Energy Discussion

Today, we discussed alternative energy and the kinds of infrastructure we will be seeing during our field experience. Each form of energy has its advantages and disadvantages.

Hydroelectric Power

We discussed hydroelectric power and how it works, particularly at Glen Canyon Dam. The water is held at a certain level behind the dam, forming an artificial lake or reservoir. The force of the water being released into the intake transforms potential energy into kinetic energy, and turns the turbines to generate electricity. After passing through the turbine, the water flows back into the river on the other side of the dam.
In order to increase efficiency, pumped storage may be considered. This involves pumping the water that was used to generate power back into the reservoir to be used again. Pumped storage is not done at the Glen Canyon Dam because of the geologic formations present- it would be a major engineering problem. Another option is to use diversions to use water along natural elevation change to create power at a power station, then the water is released back.
There are several problems with hydroelectric power. Creating a dam involves years of construction and requires large amounts of land to be dedicated to the construction site, which ends up displacing people who were previously living along the river. This also contributes to ecosystem destruction and wildlife losses around the construction site, and continues after the dam is built because you are restricting the mobility of wildlife in the stream. Restricting mobility of the water can also lead to nutrient flow retardation, which causes problems downstream. Problems can also occur within the reservoir, including sedimentation as well as herbicide contamination because people don't want plants growing in or around the lake, so they use herbicides. Evaporation losses are also a problem at reservoirs. Dam failures can lead to large scale flooding, which disrupts ecosystems as well as human environments. Dams also contribute to seismic activity due to the added weight on the land mass from concrete and the water in the reservoir. Although hydroelectric power is cleaner than burning fossil fuels, all of these issues have an effect on the environment and should be considered.

Wind Energy

Wind energy is very clean and virtually "free", but the wind isn't very predictable and cannot be stored. The stronger and more consistent wind occurs at night in the winter time, which happens to be when there is not as much power demand. This is a major problem and makes wind energy not as efficient as one might think. Wind energy is also controversial in certain areas because birds have been killed by the blades of the windmill structures.

Solar Power
Solar has great potential in the United States, contrary to what some people may think. Most of the United States has "good" or "very good" potential for solar energy. Using passive solar design to build your house in the right orientation can make a difference in your energy use. Utilizing passive solar heat can also make a difference, which is using an absorption structure with no moving parts to gather and hold heat. Active solar heat pumps heat-absorbing medium through a collector rather than passively collecting heat in a stationary object. You could also use a green roof to help insulate your home and reduce your cooling and heating costs. Utilizing these methods is important because water heating actually consumes 15% of US domestic energy budget.
High temperature solar is a different type of solar energy method. This involves curved and reflective parabolic mirrors that collect light and focus it onto a concentrated point. This heats the oil in the pipes, which in turn heats water and turns it into steam. The steam is used to turn the turbines and generate power. The Kramer Junction is the most famous example of high temperature solar technology. At night they actually use gas to power their plant, so it's not totally green. However, they are producing the most "green" energy during the day when it is in peak demand.
Photovoltaic solar energy is created by photons absorbed by the PV cell material. The energy of the absorbed light is transferred to the semiconductor (silicon) which knocks the electrons loose. The electrons migrate to the front of the cell, which creates a current. The current and the cell's voltage defines the power that the solar cell can produce. the efficiency of energy capture by photovoltaic cells has increased from <1% in 1980 to 10% in field conditions. However, it's still not as efficient as high temperature solar. Also, solar produces DC (direct current) energy, and we transfer it into AC (alternate current) to power our homes. Then, when we plug in something like our laptops, it converts the energy back to DC. This doesn't make sense, and we should start thinking about changing the way we power our homes.

Geothermal Energy
Geothermal energy involves the use of the high pressure and high temperatures that exist below the Earth's surface. At shallow depths, the temperature is a constant 59 degrees, which heats or cools your house. Deeper underground, the temperature gets much hotter, and can be utilized by power stations to create steam to spin turbines. Geothermal energy appears to be "green", however it presents many problems. Sometimes, chemical lubricants are used to ease the flow of water within the pipes. These chemicals can be released back into the groundwater, presenting problems for microorganisms. Using this groundwater can also lead to water loss and cause subsidence problems. Geothermal sites can also cause scarring of the land. Finally, utilizing geothermal energy can cause instability and earthquakes. All of these factors should be considered when planning to utilize geothermal energy.

In general, these alternative energy options may seem "green", but there are a number of flaws that cause environmental problems. Some of these forms of energy, such as wind and photovolatic are not as efficient as one might think. This makes it harder to implement green energy technology everywhere because the supply might not meet the demand, or it's just not worth installing because it's not efficient enough. The method that appears to be the most efficient and cost-effective is simply utilizing passive solar energy. It doesn't cost much to orient your house in the correct way and plant a few trees. We should definitely be taking advantage of this more often.