Fusion – A Look at the Future

The picture to the left is of the University of Michigan's Laser Chamber - considered to be one of the most intense lasers in the world. The red beam is NOT the laser it's self, its a sighting laser used to aim the main laser. This is an infrared laser that is being illuminated by a phosphorescent card. It may be hard to see, but the reason the laser seems to be tapering toward the left is because it is being focused at a specific point.

For many decades the promise of fusion power has been dangling like a carrot and vowing endless, safe, clean power. Each year it seems like the day that we will actually realize this dream keeps getting pushed back further and further. But, honestly, I don’t really know anything about how a fusion reactor might operate, what waste, if any, it may produce, or when we might see these plants in operation. However, I do know someone who can answer some of these questions and so I sat down with my friend Chris McGuffey to discuss the future of fusion. Chris is working toward a PhD in Nuclear Engineering at the University of Michigan, in Ann Arbor.  Michigan has one of the best nuclear engineering graduate programs in the US (here), and the laser my friend is working with as part of his research is lauded to be the most intense laser in the world (2008). His research is focused on the physics of lasers and particle beams, or as he puts it; “Specifically I work to create electron beams and x-ray beams which may be substantially cheaper than those produced by conventional accelerators. Additionally the same physical mechanisms are important in the "fast ignition" and "direct drive" schemes of inertial confinement fusion.”

Through my discussion with Chris, I can present you a vision of the future:
Let me transport you 50 years into the future (assuming the world doesn’t end in 2012) to the opening of one of the first commercial fusion reactors. Imagine a thick walled stainless steel chamber that is spherical in shape and ten meters (or think 10 yards for the metric challenged) in diameter. Pointed at the center of this sphere, where the fusion reaction is taking place, are a number of instruments, and lasers. The reaction is fed by a steady stream of fuel pellets that are about as large as the head of a pin and are being fired into the center of the reactor at 5-10 times per second. As each pellet is zipping into the chamber, lasers lock onto the pellet applying light pressure and heat to initiate a burn.  When the pellet reaches the center of the chamber, an extremely powerful and amazingly short burst from the lasers will have heated it enough that the fusion reaction will begin. What is being termed a “burn” is not the traditional burn, like how wood burns; this burn is two isotopes of hydrogen being fused together to form an alpha particle (a helium atom without any electrons) and one neutron, and then perpetuating this reaction throughout the fuel pellet. The heat that is produced when the atoms fuse is not what will be used to produce electricity.  Instead you have one fast neutron that will shoot off into a fluid that is laced with the isotope lithium-7. When the neutron interacts with the lithium, another reaction occurs. In this reaction, the fast neutron combines with the lithium and causes it to split into one tritium, one helium, and a slow neutron as well as creating heat (Nave, 2006). The heat will be used to create steam to turn a turbine that will be used to generate electricity.

Portals to view into the laser chamber.

However, this vision of the future makes a few assumptions; one, we have developed materials or processes that will be able to survive the constant bombardment of high energy neutrons for a reasonable, and economical amount of time; two, we will be able to capture the energy efficiently. Lastly, can we capture more energy than it takes to ignite the reaction. Probably, one question that should be asked and some people may not be asking is: is this worth it? I, for one, have been led to believe that fusion is this holy grail for the power industry, and promises to be clean, safe and to have unlimited power potential since the fuel is the most abundant element in the universe: hydrogen. Call me a cynic, but I want to know what the catch is. Nothing is free, and nothing is so easy, so I have been wondering if fusion is as clean and safe as I have been led to believe.  Well, I thought it was a good question and that is what I hoped to glean from my discussion with Chris.  His answer was a little unexpected; fusion is safe, is clean and has the potential to be everything that is promises.  Since the process is not like a chain reaction in a fission reaction where we have to be constantly reigning it in, there is no possibility of a catastrophic event; like a nuclear explosion or melt down.  Also, since the fuel is hydrogen, and all the necessary containment is relatively light material - lighter than uranium, so any radioactivity produced will be short lived.  When Chris was referring to short lived, he did not mean short on a geological time scale, he meant short on the human scale. So the waste, can be managed in our life times, and in a hundred years or less the waste will be safe.  Also, it will not be as "hot" as the waste produced by current fission reactors that is also very long lived.  Think tens if not hundreds of thousands of years.  As for environmental impact, the fusion reactor will produce as many green house gases as a conventional nuclear power plant.  What I mean by that, is that the reactors largest contribution of green house gases will likely have to do with its construction and not its operation.  The heavy equipment to forge, move, and build the reactor will burn fossil fuels (presumably) that would otherwise not be burned.  So then if this is so great what is the hold up?  Research.  The technology required to commission the first reactor is so daunting, and expensive.  The impression I got from Chris was that 50 years may be a some what optimistic time line.  Specifically, we will need to have some vast improvements in materials to make this dream a reality.

