Monday, June 22, 2009

Learning More About Energy Choices

If you have taken the time to read the paper that I wrote for EM443 in the fall of 1991, you will see that I had some pretty significant conceptual errors in my understanding of both turbo machinery and the politics and history of energy industry developments. I was definitely naive and had a lot to learn. Fortunately, I was in a great place to learn and had access to a world class university library.

I also began what remains a habit today - I started participating in on-line discussions using the handle of Atomic Rod. (Aside - just this past week I met someone for the first time who told me that she used to read my posts on USENET about atomic energy and that is part of the reason that she got interested in the field. That was a humbling experience and one that makes me realize that words do have meaning and impact.)

In the Naval Academy library there were several sections that focused on energy topics that included numerous shelves of books talking about nuclear energy from a variety of points of view. At one time, the Naval Academy had one of the largest nuclear focused engineering programs in the country under the title of Marine Engineering; by the time I was doing my research that program had nearly completely disappeared. It had been ten years since Rickover had retired, the 80/20 split (80 percent of the students in engineering and science majors, 20 percent in "bull" majors like History, English and Political Science) had gone the way of the dodo bird, and political science was the most popular major at the school.

For my purposes that turned out to be okay; there were plenty of good technical references from the days when the Marine Engineers demanded resources and there was a depth of coverage of the political debates that dominated the 1970s and 1980s.

Dr. Chih Wu - USNA's Alternative Energy Guru

I decided I needed some more depth to my understanding of energy topics in general, so I signed up for Dr. Chih (Bob) Wu's course in Alternative Energy. Dr. Wu was kind of a local celebrity; he had published a number of books including one on ocean thermal energy conversion. He was also quite a dynamic teacher.

One day, Dr. Wu and I had a conversation about his research interests. I knew he had started off in nuclear related fields and wondered why he had shifted to alternative energy systems. He explained that he never lost interest in nuclear, but that essentially all of the research money for nuclear power had disappeared by the mid 1970s and he had to do something to support his academic advancement. I knew that several of the professors did work for Naval Reactors, but Dr. Wu told me that was not an option for him because he wanted to publish his work.

After I had taken Dr. Wu's formal courses in Alternative Energy, I asked him to mentor me for an individual study research project. I am pretty sure that was an almost unique request - having a serving company officer as a research student at USNA - but Dr. Wu agreed. I learned a lot about conducting research and writing technical papers during that semester and owe a good deal to Bob's cheerful and questioning attitude, especially since I was working in an area that was somewhat outside of his usual academic interest areas.

As it turned out, Dr. Wu got interested in what I was doing and even worked with me on a published paper on the topic - my first ever published academic paper. (If you do not want to order the official published version, I have posted the advance copy with one of the reviewer's comments. I am still looking for the original article in the periodical - I have moved several times since 1993.)

(Update: June 27, 2009: Here is a link to a scanned PDF of the paper titled Nuclear Powered Gas Turbines: An Old Idea Whose Time Has Come that was published in the Proceedings of the IASTED International Conference August 5-7, 1992.)

Not Invented or Developed Here

During the same time that I was working with Dr. Wu, I made contact with several of the people who had published articles on high temperature reactors and gas turbine nuclear plants. Colin MacDonald from General Atomics was one of the most prolific authors on the topic with dozens, if not hundreds of papers published in various engineering journals. Richards T. Miller (CAPT, USN ret.) was another guy with whom I corresponded and whose papers I read with great interest.

Both of those gentlemen opened up a whole world of information to me about pretty well developed projects designed to take advantage of the steady heat that nuclear fission can produce by combining it with the steady, low cost flow that can be provided by modern gas compressors and used by modern turbines. In both cases, they warned me that my employer - the US Navy - did not have any interest in pursuing nuclear plants that were not steam plants. Both of them had received rather stern warnings from Naval Reactors about articles that they had published in various technical journals advocating the use of such machinery on board ships or submarines. I have included a copy of one of the notes that I received from Colin; I found it attached to a rather dusty paper.

During my recent digs through history files, I also found a letter to the editor from Richards Miller to the Naval Institute Proceedings written after I had left the Navy - the first time - and published my own article about using closed cycle nuclear gas turbines as the basis for future submarine propulsion plants. That, however, is getting a little ahead of the story.

