Energy around the world has conventionally been created by the combustion of fossil fuel, non-renewable resources such as coal and oil. This does not, however, make for a sustainable future because burning these types of fuels causes pollution, contributes to climate change, and has inherent problems in its extraction. There are alternatives to these fuel sources as well, but evaluating both the current fuel sources we use now and the ones that we may deign to choose in the future before we invest in them is important.
When we rate an energy source we look at several of its characteristics. One important characteristic of a valuable energy source is the net energy, or the usable amount of high-quality energy available from a given amount of an energy resource. Similar to the net profit of a business, this part of an energy resource is important because it helps investors determine whether or not they will support a particular energy source. An energy source with a negative net yield, such as hydrogen fuel cells, would need government intervention in order for it to survive the energy market, which makes many hesitant to invest in those types of energy.
Energy waste is a component of energy sources that can be improved to also increase the net energy ratio of a fuel. One big waste is using a gas-guzzling vehicle instead of one that has better gas mileage. If energy waste was reduced then carbon dioxide emissions would decrease, people would save money, and reliance on imported oil would decrease.
Oil is one energy source that is nonrenewable. A black, gooey liquid, made of hundreds of different combustible hydrocarbons as well as small amounts of sulfur, oxygen and nitrogen impurities make up crude oil, or petroleum. One problem with oil is supply because the nonrenewable resource can run out. After being pumped out of porous rock, the pressure in the well decreases when peak oil production has been reached. Once we pass global peak production the price of oil rises as well as
other types of the fuel such as tar sand and oil shale. These fuels are becoming easier to extract but their downsides are numerous because they have low net energies. As mentioned before, they cannot compete in the open market without subsidies because of their low net energy. The extraction process is also extremely dirty as it involves stripping the entire land or pumping it like crude oil.
Another fuel is natural gas, a mixture of gases of which 50-90% is methane. It also contains smaller amounts of heavier gaseous hydrocarbons such as propane, butane and hydrogen sulfide. It has a very high net energy yield and can be burned to produce electricity or heat. The two types of natural gas are conventional natural gas that lie above reservoirs of crude oil which is pressurized into liquefied petroleum gas stored in pressurized tanks. The liquefied natural gas is converted from natural gas at high pressures and low temperatures where it can be transported overseas so the United States import much of it from countries like Japan. It is used mostly in rural areas not served by natural gas pipelines.
Burning natural gas is cleaner than burning crude oil or coal but it still releases carbon dioxide and other air pollutants into the atmosphere and even so it as seen as an important fuel for making the transition from oil to coal to solar and wind power. but it is of a lower net energy yield than it is in other forms. Unconventional natural gas may also be an option as underground shale and ice captures natural gas and methane however it costs too much to get natural gas from methane hydrates and releasing methane also speeds up climate change.
Coal is a solid fossil fuel that was formed in several stages from the remains of land plants that were buried 300-400 million years ago and then exposed to intense heat and pressure over millions of years. Coal generates 42% of the world’s electricity and 46% of the electricity in the United States.
The dirtiest of fuels, coal has been used for centuries to produce energy because it does have a high net energy output but it severely pollutes the air. Sulfur dioxide is released into the air because it creates acid precipitation. In addition, coal-burning plants are the greatest contributors to greenhouse gasses-they count for 25% of greenhouse gas emissions in the world.
Burning coal also emits radioactive waste, in fact coal releases about 100 times more radioactivity than a nuclear power plant, as well as toxic mercury. China, particularly, is the greatest CO2 and sulfur dioxide emitter in the world, which contributes to serious health problems in its populace that it will likely need to deal with in the future. Although coal is cheap, it clearly comes with some baggage.
Coal has been experimented with and the idea has been tossed around that coal can be converted into synthetic natural gas, which would remove sulfur and other impurities from coal. However producing the synfuels requires 50% more coal which adds more carbon dioxide to the atmosphere. Unfortunately synfuels also have a lower net energy fuel and cost more to produce per unit of energy than conventional coal.
Nuclear power is also a source of energy that we learned how to use fairly recently, primarily for generating electricity. 85% of the reactors that are in use right now are fission reactors that are light-water reactors that use water as a cooling agent. Unfortunately around 92% of energy is lost due to dealing with the radioactive wastes produced by a plant. The fuel for a reactor is made from uranium ore mined from the earth’s crust and enriched to increase the concentration of fissionable uranium-235 to 5% which is then processed into small pellets of uranium dioxide. What is interesting is that the energy equivalent of one small eraser-sized pellet of uranium is one ton of coal. When the fuel is put in, control rods moving in and out of the reactor core heat up water in the power plant, and the water then flows out of the plant to remove heat and keep the core cool so radioactivity doesn’t escape into the environment.