There are two main reactor designs emerging from research and development programs, one is the Inertial Confinement Fusion (ICF) design that I had illustrated above. High power lasers are used to initiate the fusion reaction by applying intense amounts of heat and pressure. When I say pressure, the pressure is indirectly applied by the lasers.  They heat a little vessel that the fuel pellet will be contained in.  As the vessel is heated to incredible temperatures in extremely small fractions of a second (think 1x10^-9 to 1x10^-14 seconds) the vessel will explode inward, and compress the fuel.  The second design uses magnetic force to squeeze the atoms together to initiate the fusion reaction, and is referred to as Magnetic Confinement Fusion (MCF). The International Thermonuclear Experimental Reactor (ITER) project is building a MCF test reactor in Cadarache, France that is expected to run for 30 years. Construction is beginning and is expected to be finished in 2018, followed by 20 years of experimentation.

Above is some of the gear used in the laser lab.

In regards to ICF, there are two major projects in the world. One is the National Ignition Facility (NIF) located at the Lawrence Livermore National Lab in Livermore California. This facility is expected to be the first to achieve “ignition” – meaning that the reaction will produce more power than it consumes. France has also started a project called the Laser Megajoule that will deliver 1.8 million joules of power to the targets and will help to study the physics of the heat and pressures that exist in the center of the sun. 

Currently, the biggest hurdle to building a successful commercial reactor is developing materials that will survive the harsh environment in the reactor chamber. High energy neutrons are shooting out and smashing into the walls of the reactor. As the neutrons strike the walls of the reactor they are damaging the micro structure of the material and will eventually fatigue the steel to such a degree that the reactor vessel will have to be retired. Even though neutrons are very penetrating, and damaging they can be stopped with lead shielding fairly easily.

To the right is a gray wall of duct tape wrapped lead bricks used to shield the lab from powerful X-ray radiation emitted when the particle beam created by the laser passes through the stainless steel walls of the laser chamber.

This is just an introductory article on fusion, I expect to write many more that will delve into more detail as this blog evolves over time.  But just a recap, below are some of the advantages and disadvantages of fusion as far as can be determined at this time.

Disadvantages:
-Not currently a working option
-Very expensive R&D required to have functioning reactor design
-Likely to be very expensive to build the reactors
-Many unknowns

Advantages:
- Cheap, abundant fuel
- No greenhouse gases are produced
- Short-lived, manageable radioactive waste
- No chance of catastrophic explosion or melt-down

I would like to say thank you to Chris McGuffey for taking the time to sit down with me and talk about lasers, fusion and for letting me take the above pictures in the lab.

Energy 101: 02 - The Grid

No doubt, this is one of the most overlooked elements of the entire electric system by both the general public and utility providers alike despite the fact that the power lines are usually the most visible aspect of the power industry.  Most people would consider the grid as being nothing more complex than running wire from a power plant to the various customers and maybe this is partially why it is almost ignored except when the power goes out.  As for the utilities, the transmission lines aren't actually generating revenue like a power plant would.  So it can be easy to see how a utility company would prefer to maintain, and invest in power generation instead of upgrading power lines and other grid elements. 

Above is the substation at the natural gas plant in Morro Bay CA.  Just Past the substation, you can see the the large transmission line towers, and more towers carrying the transmission lines off over the hills.

So what is "the Grid"? 

The power grid is the power lines and associated equipment that forms an interconnected network of suppliers and customers.  This definition does not accurately portray the complexity of the system nor does it express how improving the grid can reduce energy consumption, improve electricity quality and reliability.  One complicating aspect of the electri grid is that electricity cannot be stored in sufficient quantities to meet demand, which means that electricity must be produced at the same rate that is it consumed.    This means that utilities must be accurately predicting demand, and have some excess capacity available for sudden spikes in demand. 

How it works:

Power is generated at a supplier such as a coal plant, a wind turbine, or such. To most efficiently transport that electricity, voltage is increased or “stepped up.”  For instance, the voltage coming out of the steam generator at a coal power plant may be 33,000 volts (abbreviated as 33 KV, where kV = kilo-Volts), and a transformer in an on site sub station will bump up that voltage to 500,000 - 750,000 volts (abbreviated 750 kV). Transmission lines carry this electricity over long distances to various customers.  Some industrial customers may need high voltage, so they will have their own substation that will be tapped directly into the transmission lines and this substation will reduce the voltage to whatever the customer requires. This reduction in voltage is called “stepping down.”