My correspondence with those gentlemen and others like them helped me to answer one of the questions I had after writing my first paper - why was there such little information or development if the idea was such a good one? This is something that young, idealistic people often ask themselves when they find a great idea buried in a library or on a back shelf. Looking back through the lens of a bit more experience in the world, I have a bit more understanding of the real depth and logic behind a "not invented here" attitude.

Once an organization picks a path forward, they make a tremendous investment in that path, especially when it is something as complicated as not just one nuclear power plant but an entire fleet of them. Tooling, machinery, training programs, and supply chains are not easy to change. Attempting to change them can often result in what systems engineers call "hunting" which is a rather unstable condition that provides a lot of movement with little forward progress. Unlike a lot of people that have run afoul of NR's desire to keep control of their destiny, I get it and admire their continued success at refining the PWR steam plants that they invented rather than hunting for something better. That does not change my frustration with their efforts to slow down or halt others from thinking about new or different ways to capture and make use of fission heat.

So after learning that part of the challenge that had slowed closed cycle gas turbines was technical inertia, I continued digging to see if there were any technical challenges that had limited development. One of the other things that I have learned in researching successful and unsuccessful technology programs is that the unsuccessful ones often have a hard barrier to development that gets minimized in promotional materials prepared by boosters. The successful ones also have their challenges, but they have somehow managed an acceptable work around that could be implemented in time to allow commercial introduction and acceptance.

Areas for Technical Improvement

As I learned more about the closed cycle gas turbine proposals - and nearly all of the papers that I read were about proposed systems rather than real ones - I became convinced that the promoters just did not understand how difficult it was going to be to build and operate the machines that they drew on paper. Nearly all of them included multiple stages of heat exchangers for intercooling and recuperating, all of them proposed very high gas pressures, and nearly all of them proposed a control system that involved large pressurized storage tanks of gas that could alter the system pressure to alter its mass flow rate.

Based on what I had learned from my friends about combustion turbines, I realized that these proposed plants did not have the simplicity advantages shown by commercially successful gas turbines. Without some changes, it looked to me like closed cycle nuclear heated gas turbines were destined to remain on paper. I'll have to leave it here for now - time to go earn a living.

Sunday, June 21, 2009

The Adams Engine™ Story From the Beginning

The Adams Engine™ started off with a Boolean search on the following string - "nuclear AND gas turbine". Amazingly enough, there were dozens of hits with articles about various projects and conceptual designs that combined the benefits of nuclear reactors producing the heat and Brayton Cycle gas turbines turning that heat into useful power. I did that search in the fall of 1991, while auditing a course in power conversion (EM443) taught by Professor Mark Harper at the US Naval Academy. I was on shore duty after just completing a 40 month tour as the Engineer Officer of the USS Von Steuben, SSBN 632 (GOLD).

It is funny how little things can change your life. There I was, a thirty-one year old lieutenant commander with ten years of commissioned service, a wife, and two young daughters. Within a few months of performing that search, I had written a paper on nuclear gas turbine engines, had become addicted to spending as much free time as possible devouring everything I could find on the topic and I was trying to figure out how to turn the paper designs I was doodling into something real. Though I have no intention of dwelling on it during this tale, I have to admit here and now that there were several people in my life, including my lovely and loyal wife, who were not at all pleased with my new obsession.

This blog will not shy from the personal, but it is mainly aimed at trying to share the thoughts and technical decisions that have resulted in the concept I call the Adams Engine™. (By the way, that name itself has a story which I plan to share along the way.)

What's Wrong With Steam?

If you have ever done much reading about nuclear power plants or even received an introduction at a visitor's center or in a textbook, you will probably be familiar with the idea that nuclear reactors are a means of producing heat that is used to boil water to create steam that then turns a turbine and produces electricity. Some of the many people that fight against developing nuclear energy generators like to demean this process by saying something like "just another way to boil water". Of course, boiling water is a venerable and useful thing to do with large scale heat sources; technical historians have often pointed to the development of the steam engine as the main driver in the Industrial Revolution that enabled rapid travel and reliable, mass production of many wealth enabling commodities.

However, as a steam plant engineer officer, I had a pretty deep experience base that led me to understand that steam power has its disadvantages that had resulted in the development of several more advanced cycles used to convert heat into useful mechanical power. Steam was fine for locomotives, factories and ships, but steam automobiles were far too bulky and balky for mass consumption and the Wright Brothers would have never gotten off of the ground if they had to carry a boiler and feed water with them. As time moved on, the machines like diesels and jet engines used to power smaller, lighter applications had grown up to compete quite well with steam for the larger scale applications like ship propulsion and were even making large inroads in the electric power generation market.

