Sources
An energy source is the substance or fundamental force from which energy is derived. Oil, natural gas, coal, and uranium represent substances from which we produce energy. Wind, wave, and solar power are fundamental forces from which we derive energy.
Energy Conveyors
Energy conveyors are how we actually move energy from place to place as opposed to methods to conveyance fuel. Electricity is an energy conveyance method rather than a source.
Energy is produced by burning coal, for example, and that energy is transformed, conveyed, and used as electricity. In fact, oil, gas, coal, and nuclear fuel produce electricity in the same way. Each is used to heat water to make high pressure steam which turns a turbine connected to an electrical generator. Hydro power uses water pressure, or weight, to turn the turbine directly. Wind uses the blades of the wind turbine to turn an electrical generator directly.
Solar power can produce electricity in different ways. A photovoltaic cell makes electricity through subatomic stimulation of electrons. A solar tower uses mirrors to concentrate sunlight and heat water to make steam, similar to the way fossil fuels are used to create electricity.
Wave power can also be harnessed in different ways. One method is setting install a turbine in a river or on shore, using tides to turn a turbine. Another is to use the motion of the waves to move a magnetic or electrical coil to generate electricity.
Energy sources and energy conveyors sometimes intertwine. Coal can be used as an energy source to produce electricity, but it can also be used directly to create heat.
Wind is not a conveyor because we can only use the wind to create electricity which conveys the energy for use in our homes, buildings, and vehicles.
Hydrogen is not an energy source
Although hydrogen has been promoted as an energy source, it is important to understand that hydrogen can only be used for energy conveyance. Hydrogen is not an energy source by itself because it cannot be mined or captured; it must be produced using an energy source. Hydrogen generally exists as a component of a molecule in conjunction with other elements, most commonly in H(2)O for instance.
According the U.S. Department of Energy, 95 percent of hydrogen currently used is produced by the burning of natural gas. (
http://fossil.energy.gov/programs/fuels/hydrogen/currenttechnology.html). Best practices currently require at least five times the energy for production of each unit of hydrogen then the hydrogen will deliver when used. The cheapest method of production currently available would make hydrogen about four times as expensive as gasoline at the pump. Id.
A hydrogen fuel cell vehicle uses natural gas or some other energy source to produce hydrogen and the hydrogen for energy conveyance. This distinction between sources and conveyors is critical. The Bush administration promoted the "hydrogen revolution," but few people realized that the administration was referring to hydrogen produced by the burning of fossil fuels. Hydrogen produced thru wind, wave, or solar power, on the other hand would be a partial solution to our energy needs.
Ethanol would likely be considered to be a conveyor. The energy source is corn, sugar cane, or grass which is processed into a liquid that is carried and burned at the energy use. Again, the energy source is not the ethanol itself, but rather the sun, fertilizers, and power put into growing the crops.
Other critical issues concerning ethanol are land taken out of the production of food, forests cut down to make room for crops, and whether the energy produced by ethanol significantly outweighs the energy used to produce it.
We will need oil for a long time
It's true; we will need oil for a long time still. It's not that we need oil or petrol to fuel our cars, but we will need petroleum to produce aviation fuel. An airplane requires a fuel with extreme portability and high explosivity. We cannot fly an airplane on coal and we wouldn't want to fly a nuclear powered jet.
So, we need a more complex discussion of energy. We need to ask ourselves what we use energy for, what requirements each use has, and how we can best generate and convey energy for that particular purpose.
Uses of Energy |
Uses | Portability | Explosivity | Heat |
Transportation |
Automobiles | High | High | N/A |
Trucks | High | High | N/A |
Trains | Medium | High | N/A |
Airplanes | Extremely high | Extremely high | N/A |
Space travel | Unbelievably high | Unbelievably high | N/A |
Buildings |
Homes | None | Low | Low |
Large residential | None | Low | Low |
Commercial |
Offices | None | Mostly low to medium | Low |
Stores | None | Medium | Low |
Entertainment | None | Medium | Low |
Manufacturing |
Light | None | Medium | Low |
Heavy | None | Very High | High to very high |
Energy Sources |
Sources | Portability | Explosivity | Heat |
Fossil Fuels |
Oil | High | High | Extremely high |
Natural gas | High | High | Extremely high |
Coal | Very low | None | Extremely high |
Nuclear | None | Extremely high | Extremely high |
Renewables |
Wind | None | None | None |
Solar | None | None | None |
Hydro | None | None | None |
Wave | None | None | None |
Geothermal | None | None | Low |
Biomass | Low | Low | Medium |
Energy Transport |
Sources | Portability/Transmission | Explosivity | Heat |
Liquids/Gases/Solids |
Oil | High | High | Extremely high |
Natural gas | High | High | Extremely high |
Coal | Very low | Very low | Extremely high |
Hydrogen | High | Low | High |
Ethanol | High | High | High |
Electricity |
Direct Current | Medium/Low | Low | Low to medium |
Alternating Current | None/Very high | Low to high | Medium to very high |
No one solution exists. We will need certain levels of each energy source and conveyors in order to fuel our future. Only when we examine the sources, conveyors, and uses of energy as a diverse system can we plan for an energy future.
Contact Circle Law