Friday, April 23, 2010

Post # 15: Nuclear Energy As An Enabler of Renewable Energy

I believe the solution to many of our nation's most pressing energy and environmental challenges is more nuclear energy, as much solar and wind energy as we can "tolerate"; a smarter, more robust electrical transmission and distribution system; and electrification of the transportation sector.

I'm all for renewable energy.  Seriously.  Just don't mess-up my view of the mountains, don't kill endangered bats, useful insects, and birds.  And whatever you do – don't dam up my trout stream.

So how much renewable energy (wind/solar) can we integrate into our electrical system?  It turns out we have a few on-going real-world experiments that are giving us some good indicators.  Texas has embraced wind energy in a big way.  Around 9000 megawatts of windpower have been installed in the state.   Sometime back I attended a conference in which a representative from the Electric Reliability Council of Texas (ERCOT) spoke with pride about their success in expanding their wind-turbine-based electrical energy generation.   Then he made the following statement, "We've just about reached the limit of the amount of wind energy generation we can add to the system.  We will have to add more gas turbines or base-load coal or nuclear capacity in order to enable us to increase our wind generation."  The reason?

It turns out that due both to the variability of the wind, and the nature of the electrical generation systems used in today's wind turbines, too much wind energy can actually destabilize an electrical generation system - leading to all sorts of serious problems - including voltage surges, load drops and blackouts.

I guess a good analogy would be to think of two vehicles you might drive.  Imagine one vehicle has a single 200-horsepower engine and a single throttle pedal you control.  Now imagine the second vehicle has one hundred, 2-horsepower engines.  You don't have a throttle pedal for any of them.  Worse yet, each of these one hundred engines runs independently, at varying speeds, on schedules that are very difficult to predict.  Now your job is to drive one of these two vehicles from point A to point B on a fixed schedule.  Which vehicle would you choose?

This (admittedly limited) vehicle analogy illustrates the problem we face as we add more and more wind and solar energy to an electrical grid.  Eventually we lose control and the ability to manage the system.  At some point, the variable nature of the renewable electrical generation overwhelms the predictable and controllable nature of the "base-load" generation and bad things happen.  That point appears to be somewhere in the range of 20 – 30% of the total electrical generation. (Much can also depend on how widely dispersed the wind turbines are in location due to the resultant time variability in generation.)

What do we need to enable us to go beyond 20% renewables?  Well, a breakthrough in energy storage devices for one thing – the ability to stabilize the system by storing the energy being generated that isn't needed on a moment-by-moment basis.  And smarter electrical grids that give us more robust and precise control over both generation and consumption.  Some of our best and brightest are working on these challenges.

So, in the near-term, how do places like Texas add more wind and solar capacity to their generating grid?  By adding more quite, emissions-free base-load nuclear capacity that keeps the percentage of renewables at or below 20% of the total.

So for now, the best "enabler" of renewable energy is .... nuclear energy.

Nuclear and renewable energy - a match made in heaven...

P.S.  For those of you more technically inclined and interested in the subject, a couple of interesting discussions of the Texas wind experience can be found at:


Friday, April 9, 2010

Post # 14: Nuclear Waste May Get A Second Life

Nuclear power is the most dependable and economical non-emitting electricity production source available today – accounting for 70% of the non-carbon-emitting electricity production in the U.S.  However, the once-through nuclear fuel cycle currently employed by our commercial nuclear power plants taps less than 10% of the energy value in the fuel.  Reprocessing and re-use of the contents of used nuclear fuel would enable us to significantly increase the fraction of available energy extracted from the fuel and more efficiently utilize the earth's uranium resources.

The goal of nuclear fuel reprocessing research is to develop reprocessing approaches that are economically viable, environmentally acceptable, and secure from the proliferation vulnerability standpoint.

I had an opportunity recently to spend the day with National Public Radio's award-winning science journalist, Richard Harris.  Richard came our way to research the status of nuclear fuel reprocessing research.  His story ran today on NPR's Morning Edition.  You can read and listen to the story at:

I think Richard did a nice job of presenting the issues, goals, and challenges associated with harnessing that untapped energy in used nuclear fuel and reducing the burden of the spent fuel and nuclear waste legacy of nuclear power.