Until the invention of mechanical power, humans had been relying on energy derived from muscles and natural forces such as horses and wind for a long time. During the period between 1770 and 1870, three types of engine were invented and have gained universal acceptance: the steam engine, the electric motor, and the internal combustion engine. All three require fuels to work, but only the third one requires oil to be burned inside the engine, producing an undesirable gaseous exhaust.
Despite its limitations, the internal combustion engine has transformed the world to the greatest extent mainly due to two reasons: easily portable liquid fuel, and the support of the large oil industry. In recent decades, four major handicaps have developed: rising oil prices, dwindling oil supply, increasing environmental pollution, and climate change due to burning fossil fuels. Thus, the search for alternative energy to replace fossil fuels has begun in earnest.
The search effort revolves around what kinds of fuel to use to produce electricity or steam. If internal combustion is taken out of the equation, we still have to rely on the mechanical power of the electric motor and the steam engine. Both are flexible with fuel and produce no undesirable exhausts. Regarding power delivery, both engines are comparable to internal combustion as evidenced by their employ in the propulsion of ships, locomotives, and autos, but not airplanes yet.
An alternative to fossil fuels must fulfill the following five conditions to be viable: lower price, less pollution, renewable, portable, and infrastructure support. Let’s examine the handicaps and promises of some energy alternatives already existing:
Nuclear fission has been used for decades to generate electricity. The nuclear reactor creates enormous heat to boil water to make steam that drives the turbine to generate electricity. Unfortunately, nuclear fission produces nuclear wastes, a big handicap raising alarms about health and safety. Nevertheless, some countries especially France, Belgium, Switzerland, Korea and Japan have developed quite a significant nuclear energy capacity. In addition, the US Navy employs small nuclear reactors to power its aircraft carriers, submarines and other ships. What about nuclear fusion using hydrogen? Fusion requires very high temperature and pressure like the conditions on the sun. Perhaps cold fusion will work but it’s only in the research stage.
Biomass refers to anything that can be burned to create energy. This includes wastes, cooking oil, sugar cane, corn, ethanol, biodiesel, switchgrass, and so on. It is renewable but still requires burning that will produce carbon dioxide and other undesirable gases. The purpose of biomass is to replace some oil just to relieve its four major handicaps mentioned earlier. Corn for fuel is really a bad idea because it forces direct competition with food. Do you really want to choose between eating and driving? Besides, corn requires chemical fertilizers to grow in modern farming practice. Chemical fertilizers are derived from petroleum, thus reversing us back to square one.
Hydro technology has been working for decades. It depends exclusively on geography and water flow. Its environmental impacts will take many years to become evident. Whether it is renewable is hard to say. What if climate change causes insufficient rainfall and snow? Where will the water come from? We cannot dam every river or lake just to construct a hydro project without taking into account the impacts on people and the environment.
Geothermal energy is strictly location-dependent. This limits its possibilities. Iceland is one of the few countries where geothermal has widespread applications.
Wind power depends on geography like hydro but is more flexible. Wind farms can be built offshore or in scantily populated areas. Wind is always renewable except varying from day to day. Battery can solve this problem by storing the electricity generated during windy days for later use. One unique aspect is that wind power is scalable. That means it can be scaled down to serve one household, or scaled up to serve a large community. Wind power has grown more popular recently, rising to about 5% of total electricity generated in California for instance. This is low compared with Denmark, a leading pioneer in wind, which has achieved the world’s highest rate of 20%.
This leaves solar energy as the final viable candidate. In this sector, the promises overshadow the handicaps as illustrated below:
Sunlight is free and will last for another 5 billion years before the sun finally burns out. Despite available for part of the day, sunlight is much more consistent than wind. Batteries can solve this problem by storing the electricity generated on sunny days for later use.
Compared with wind, solar is even more scalable and flexible. Solar energy can be installed to serve a home, a neighborhood, or a big city. Rooftops provide the best stationary place for installation besides other open spaces. Solar can be installed on movable objects too, such as ships, trains and cars, even on hand-held electronic devices. A far-fetched idea being studied is to build large solar farms in outer space free from clouds and dust. The electricity generated would be beamed back to earth using microwaves.
Solar energy capitalizes on the advantage of a distributed system that enables the individual to perform independent work. If your home has solar installation, you effectively become electricity independent as both a generator and consumer. You don’t even need a transmission line for supply. Imagine this benefit to be extended to millions of households in poor countries where transmission infrastructure is lacking or unreliable. In developed countries with well established transmission lines, you can feed into the line with your surplus solar electricity for sale to the utility company. In case you drive a plug-in hybrid or electric car, you will save on your gasoline bills by recharging your vehicle at home.
Solar panels are mostly made of silicon. Its main purpose is to capture as much sunlight as possible. The efficiency depends on how the solar cells are made and how densely they are packaged on the panel. It’s more or less like building a computer chip. New technology has reduced the price of solar panels by half in recent years. Further price drops are expected as technology improves. Furthermore, the efficiency of solar panels will also improve from the current rate of 20%.
Solar panel is not the only product for capturing sunlight. Solar paints, glass, adhesive papers are being developed for the external surfaces of buildings, ships, trains, and even cars to make them independent electricity generators. This will greatly increase the possibility of solar electricity for the mass market when the price comes down low enough.
In conclusion, solar power presents the greatest potential among all forms of alternative energy. The only handicap is the initial capital cost. In recent years, the cost has been coming down drastically due to technological advance. Solar technology will continue to drive down the cost of electricity generation and storage; and drive up the efficiency of sunlight capturing. Solar energy is not a dream for the distant future. It is happening right now and waiting for commercialization to serve the mass market.
For an insightful review on energy, please read “The Quest” by Daniel Yergin, 2011.