Things I Learned This Semester #22 - 27: Energy Edition Part II

Now, where did we leave off last time?  Oh, right, alternative energy sources. I touched briefly on the potential that solar technologies have to offer.  But there are a number of other alternatives to the currently fossil fuel driven system we use.

#22 - Another alternative that is currently in use is in several places across the world is nuclear power.  Maryland actually gets around 30% of it's electricity from two nuclear reactors at the Calvert Cliffs Nuclear Power Plant, and this is actually a much cleaner source of energy than the coal that powers the bulk of the state.  There is a negative stigma associated with nuclear power that, prior to the beginning of this semester, I have to admit I kind of bought into.  But today my opinion has changed.  The fact of the matter is, despite the few well known accidents that have occurred at nuclear power plants, it is a very safe and controlled process.  And according to the International Panel on Climate Control (IPCC), there are enough world uranium reserves (the fuel nuclear reactors need) to provide energy for the next 85 years.  The spent fuel could even be reprocessed and used again in breeder reactors. This would give us over 1,000 years of energy at current usage rates.  There is the issue of the radioactive waste produced in the process of creating this energy, and any means of storing it would have be safe, secure, and long-lasting.  But looking at the big picture, nuclear is not as bad as it seems, especially when you consider the currently used alternatives, and the volume of waste they are producing.

#23 - Geothermal heat energy is another sustainable option.  Very sustainable, in fact, because any portion we are able to extract would seem like nothing compared to the 10³¹ J internal heat content of the Earth. The United States actually did a fairly good job of tapping into this energy resource in 2010, producing more electricity from geothermal than any other country.  Globally, 2.420856 x 10¹⁷ J of electricity were produced by taking the heat from the Earth to heat a liquid (usually water) in order to turn a turbine or generator to produce electricity. Geothermal electricity plants still produce and released dissolved gasses, like carbon dioxide, into the atmosphere (around 400 kg od CO₂ per 3.6 x 10⁹ J of electricity), but this is a very small number compared to what is produced by conventional fossil fuel plants.

#24 - As I mentioned in the previous post, around 1-2% of the energy coming from the sun is converted directly to wind energy.  That's between 50 and 100 times more than is converted into biomass by all of the plants on Earth.  So it stands to reason that harnessing the wind would be a reasonable option.  Windmills have been used for quite some time to power a variety of machinery, and today they can be used to generate electricity. At the end of 2009, 2% of global electricity consumption came from wind turbines.  And it is a technology that could be implemented on a large scale almost immediately.  But like direct solar generated electricity, the trouble with wind is that it is not always available. And so we return to the storage issue I mentioned in part one.

#25 - Thankfully, there are a number of storage options on the table right now.  Some utility companies that generate electricity from solar and wind technologies use pumped-storage hydroelectricity generation.  In these systems, excess energy is used to pump water into elevated reservoirs, where it cam later fall back down through turbines to generate additional electricity when it cannot be generated by the wind or sun.  Thermal energy storage systems are used in a similar fashion.  Water or molten mineral oils are heated with excess energy, and then that heat energy can be used to generate steam to turn turbines to generate electricity during dark or wind-less times.  The Solar Two power plant used molten salts in this fashion from 1995 to 1999 with an energy storage efficiency of around 99%. Advanced batteries would be the ideal for both large scale and individual use if you are looking to get "off the grid" completely, but they are expensive because of the cost of the materials it takes to build them.  Hopefully, in the near future, this will no longer be the case.

#26 - In 2006, transportation accounted for 28% of energy used in the United States.  And the price of gasoline at the pump keeps increasing on a daily basis, at least in my neck of the woods. And of course, there are a number of pollutants associated with the burning of gasoline in a combustion engine.  Is the solution to this problem the electric car?  Whether it is a plug-in hybrid (PHEV) or battery electric vehicle (BEV) you are thinking about buying, the cost is still relatively high, and the payback time is great.  But you use less fossil fuels, and that's good, right?  That depends on where you get the electricity you're using to charge your vehicle.  If you buy a BEV for use around town, and charge it at home in Maryland, that car may not be powered by gasoline, but it will more than likely be powered by electricity from coal.  Foiled again!  Of course, the carbon emissions coming from the burning of that coal at the power plant would be less than if your cars engine were burning gasoline directly.  And if you happen to charge at home and get your electricity from renewable energy sources, that's even better.  But the cost of the electric car is still high, and that means that sales of this type of vehicle will not be widespread until the costs are comparable to that of a gasoline powered vehicle.

#27 - The Green Revolution of the 1940s was started with the intention to eliminate world hunger by advancing agricultural technology.  The use of pesticides, fertilizers, machinery, irrigation systems, and new plant cultivars increased agricultural production by 1000% from 1960 to 1990, and hunger decreased during the same period of time.  But as agricultural output increased, the energy required to do so also increased, meaning that today we see a decrease in the ratio of crop production to energy input.  And the sad news is, most of the energy that goes into this industrial agricultural system comes from fossil fuels.  That means that their is a direct correlation to the cost of energy and the cost of food you buy.  Whether it is in the form of transportation, chemical fertilizer/herbicide/pesticide production, or machinery, our system of food production has become petroleum based.  The food energy we put in our bodies comes from fossil fuels.  And yes, I know that in the previous post I mentioned that fossil fuels are technically a form of solar energy.  But it stands to reason that when it comes to the production of crops, we could cut out the non-renewable middle man, and rely directly on solar energy to power our bodies.  It's worked for Life on Earth so far, so it doesn't seem like a ridiculous notion.

And that, in short, is what I learned in my physics course this semester.  The law of conservation of energy says that energy cannot be created nor destroyed.  But it can be conserved, in more ways than one.  Yes, it can be conserved in that it it can change it's location in a isolated system over time while remaining constant.  But it can also be conserved in the sense that energy use can be reduced and made more efficient.  Energy efficiency results in near immediate savings, and simply reducing our energy use adds no additional cost.  I think the most important thing I took away from this course was that on a large scale, policy and politics plays a big role in how we generate and use our energy.  And global progress can sometimes be impeded by individual nations looking to protect their own interests. But each of us can still do things on the level of the individual to conserve our energy "commons".  Keeping our tires inflated, using public transportation, or simply driving less saves energy that goes into transportation.  Obtaining foods from local, sustainable sources while in season is better for energy use, and your health. And turning off lights and other electrical appliances when not in use saves energy and money on your utility bills.  Reduce waste, reuse what you can, and recycle whatever your city will allow.

Yes, we need global change, and that will take political power and a whole lot of money to make it happen.  But I believe any person that thinks their individual actions can't make a difference is sorely mistaken.  Dino-nerds, geek out with me for a moment as you recall James Gurney's Dinotopia from your childhood (or perhaps more recently), and the second line of the code: "One raindrop raises the sea."  There are lots of other good bits in there too, but throughout my years, that particular phrase has really stuck with me.  I hope it sticks with you too.  And if you want to learn more about any of the topics I briefly covered, let me know in the comments or by e-mail.  I'm always eager to hear what you guys think.





Reference


Lathrop, Daniel P. 2012. Personal communication in PHYS105, University of Maryland, College Park.