Hydro
The Evanger hydro plant in Norway is an example of the worlds leading-most transition to clean energy. Built inside a mountain with natural water flow from lakes above, a 20 mile network of pipes carries water to run the generators in the plant. These generators run at 500 rpms with the help of flow rates at 5,000 gallons per second. This is enough energy to provide 99% of Norway's total power usage by water, and is nearly emission-free.
Coal
Coal is extracted by large-scale mining operations that involve massive machinery and large areas of coal-producing land. At the Bel-air mine in Guinea, the topsoil excavated as the mine gradually moves is replaced on top of the back-filled location. The elevation is dramatically lower, however, as the material that is removed from the mine (coal) is the equivalent of 3 Panama canals per year. This puts the filled-in landscape behind the mine at least 100 feet below the surrounding landscape, effectively creating a trench. Coal is not a clean fuel source, either by its extraction or its use, but it currently provides roughly 50% of the energy in the U.S.
Oil
Oil is extracted by various methods, both on land and at sea. It is used in many things we tend to take for granted, which only increases the dependence on a non-renewable, pollution-causing limited resource. The oil is extracted mainly from below the sea floor by massive oil well platforms, on-shore drilling operations, and oil sands. The oil is transported by almost every major method of transportation including train, truck, and ship. The largest ships carry 750,000 barrels of oil per day, which is the equivalent of about 45 minutes of U.S. consumption. For even more perspective, the world uses one of these tankers of oil every 13 minutes. With 4 times the energy density of hydrogen, oil will be very difficult to replace with renewable energy sources in the future.
Bio fuels
Bio fuels have become more popular in recent years to reduce the dependence on oil, especially in the transportation sector. The U.S. has been the leading producer of bio fuels for the last 30 years, growing mainly corn and soybeans for the purpose. Diesel engines are especially easy to convert to bio fuels, and are popular for use in mass transit systems in larger cities. Unfortunately, they have a large carbon footprint thanks to the space needed to produce them, and the amount of waste in the production. For example, the only part of a corn plant that is able to be used for bio fuels is the corn kernels themselves, leaving the rest of the plant, and the energy and water that has gone into growing it, to waste.
In Louisiana, biologists have been able to grow sorghum to 18 foot heights and break down the cellulose to produce ethanol. This practice, along with other instances such as switchgrass production in "marginal land" in New York, means that the entire plant can be used in the production of ethanol. Unfortunately, the problem of the extreme amount of land needed for production will always remain the problem with bio fuel production.
Natural Gas
Natural Gas is extracted from the earth, and burns with very low emissions. It is said to be a very clean fuel which costs less than diesel. Compressed natural gas, or CNG, is used in mass transit systems similar to bio fuel use. It can also be used in the energy grids to supplement solar and wind systems. In order to compress the natural gas, compressors must be used. Specialty filling stations are in place in some of the larger cities with CNG bus systems, but the technology is not readily available for mass use.
One major concern on the extraction side of natural gas is contamination from fracking. Fracking is the practice of drilling into a productive natural gas area and fracturing the containment rock to increase total surface area. Heated water is then pumped into the fractures to release the material from the rock. Anti-corrosives and other chemicals are used in large-scale fracking operations. In the mid western U.S., many residents have complained about methane emissions from their individual wells, and ignitable tap water. Accusations of dangerous chemical use from the fracking process have been largely denied by major natural gas producers, though they admit to some contamination instances fro localized waste water risks on the surface. Studies to address the resident's concerns have yet to be performed.
Geothermal
Geothermal energy utilizes the heat generated within volcanic zones. Wells are drilled, and water is injected into the system to heat, returning to the surface in the form of steam. The steam is captured to run turbines, which produce electricity. The steam is collected and condensed into liquid, then re-injected into the geothermal system. There are no chemicals used in geothermal energy. Though this energy type produces less overall usable wattage than solar energy, the power supply is a consistent and uninterrupted source of power.
Solar
Solar power involves arrays of photo voltaic cells arranged in a panel to increase surface area, capturing direct sunlight throughout the day. Some solar arrays are affixed to the rooftops of homes, while larger arrays are mounted on motorized shafts that move to follow the sun, providing constant power during daylight hours. Smaller-scale installations also include parking lot covers, utilizing the available space above parking spaces to generate energy for the adjacent buildings. The heat produced by the panels creates steam to turn generators. The solar panels are only operational during daylight hours, as the energy cannot be stored. The heat generated by the panels can be stored though, and can provide the necessary steam to continue generator operation after sundown.
Wind
Wind energy uses simple components which are fast to install, and very reliable. At a height of around 150 feet, the blades are turned by winds, which powers the turbine at the top of the tower. In Denmark, 20% of the country's power is generated by wind. In Sweetwater, Texas, wind turbines have replaced agriculture in areas that were previously struggling to survive drought conditions. The property owners receive income from the electricity generated on their land, and the relatively new industry has revived the community with job opportunities.
The problems with wind energy production include intermittent wind patterns, initial costs, and aesthetics. Many people would rather not look out their windows at enormous turbines or extensive power lines.
Nuclear
Nuclear energy may be the cleanest form of renewable energy currently available. In spite of the inherent dangers of nuclear plants, made even more prominent after the Fukushima disaster in 2011, the benefits to the environment are great. Nuclear energy produces extremely low-emission power to many more households than other energy sources, with a much smaller overall footprint. Much of the waste is recyclable. For example, a power plant in France is able to recycle 96% of spent fuel cells, and the uranium and plutonium is re-processed into new fuel.
The main deterrent for nuclear energy production is the up-front costs of establishing a plant. While the revenue stream relies on energy generation, that energy cannot be generated without the initial investment.
Energy Summary
The comparisons of the pros and cons of different energy sources was very interesting to learn about, though I was disappointed that Dr. Tinker did not explore wave energy options, a personal favorite of mine. On a global scale, I had never before considered the cost of supplying power to the millions who are currently without. The increase in demand could exceed both the current man-made infrastructure capabilities and the environmental capability to recover. Dr. Tinker's proposal of simply using less energy really resonated with me. I consciously try to limit my own power consumption, but I realize that I could do more.
Overall, it seems that many other countries have embraced the implementation of renewable power sources, and tend to brag about them. In comparison, it seems that the U.S. is locked into an oil dependency that few are willing to acknowledge or reduce. In the near future, while I refuse to own anything even resembling a Prius, I do believe that I can drastically reduce the amount of vehicle it takes to transport myself from point to point. I hope that others will begin to feel the same, and reduce the amount of energy used piece by piece.
*All pictures borrowed from google images.
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