Now nuclear power is the slowest growing form of commercial energy and even though the United States has provided huge subsidies, tax breaks, and loan guarantees to the nuclear power industry as the net energy yield is extremely low, this still doesn’t help. One case study to examine is the meltdown at Chernobyl
nuclear power plant in the Ukraine in 1986. This was the most serious meltdown in history, as two simultaneous explosions blew the roof off of a nuclear power plant, releasing a radioactive cloud that would spread over the entire planet. Poor reactor design led to this incident, however it also led to a stigma about nuclear power, even though it has one of the lowest accident rates in the energy industry.
The most difficult goal is trying to find a way to store the long-term radioactive wastes safely at a central site. About 3 or 4 years is all that it takes for high-grade uranium fuel in a nuclear reactor become spent, useless, and must be replaced. The rods must be stored for tens of thousands of years in order for them to become more stable but the controversy arises when the places are chosen for this storage. Yucca mountain is a possible viable storage option but many think that the storage there is not safe enough for the thousands of years that it needs to be kept stable. Also unfortunately there are not enough plants open now to expand the industry to lessen our
dependence on foreign oil.
Nuclear fusion, or the fusion of two isotopes at extremely high temperatures to form a heavier nucleus, may be an option to produce energy as it has less of the risks involved than fission does. There is no risk of a meltdown or releasing radioactive materials into the environment and terrorism that is usually a worry for fission plants is not worrisome because bomb-grade material is not required for it.
The alternatives to these nonrenewable sources of energy are wide-ranging but not all of them are viable for implementation in the world community. Alternative energy is a big step in the right direction to improve energy usage but methods of distributing and using energy must also be taken into account. New energy sources are important, but methods of increasing energy efficiency are more effective and extremely easy to implement.
We waste an unnecessary amount of electricity because of simple inefficiency. If we were to use it we could lower utility and gasoline bills, and lower our dependence on non-renewable energy sources like oil. Improving energy efficiency, or the measure of how much work we can get from each unit of energy we use will eliminate the need to produce that energy. A surprising statistic about efficiency is that 84% of all commercial energy in the United States is wasted with 43% wasted unnecessarily due to inefficiency in objects such as incandescent light bulbs, furnaces and other energy-consuming devices. In addition, the design of many buildings is not conducive to retaining heat so excessive heat is often required to heat buildings in the winter, while cooling costs soar in the summer.
The Rocky Mountain Institute is a good example of how to make buildings more efficient. It utilizes design principles that fit the land that they are building in. Much of the energy that would be wasted heating a home is not even needed because of the design that the building allows for it. Installing energy-efficient windows, insulating, and using more energy-efficient appliances are important factors in making homes more efficient.
Some other means of saving energy are as follows. Cogeneration, a system in which two forms of energy are produced from the same fuel source, can also be used in saving energy. The energy efficiency of this kind of system is 75-90% compared to other systems emitting one-third as much CO2 as conventional boilers. Recycling materials in the building process also saves energy and money because you save 75% of energy by using recycled steel rather than producing your own steel and the emission of CO2 is cut down by 40%. Switching from low-efficiency to high-efficiency light bulbs will result in using one-fourth of the electricity that you would if you continued using them. LEDs use one-seventh of the electricity that an incandescent bulb and last 100 times longer.
Transportation can be made more efficient by giving people incentives to switch to more fuel-efficient vehicles as well as attempting to create a network of rails instead of highways. Plug-in hybrid vehicles would likely be the next step in attempting to making vehicular use less wasteful, but unless the grid generates electricity by means other than oil or coal, the carbon released in the atmosphere will remain the same.
But even if energy continues to be generated by non-renewable fossil fuels, all of these energy savings will be for naught, so alternative energy is vital in this venture. When tax breaks, government subsidies and funding for research into alternative energy are increased than they might have a chance to succeed. Also if oil and coal based energy was priced properly, then the external environmental effects that they cause would be factored into their prices and people would be encouraged to switch to alternative energy sources.
Solar energy is one of the most consistent forms of energy available to us on Earth. When we think of solar energy we think of solar panels that take the sun’s rays and
converts them to usable energy, however there is also passive solar technology available. This system absorbs and stores heat from the sun to heat a home all day and night. An active solar heating system in contrast captures energy from the sun by pumping a heat absorbing fluid through special collectors that are mounted on the roof or special racks. An indirect way of using solar energy is by having a living roof on top of a building which is made up of plants that help keep the hot air outside.
Another system is a solar thermal system which uses different methods to collect and concentrate solar energy in order to boil water and produce steam for generating electricity. Unfortunately these systems have a low net energy yield, but it can be raised to make it economically feasible.
