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Energy On-Demand: The Challenges for Sustainable Energy

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In today's world, energy and power governs all. Electrical energy is needed to help save lives, communicate with friends and family, and complain on Facebook and Twitter. Since the invention of the light bulb, much of the world has gotten "drunk" on electricity, and I do not claim to be energy sober. Right now, I need energy to power the computer that I am using to type this article, the lights in my office, and the music in my ears.

Since having access to technology has become a necessity for many people, it is something we pay for on a daily basis. We need energy for our homes, cars, smartphones, and computers, and since it is unlikely that people will leave these luxuries on the side of the road, the demand for energy will always be present in the United States and the world.

In this article, I aim to explain the challenges of electricity and energy that is gripping the technology based world. My goal is to demonstrate that while the country is trying to move to more environmentally favorable sources, our energy demand forces us to stay with the older methods of fossil fuels. It is important for people to not just understand what energy is, but where it comes from and some of the innovations that can help us work towards efficiency and conservation. Therefore, let's start by understanding energy.

Energy comes in many forms (mechanical, chemical, electrical, etc.) and from many different sources. As animals, we power ourselves through our own chemical energy plant inside our body's cells. We eat food and our body converts that to energy by breaking the food down. However, our technology is dependent on electricity or electrical energy.

In physics, we define energy as the ability to do work. Energy is stored in many different things like sunlight (solar), materials (coal, natural gas, wood), and chemical systems (the human body). Einstein helped us realize that all matter is energy and that is also stored in atoms (uranium - nuclear). The challenge is how do we gain access to these energy sources and have them do work for us. By work, I mean heat our homes, run our cars, and provide power to our smartphones, computers, and other electronics.

Power is defined as the amount of energy used over time. This is a critical distinction, because power and energy are different. However, many people try to equate them. To help you understand the distinction, think of driving, where the distance you travel is energy and your speed is power. Sure, your car has a maximum speed (150 mph or 240 kph), but you rarely (if ever) travel that fast for safety, mechanical, or legal reasons. Therefore, looking at the maximum speed (power) doesn't tell you anything about the amount of distance it can travel (energy). Because of the difference between power and energy, it is important that we look, not at the amount of power, but the overall amount of energy produced. To make it easier, we can look at the amount of energy produced in one year.

In physics, power is given in units of Watts (W) or Joules (energy) per second. This is typically given as a kilowatt (kW), which is 1000 W. From this, we can define energy as the amount of power (kW) for some amount of time (hour - hr). Therefore, energy can have a unit of a kWhr. Just check your electric bill and it will tell you how many kWhr you used last month.

It wasn't too long ago that the majority of the world produced energy by simply burning wood or candles. However, in today's world, we have much larger energy demands. The average US household uses ~1000 kWhr of electricity per month (12,000 kWhr in one year). This is critical because power companies love to tell you how many households are receiving their energy. However, the numbers do not lie. The total electrical energy consumption for the US is about 4.0 PWhr/year or 4,000,000,000,000 kWhr/year (PWhr = petawatt hour), which is about 20% of the world's overall energy consumption. Therefore, there some questions. How do we provide enough energy for people? How do we do this while minimizing the effects to the environment or our overall safety?

Unfortunately, there are no simple answers to these questions. Below, I will go through the main energy sources and discuss their overall energy outputs and how they compare. While environmental issues are important, I will simply mention the main aspects of concern. For further information, look at my previous articles on climate change or electric cars. The main point in this article is to look at total amount of energy that is produced by different sources and how our energy demands are driving the need for efficiency through conservation and innovation.

When it comes to energy, most countries have a breadwinner - the energy source that defines that country. In most countries, it is fossil fuels (coal and natural gas). For over a century, Coal has fueled progress in the United States and will probably continue for a while. Therefore, it is a good place to start.

Coal is essentially compressed carbon and the United States has a lot of it. When burned coal produces ash, CO2, and energy! Some coal technologies are designed to try to stop the ash and CO2 from getting into the atmosphere. However, it just scrubs it out and stores it, which becomes an issue all of its own (Look up TVA Ash Spill) considering the possible toxic and radioactive nature of the ash. When coal burns, the heat it generates will boil water, which moves a turbine to create electricity. Therefore, as with most of the world's power plants, a coal power plant is nothing more than a glorified steam engine. This is similar for natural gas as well, except no ash.

