18 June 2013

Coal is dirty.


As studies show, electrical energy is directly correlated with economic prosperity and increased human lifespan.  As a result, it is no wonder that the trend across history has been toward increasing energy use and, more recently, electrification.  In the case of less-developed countries, with little access to "clean energy" systems like solar, wind, and nuclear, this electrification is frequently accomplished by burning coal.  Today, let's take a look at some of the health effects caused by the combustion of coal.

First of all, how much coal do we use worldwide?  The World Coal Association (2009) states that worldwide, about 41% of electricity comes from coal.  This number varies, from as high as 93% in South Africa to as little as 41% in Germany (home of the world's largest repository of solar panels).  On a worldwide, annual basis, that comes to a whopping 7678 megatons of coal.  In terms of volume, that's 307 BILLION cubic feet (about 8,300 Empire State Buildings) of coal per year.  Each ton of coal puts off 2.86 tons of CO2 -- a total of 22,000 megatons of carbon dioxide per year, assuming complete combustion.  It's no wonder that coal combustion is the largest contributor to greenhouse gas emissions.

World energy use by source

Carbon dioxide isn't the only thing coal releases, though.  It also releases sulfur dioxide (a major cause of acid rain), nitrogen oxide (also acid rain, plus smog), small particulates (which aggravate the lungs and other systems), heavy metals (arsenic, cadmium, mercury, lead, and more), and particles of uranium.  In fact, due to the particles of uranium contained in coal, and released when it's burned, coal combustion releases 100 times as much radioactive material into the environment than an equivalent nuclear reactor.  Wow!  Of course, the actual amount of radiation involved (about 2 mRems / year) is trivial and hardly a health hazard...

The mining industry causes significantly more deaths than industry as a whole.

The real health hazard comes from those tiny particulates, sulfur dioxide, and heavy metals.  These materials mean that residents of areas near coal plants have elevated levels of health problems like chronic obstructive pulmonary disease (COPD), hypertension, lung disease, and kidney disease.  Odds are even worse for the miners -- 49.5 out of every 100,000 coal miners died in 2006.  That's an eleven-fold increase over private industry as a whole.

Want to see a really striking set of numbers?  Check out these mortality rates for different energy sources.  Worldwide, coal accounts for 160,000 deaths for each trillion kWh (10^12 kWh).  Given that we used about 143,000 TWh (1.43*10^14 kWh) worldwide in 2008, that's almost 10 million deaths worldwide due to coal combustion alone.  Compare that with nuclear power, which at 90 deaths per trillion TWh at 13% of worldwide capacity causes about 1700 deaths annually.  Even the renewables (listed in the graph above as 3% "other renewables"), assuming the low mortality rate of 150 / trillion kWh of wind, gives only 643 deaths at a remarkably tiny production rate.  Huge difference.

Energy Source Mortality Rate (deaths/trillionkWhr)
Coal (elect,heat,cook–world avg) 100,000
Coal electricity – world avg 60,000
Coal (elect,heat,cook – China) 170,000
Coal electricity- China 90,000
Coal – U.S. 15,000
Oil 36,000
Natural Gas 4,000
Biofuel/Biomass 24,000
Solar (rooftop) 440
Wind 150
Hydro – global average 1,400
Nuclear – global average 90

Clearly, with all these health problems (not to mention CO2 emissions) we need a shift away from coal for power production.  There are many alternatives.  The United States is currently championing natural gas as the "clean" alternative -- and considering its relatively low death rate plus its lower emissions, it is definitely a step in the right direction as a transitional fuel.

But not even natural gas will provide us with the total non-reliance on carbon for energy systems, or with a truly indefinite supply of energy.  There are a handful of technologies that CAN.  Solar and wind are good, but they are currently limited by energy storage.  The most promising candidate for base load energy with zero emissions is nuclear power.  But given that you're reading a LFTR (Liquid Fluoride Thorium Reactor) blog, you knew that.  Right?

11 June 2013

Can water be pressurized to form hydrogen?

Recent research from Malcom Guthrie, of the Carnegie Institute for Science, in conjunction with Oak Ridge National Laboratory's Spallation Neutron Source has provided new insight into the ways by which water can be split into its component elements, hydrogen and oxygen.

The work uses a stream of high-energy neutrons to observe what happens to hydrogen atoms (i.e. individual protons) when ice is pressurized to extreme levels -- 500,000 times atmospheric pressure.  Because ice crystallizes through hydrogen bonds, these extreme pressures were once predicted to provide an alternative mechanism for water dissociation by direct, high-strength hydrogen-hydrogen bonding.  These predictions appear to have proven true.

Could this:  

https://www.boundless.com/microbiology/chemistry/inorganic-compounds-1/water--4/
be pressurized to become this?
http://www.fuelcells.org/base.cgim?template=hydrogen_basics



What does this imply for the future of hydrogen production?  My first thought is that these extreme pressures -- half a MILLION times atmospheric pressure -- may make this work impractical for use in real-life situations.  But what if similar effects were observed at more manageable levels -- say, 100 or 1000 times atmospheric pressure.  Could these effects provide a more economical, less energy-intensive mechanism for producing and storing hydrogen molecules, instead of low-efficiency electrolysis?


Source from Carnegie: https://carnegiescience.edu/news/unfrozen_mystery_h2o_reveals_new_secret