Photovoltaic cells convert solar energy directly into electrical energy and, due to their adaptivity, they can be installed on roofs, as tiles, and pretty much any surface. Stationary panels are great, but also rotating panels are great in the sense that they can collect about 30-40% more energy than stationary panels can. Panels can provide energy to off-grid communities that would not be able to obtain energy in any other way because they are able to work in any remote area. Excess energy can even be used to decompose water and produce hydrogen gas, another renewable energy source that will be discussed later. The net energy yield for photovoltaic cells is moderate as well as emitting little to no direct emissions of CO2 and other pollutants but its disadvantages are that it has a high initial cost and sun access is needed consistently.
Another renewable resource is hydro power which uses the falling motion of water to
produce electricity, as water flows through dams, past tidal buoys, or river turbines. Hydropower is the leading renewable resource for producing electricity, but many experts estimate that many existing dams will need to be put out of commission due to the buildup of silt and other particles which inevitably happens at these sites. This power has a moderate to high net energy yield and it is extremely low-cost electricity. A disadvantage previously mentioned, is that dams displace people and disrupt downstream ecosystems.
Tidal power has been utilized as well, as underwater turbines that are much less
invasive constantly turn with the tide. Verdant Power actually installed several in the East River in NYC between 2006 and 2008. If the project is successful then as many as 300 turbines will be used in the river. This is great news for those who are looking to bring sustainability to New York. Wave power has been attempted off of the coasts of England and Ireland, but the costs are high and the equipment is vulnerable to corrosion.
Wind power is another renewable energy source that produces energy when wind turbines on land and at sea convert the wind to electricity. It is the second-fastest growing source of energy after solar cells. Denmark is one country that gets 20% of its electricity from wind but is aiming for 50% which is good for job creation and the environment. Many complain about the sounds that wind turbines make when they are located close to peoples’ homes so there has been a move to place wind turbines off-shore as opposed to in the vacant areas on land.
Wind farms can be constructed rather quickly (around 9 to 12 months) so the only
real thing stopping this source of energy from expanding further is the storage of energy. Like solar cells wind turbines cannot operate all day long but need the capability to have backup power. Suggestions have been made to connect wind farms to an updated electrical grid so this problem doesn’t need to be addressed. It is an energy source with a moderate to high net energy yield which motivates many to look at it as a probable prospect in the future.
Biomass and liquid biofuels have been considered by many to be a viable alternative, as they are made of plant and animal wastes that can be burned directly as a solid fuel or converted to gaseous or liquid form. What is beneficial about this is that this is a carbon neutral practice, so whatever carbon was in the atmosphere is put back in the atmosphere if the emissions are monitored extremely closely, there are complications as well.
There are other environmental disadvantages to using bio fuels though. Having biomass plantations helps fix the problem of running out of viable sources to burn but the repeated cycles of growing and harvesting these plantations can deplete the soil of key nutrients. Biodiesel and ethanol is being used in place of petroleum-based diesel fuel and gasoline. Their advantages include that gasoline and diesel fuels are concentrated in a particular area while the crops that create biofuel can be grown anywhere. However these plantations would decrease biodiversity in more areas than before as well as degrade soil, push small farmers off of land and raise food prices. Algae has been considered as a biofuel option, but the breadth of its coverage would not reach the entirety of the market.
Geothermal energy is another alternative energy source that comes from heat that is stored in soil, underground rocks, and fluids in the earth’s mantle. One system that is used is a geothermal heat pump system that exploits the temperature difference between the earth’s surface and underground at the depth of 3-6 meters.
Hydrothermal reservoirs are also of service as they provide steam that can provide heat or power homes and buildings. The United States is the largest producer of geothermal energy but its not even close to the amount of electricity that Iceland gets from geothermal energy-all of it.
Finally, hydrogen can be used as a fuel. The advantages of hydrogen include lowering the amount of outdoor pollutant problems as well as greatly reducing the threat of climate change. On the flip side unless hydrogen fuel, which is produced by heating water or passing electricity through it, is produced by
means of alternative energy then the fuel will still contribute to climate change. But unfortunately the net energy yield of hydrogen fuel is negative so more energy is put in to obtain the fuel than what comes from it and it will also require a lot of subsidies in order to compete in the open marketplace. A more viable option may be using larger, stationary fuel cells to provide heat and electricity.
Choosing a more sustainable future means that we have to keep the future in mind as well as the return on investments. For this reason, the best energy basket of decentralized energy grids would involve a mix of wind power, tidal power and solar power. To aid in the transition to this power, nuclear may come in handy for grid technology. In general the end of fuel vehicles is at hand and plug-in vehicles should come to stay. If they are allowed to be attached to these new power sources then there will be a reduction in this sector, while also trains can help this problem of inefficiency in transportation. In all, a plethora of the solutions mentioned will bring the United States to a cleaner future.