Once the electricity is created, the typical coal burning plant can produce an average peak power output of about 500 MW (megawatt). However, as mentioned before, you need to pay attention to the amount of energy, not the power. If a coal plant runs at maximum power for 1 year, then it will produce about 4.3 TWhr (terawatt hour) of energy per year. Since they do not run at maximum, it is more like 2-3 TWhr per year. For the United States, the total energy production from coal was about 1.6 PWhr and another 1.2 PWhr from natural gas. That is about 70% of the United States electrical energy consumption, but we need about 4.0 PWhr. Even though coal and natural gas is very abundant and not running out for decades (maybe a century), they need help to generate the power we demand.

The next powerhouse is nuclear power. Nuclear power essentially produces water vapor, electricity, and radioactive waste. It basically uses the breaking of an uranium atom (E = mc2) to produce heat to boil water and then we are back to the steam engine, again. The maximum power output can range from 4 GW to 0.5 GW, depending on the number of reactors. This translates to an average about 5 TWhr/year for a nuclear power plant. Currently, the United States produced about 0.8 PWhr/year from nuclear power plants (just under that of natural gas). The main advantage is that you only need a tiny amount of uranium compared to tons of coal and you don't produce CO2 and ash, which is great for the environment. However, nuclear power isn't without its controversies (look up Three Mile Island, Chernobyl, and Fukushima).

Fossil fuels and nuclear power are great at producing energy, and together provide 3.6 PWhr (Out of the 4.0 PWhr used) of electricity for the United States. However, there are concerns about the availability of these resources, because they are not renewable. Once we run out of coal, natural gas, and nuclear materials they are gone. It should be mentioned that nuclear has a longer life span lifespan than coal, because we can reprocess or use other fuels, like thorium or plutonium. However, the fact does remain, that those to will eventually be expended, albeit not for a few centuries. Therefore, the general goal of the world should be to work towards more sustainable energy that is renewable.

This leads us to the alternative energy sources (mainly solar and hydroelectric). Hydroelectric uses the flow of water to produce electricity (essentially taking advantage of gravity). Solar uses the abundant source of energy from the sun, and does this through two different techniques (photovoltaic and concentrated). Concentrated solar uses sunlight to boil water and then back to the steam engine. However, photovoltaic solar uses the properties from specially designed materials to absorb sunlight and produce electricity through complex interactions within the material. Both sources don't produce CO2, which make them fairly environmentally friendly.

In terms of power and energy, hydroelectric can be comparable to coal and nuclear. The Hoover Dam produces about 4 TWhr of energy per year. Altogether, the United States gets 0.3 PWhr of its energy consumption from hydroelectric power. Why so little? Well, the problem with hydroelectric power is you need to build a dam and create a reservoir, which means that you have to displace land and the environment. This leads to many political and environmental questions about the use of the water being put to work. For example, if you dam up the Colorado River and slow or stop it from flowing into the Gulf of California, then you are interfering with California, Arizona, and Mexico's water supply, as well as any states that feed from that source. The trade off is that states typically get some of the energy produced through energy agreements. There is an environmental advantage to hydroelectric. It is the ability to control the flow of river water, which provides some security from flooding waters in the areas below the dam.

If you have been keeping up with the math, then you can tell that we have accounted to 3.9 PWhrs of the total 4.0 PWhr of electricity in the United States. The remaining 1% comes from all other alternative energy sources (solar, wind, tidal, etc.), which is a very tiny amount. Here, I will focus only on solar, but wind and tidal have promise as well.

Solar (Sun) energy is renewable and long lasting (the sun won't expand into a red giant for another 4 billion years), somewhat environmentally friendly, and quite powerful. The sunshine provides about 1 kW of power per square meter, which makes it sounds too good to be true. Considering that solar energy is probably the best source of energy, why is it not being used? Well, the catch is that you just have to figure out how to collect it.

We have the ability to harness it in a number of ways, solar panels and concentrated solar power plants, which were mentioned above. With solar panels, scientists are able to use complex materials to convert the Sun's energy into electrical energy. The main problem is that they are not that efficient. You need to spend over $15,000 just to retrofit your home for solar use. If you can afford them, solar panels can pay for themselves, in energy savings, in just under a decade. There are photovoltaic solar plants that can produce larger amounts of energy, but they typically produce only 0.1 TWhr per year and take up a large amount of space.

