Energy is a critical component of your lives and economy as a whole. You use energy in virtually every endeavor. Humans have evolved in step with the energy consumption. Human populations, quality of life, and life expectancy have increased as energy sources have become more sophisticated.
Historical trends of energy use
Early man couldn’t even light a fire. Upon the advent of fire, humans could warm themselves and cook their food. This began the consistent push toward bigger and better cultural and material gains, and it lead to healthier, happier lives.
Throughout time, the human population remained steady for the first 1,500 years and then began a steep, consistent climb. The increase is due largely to the availability of versatile, convenient energy. As controlled, or usable, energy became more prevalent, the population expansion accelerated.
As the human population grows, the total consumption of energy grows even faster. We humans seek comfort and consistency in our lives. Energy provides this, and so humans seek energy.
Over the last century, humankind experienced an unprecedented expansion of industrialization. Industrialization is a global phenomenon so energy resources are being consumed at an unprecedented rate the world over.
Energy is not running out, nor will it ever run out. The problem is not that less energy resources are available, but that of political and environmental consequences of the current energy consumption.
Sources of Energy
Every energy source has pros and cons, and trying to decide how best to provide the power an economy needs is a complex problem. To make sure that resources last, humans need to focus on alternative, renewable, and sustainable energy sources. Energy sources that fail to meet these criteria could eventually be depleted and thus cease to exist.
But what, exactly, do the words alternative, renewable, and sustainable mean? Alternative forms of energy are those that don’t include fossil fuels or carbon-combustible products. Renewable forms of energy constantly replenish themselves with little or no human effort. The benefits of renewables are that they replenish themselves and so relieve society of its reliance on dwindling, finite supplies.
Sustainable forms of energy are not only renewable, but they also have the ability to keep the planet Earth’s ecosystem up and running in perpetuity. The basic notion behind sustainable energy sources is that by their use, society is not compromising future generations’ health and well-being.
Solar power uses sunshine to create both heat and electricity, as well as passive heating and cooling effects in buildings. Large scale solar farms can provide entire communities with enough electrical and heating power to make the communities self-sufficient.
Nuclear power harnesses the tremendous energies from both the splitting and fusing of atoms.
Wind power derives from windmills placed in locations with a lot of wind.
Hydro power comes from dams which provide high pressure water flows that spin turbines, thereby creating electricity. It can be exploited on both a macro level and on the micro level.
Geothermal power takes heat from the earth and redistributes it into a building, or uses the heat to generate electrical power. It is available in tremendous quantities, but it is difficult to extract and takes a lot of capital equipment.
These materials are either burned in their raw form, or processed into liquid fuels or solid fuels.
Hydrogen fuel cells
Hydrogen fuel cells combine oxygen and hydrogen to produce water and electrical energy.
Electric vehicles use only electricity to power them. The electricity comes from batteries which are getting better and all-electric vehicles are now becoming economically competitive with conventional vehicles.
Bio fuels are made of biomass products such as corn.
Combustion vs. Non-Combustion
The majority of energy sources produce power through combustion processes (burning) that require a burn chamber, oxygen, and exhaustion capacities. From ancient times, humans have burned wood for fires, and the process was simple: Pile some wood and light it on fire. Modern combustion processes are engineered to be more efficient but the combustion processes, regardless of how efficient they are, are pollution sources.
Non-combustion processes, such as solar power and nuclear, don’t exhaust pollutants the same way that combustion processes do, but they have their own problems. For instance, solar photovoltaic (PV) panels require a lot of energy to manufacture, and most of this energy comes from electrical power which mostly comes from coal combustion. So while solar is pollution free in its on-site implementation, it entails a lot of pollution in its manufacture.
Other non-combustion energy sources such as wind and hydro power also require a great deal of energy to manufacture the capital equipment needed to make things work.
Every energy production plant, whether solar or a wood stove, needs raw materials. In the case of solar, the raw materials are free. In the case of a nuclear power plant, the raw materials are uranium rods, which must be refined and manufactured. In fact, the total cost of an energy process has less and less to do with the raw fuels. Capital equipment is expensive, and is usually the most influential component in a cost analysis equation.
Energy vs. Power
Energy is the total amount of effort or work it takes to accomplish a certain task. The monthly electricity utility bill is calculated in units of energy. When you pay your utility bill, you pay for energy, not power. In the international system (SI), a unit of energy is a joule.