There is always an advantage in using less material when making a product and in making products that take less effort to operate. Steam plants by their nature require lengthy, thick-walled piping systems, heavy water storage tanks, and very careful chemistry control to reduce corrosion. In their boilers, multi stage heat exchangers and condensers, they also use a multitude of thin walled, small diameter tubes that are in challenging chemical, thermal and physical environments that tend to lead to deterioration over time.

Because of the large temperature variations and high pressures used, there is always a need for great care to prevent material failures that can cause serious injury or death. Steam plant operators are a proud bunch that need excellent training and often extra pay to account for the difficulty and importance of their assigned work. Even with the extra pay, it is often difficult to attract enough people to the field; the nature of steam plants also leads to a rather uncomfortable work environment characterized by high ambient temperatures and elevated humidity.

These characteristics of steam plants can be mitigated with advanced designs and materials along with automated control systems, but they can never be eliminated. I am proud to be a steam engineer, but I recognize that steam is not for everyone, especially if they happen to be accountants. The only places where steam can still be competitive in power markets is where it enables the use of really low cost fuel - like lignite or coal - that has too much "stuff" in it to burn cleanly enough in an internal combustion engine or in Brayton cycle turbine engines. The need for reasonably clean fuels in those systems is not just because of concerns about pollution - the ash and other contaminants in coal, lignite and many biomass fuels would degrade the internal components of pistons and turbines so much that the machinery would fail.

Traditionally, steam has also been applied in nuclear fission power plants, even though the fuel releases its heat very cleanly. A major reason that nuclear power plants are considered more expensive than other alternatives like combustion gas turbines is actually associated with that assumed need for steam as the working fluid.

In the Navy, we had been taught that diesels and gas turbines had replaced steam in most applications because of the reduced complexity of operation, the reduced manning required, and the smaller machinery systems required. Our teachers acknowledge that the choice had required the use of higher quality, more expensive fuel, but the tradeoff was considered to be worth it except in cases like very large, high speed ships that consume enough heat to make fuel costs a large consideration or on submarines where oxygen and exhausts are strictly limited.

Is There An Alternative to Steam For Fission Heat?

Before I had served as Engineer Officer, I had attended the Navy Postgraduate School in Monterey, CA. While there, I had a running mate named Mike LeFever who had just finished serving as an engineer officer on a gas turbine ship; we often talked about the difference in his experiences and mine while running along the path between Monterey and Pacific Grove. While struggling with steam generator chemistry, leaky steam valves, and slow plant warm ups during my tour, I often thought back to those conversations. However, I also used to tease Mike about "that underway replenishment thing" and the need for large smokestacks to dump his plant's waste products. I liked having a plant that could run for decades between refuelings and that allowed us to breathe while submerged.

When on shore duty at the Naval Academy, I decided to take a few advanced engineering courses. You see, though the Navy allowed me to serve as an Engineer, my undergraduate degree was in English, so I felt a little disadvantaged at times in groups of my peers and wanted to fill in some gaps in my detailed knowledge. As a member of the staff/faculty, I could take the courses for free. (There are not many people that take advantage of that benefit; I have been stationed at the Academy for 4 academic years and have never seen any other officers in courses with me. I guess I really am kind of a geek - or maybe just a cheapskate who prefers free classes without credit to the same class at another school in the evening.)

The first course I took was Power Conversion and one of the assignments was a paper on an advanced power system. That was the assignment that took me to the library and initiated the search to determine if it was technically possible to combine the mechanical advantages of Brayton Cycle gas turbines with the fuel cleanliness and density of uranium fission reactors. I realized that not only was it possible, but that it had been recognized for years as an almost ideal way to capture and use fission heat.
"The "ultimate" nuclear plant for merchant ship propulsion appears to be some form of direct cycle reactor-turbine, eliminating steam and other forms of intermediate heat exchange. There are indications that such a cycle might be a pressurized gas reactor coupled directly to a gas turbine."
Source: Crouch, Holmes F., Nuclear Ship Propulsion, Cornell Maritime Press, Cambridge MD, 1960 p. 140
Once I figured out that atomic Brayton Cycles were possible, I decided to apply one of the important lessons I had learned as an Engineer in Rickover's part of the Navy. I began "pulling the string" to figure out why this idea had not been pursued to wide scale implementation.