Different cities, communities and residences may have different electrical needs, so how the power gets from the transmission lines to a house may not necessarily follow these steps in every instance, but it’s a good approximation of the process.  High voltage transmission lines will feed a step down substation that will take the 500 – 750 kV and reduce the voltage to 69 kV.  A distribution substation, which is a substation close to a residential neighborhood, will take the 69 KV and step that down to 2,400-19,000 volts that can service a comerical building or small industrial customers.  However, this is still way to high of a voltage for a residential home, so somewhere near the house, usually on a telephone pole, there is one more transformer that is usually described as a garbage can that steps the power down to 110/240V used in the home. 


Different Elements of the Grid: 

Transmission lines:  As mentioned earlier, are high voltage power lines that are transmitting electricity over long distances.  The farther the electricity is traveling the higher the voltage is used to prevent loss, typically 500kV to 750kV.  In 2002, there were 157,810 miles of transmission lines stitched across the US.  Some of you may have noticed that transmission lines have three or six wires.  This is because the electricity is generated in three phases (which is explained in the fundamentals of electricity article), and each wire is carrying a different phase.

Distribution Lines:  These are lower voltage lines that are feeding customers.  These are the ones you would see in the neighborhood around your house and would be the ones that are 2400 volts - 19000 volts.  An example of a distribution power line can be seen to the right.  The metal cylinder on this power pole is a transformer that will step the power down to what the customer requires. 


Substation:  A substation can fill many roles.  Typically its main function is to step voltage up or down and to protect the grid from power failures by isolating sections with the uses of switches.  In 2004, there were 10,287 transmission substations and 2179 distribution stations within the North American power grid.  


Transmission Loss

When electrons flow through a conductor (aka a power line or wire), the metal has some resistance to the flow of these electrons.  Like friction in a mechanical device, this resistance converts energy, in this case electrical energy, into heat.  The more electrons that flow the more that are lost when passed through the conductor.  There are several ways that this loss can be mitigated.  One way is to reduce the amount of current (current = electrons) that is transmitted across the power line by reduce the current and increasing the voltage.  That is why long distance power lines are also very high voltage, since the higher the voltage the less current needs to travel.  Other possible solutions, which aren't as economically feasible, would be to increase the size of the power lines, use new materials that are more conductive, and/or to use more power lines. 





The NPR website has a great map of the North American grid here.



Reference Links:
http://www.npr.org/templates/story/story.php?storyId=110997398

http://sites.energetics.com/gridworks/pdfs/factsheet.pdf
http://arxiv.org/PS_cache/cond-mat/pdf/0401/0401084v1.pdf
http://sites.energetics.com/gridworks/index.html
http://tonto.eia.doe.gov/energyexplained/?featureclicked=2&

Energy 101: 01 - Types of Energy Sources

I plan to organize this blog around the various types of energy sources, so it might be best to define and describe how we produce energy and transmit that power to the consumers.  Firstly the sources are broken into two major categories; nonrenewable and renewable.

The image to the left is the Trenton Power plant in Detroit Michigan.  A 776 Mega Watt (MW) capacity power plant that has three units, the first of which was built in 1949.

Nonrenewable Energy Sources:  These are created by slow geological process and/or have a finite quantity on the earth.  For instance, oil or coal is created in such a slow process, it will take millions of years to create more.  Uranium is a nonrenewable source because there is only a finite amount of this element on the earth, and there is no natural process on the earth that will replenish this source.  In the US coal is the most common fuel source for generating electricity(49.8% according to the DOE), this is mainly because there are extremely large coal deposits in the US and this is a cheap fuel source. 

List of Nonrenewable resources:
Oil
Coal
Natural Gas
Propane
Other Fossil Fuels
Nuclear (Uranium)

To the right are five wind turbines located near the town of Elkton Michigan.  There are a total of 32 wind turbines with a combined capacity of 53 MW.  


Renewable Energy Sources:  Renewable energy is replenished at the same rate or faster than they are used, so they are effectively limitless.  Most all of these sources derive their energy from the sun in some way or another, the only exception to this is geothermal.  For electrical power generation, hydro power is by far the most common.  When considering all types of energy (heat energy for instance) biomass is the most common renewable energy source.

List of Renewable Energy Sources:
Wind
Solar
Biomass
Bio-Fuels
Hydro (water, such as from dams)
Geothermal
Tidal


My future articles will explain how these various sources are utilized to generate electrical energy and how it is distributed via "the grid."