Power is the speed with which energy is being expended to achieve a task. More power means the task is completed more quickly. When your electric meter spins, it is measuring power - the faster the meter spins, the more power you are using. Power is calculated by dividing energy by time.
The amount of energy that is contained in a unit of fuel (either weight or volume) is called the energy density. This is the amount of potential energy available in a given weight or volume of that fuel. Energy density determines how large a storage device is needed or how heavy a fuel will be in that storage device.
Efficiency is important in every energy process because it describes how much waste is being generated, in relation to the usable work that is being achieved.
Energy efficiency is simply the ratio of the useful work obtained from a process, by the raw power taken to achieve that process. Fuel efficiency in a car means the amount of kilometers that can be driven on a litre of petrol.
Operating efficiency is the efficiency of all the individual parts that comprise a whole. The operating efficiency is the value that has the most meaning because it takes into account all the things that can impact efficiency endeavors.
Cost efficiency is the cost of accomplishing a task divided by the amount of work that is done. This may be the most important efficiency measurement, as it determines how much it will cost to perform an energy process. With some fuels, even though the energy efficiency is high, the cost of the fuel is also high, so the cost efficiency may not be that good.
Pollution efficiency is the amount of work performed by a process divided by the amount of pollution generated by that process. Pollution efficiency, more than cost efficiency, is the most compelling argument in favor of alternative energy sources. With the economic infrastructure of fossil fuels, most alternative energy schemes are less cost efficient than fossil fuels, but the pollution efficiencies are much better.
Fundamental Laws Governing Energy Consumption
There are a number of basic fundamentals to all energy processes.
First law of thermodynamics: All energy consuming processes follow the first law of thermodynamics, which states that energy can neither be created nor destroyed. It can only change forms. We consume energy, but what we’re really doing is using energy in one form and converting that into other forms.
Second law of thermodynamics: The second law of thermodynamics states that disorder of any closed system can only increase which means that waste is unavoidable. The physics term for disorder is entropy. This implies a limit to how efficient we can make energy consumption processes.
Carnot’s law: At the turn of the century, steam engines were the predominant form of energy generation in our economy. The fact that steam engines required a lot of wood and water necessitated an efficiency analysis to find ways to lower costs while producing the same power levels.
As a consequence, a French engineer named Henri Carnot came up with a very important law which governs all combustion machines. Carnot’s law states that the maximum efficiency of any thermal energy process is determined by the difference in temperature between the combustion chamber and the exhaust environment where the waste is channeled. According to Carnot's law, it is the temperature difference that matters, not the temperature of the actual combustion process.
Coal fired power plants burn raw coal to boil water, which is used to turn huge turbines that create electricity. As per Carnot’s law, the hotter the coal is burned in relationship to the exhaust temperature the more efficient the plant operation will be.
All atoms have electrons, which have negative charges. When the electrons can break free, or detach, from their atoms and move through a substance, whether solid, liquid, or gas, you get electricity. How freely electrons move depends on how easily they can break away from their constituent atoms.
In materials like cotton, wood, plastic, and glass, the electrons are stuck; they can’t move around because they are captured by the atom that they belong to. These materials are insulators. In metals, on the other hand, the electrons are only slightly held to their host atoms and are able to move around. Because these materials enable the flow of electricity, they’re called conductors.
Some materials, like semiconductors, which are at the heart of all electronics devices, have properties that are somewhere between metals and insulators. The electrons can flow, but only under special conditions.
The electrons flow through a conductor if something spurs their movement. That something is a voltage. When a voltage, or electromotive force, is applied to a material, the electrons flow depending on the amount of resistance the material has.
Resistance is just a measure of how easily the electrical charge flows through a substance. Metals have low resistances, whereas insulators feature very high resistances. Resistance causes inefficiency. When the resistance of a material is very high, it takes a lot of energy to move the electrons through that material.
Producing electrical power efficiently and safely
The challenge power plants face in making the power they produce available to customers is how to maximize efficiency and at the same time control the voltage so that it can be used with some degree of safety.
As the power travels through the transmission wires, the power dissipates. One way to reduce the power dissipation is to get the current that travels through the lines as low as possible. Because electrical power is equal to voltage times current (P = VI), it is possible to raise the voltage and reduce the current and still end up with the same amount of power. In reducing the current, the line losses are reduced as is the amount of power wasted in the transmission process. Therefore, it is very desirable to use extremely high voltages on transmission lines.