Unfortunately, solar panels is just not powerful enough to power big cities like New York or Los Angeles, but solar can be very helpful rural areas and towns. Therefore, while it may not, at this time, have the ability to be the "breadwinner" for the country, it is definitely useful in helping lower our dependence on the other sources. If you can trim a little bit off the top, then you can save a lot in the long run.

For big energy from the Sun, you need a solar concentration plant. Concentrated solar power plants use a large area of mirrors to reflect light into a power station where the light is concentrated and is essentially used to boil water like a traditional power plant. Remarkably, concentrated solar power plants can have a large power output. The Ivanpah Solar Power Facility in Ivanpah, California is predicted to have a maximum output of 392 MW, which is comparable to that of coal and small nuclear power plants, and is quite impressive. When you look at the total annual energy output in a year, this facility is predicted to produce about 1.0 TWhr of energy, which about 50-60% less than that of a coal burning plant. This is impressive and will surely displace a considerable amount of pollution each year.

Although, the question can be asked, if the power is comparable, then why is the energy output so low? Well, this is because the solar plant can only run when there is sunlight, which for California is about 3000 sun hours per year, which is quite high. Therefore, the annual energy output is dropped dramatically. This is different for coal, nuclear, and hydroelectric, because they can run 24 hours a day/7 days a week.

The main issue that faces solar plants is the amount of area or space needed. Photovoltic fields are large with very little output, compared to the others. The Ivanpah Solar Power Facility (concentrated solar) takes up about 3500 acres (5.5 sq. mi or 14 sq. km). Therefore, if we wanted to run the United States (4.0 PWhr/year) off only solar collector plants, then you need to use an area of at least 22,000 sq. mi (or 56,000 sq. km), which is slightly less than the total land area of the state of West Virginia. When compared to the area and cost of a standard nuclear or coal plant, this makes the construction of these power plants can be very costly.

Now, that is a lot of information and you may be confused as to what it all means. Well, the interpretation is in the eye of the beholder. Money, area, and overall output make solar a tough sell as the majority contributor to the countries power grid, but that does not mean we need to abandon it. Solar can definitely help make our energy grid more sustainable. Innovations to improve efficiency can make these less used options much more viable. Even small contributions are useful and lower our need for the larger sources.

Since our energy demands are ever increasing, it is unlikely that current alternative energy sources are going to take over as a majority, and that is the problem. That is the energy crisis. There is only so much coal, natural gas, and nuclear material on Earth. Sure, we have enough to last for the next couple of generations, but those will run out. Our need to draw our energy from a more diverse number of energy outlets is critical.

Right now, our energy is on-demand. If you use more energy on a hot summer day, then the coal plants burn more coal, a nuclear power plant will lift the reactor control rods a little higher, or a hydroelectric plant will turn on another turbine to provide you that energy. This is another challenge for solar power plants. Once the sun goes down, the plant will generate less energy and it is harder to respond to the energy demands. However, if we can store energy more efficiently, then we can move away from the on-demand energy grid.

To do this, we need to develop better battery technologies and more efficient ways to store energy. By making batteries lighter with higher capacities, we could revolutionize our power grid. Efficient battery technologies will make the combined efforts of solar, wind, and tidal power much more viable. By working to make more efficient solar technologies, small towns and rural areas can become self-sufficient and large solar collector plants can be feasible to power bigger cities.

Batteries are huge area of research, but they are not the only place where efficiency can be improved. The use of complex materials can lead to harnessing of energy from many sources like radio waves, temperature differences, and changes in pressure. We don't normally think of these things, but scientists are working on them. Imagine your cell phone being charged, not by plugging it in or using a solar panel, but by a material or device the converts the radio waves around us into usable electrical energy. How about increasing your gas mileage by using a thermoelectric material to convert the heat from your engine into electricity or the pressure from your rotating tires into electricity using piezoelectric materials. Many of these are already realities.

Advances in technologies require energy and so does the world with which we live. We need to move on from our steam engine approach to energy and get more innovative in how we use energy. We can't just put the car on cruise control and go the back to make a sandwich.

Sources: The US Energy Information Administration

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