Major 2017 US UCG study, saying that UCG can be a viable source of fossil energy, but that the technology had its heyday in the seventies and eighties and was abandoned then and a lot of senior knowledge and skills has evaporated since. This study supports our attitude that their is no lack of fossil to worry about. The real constraint is the capacity or lack thereof of the environment and atmosphere in particular to absorb all that burned fossil fuel without major consequences for the biosphere. Don’t worry about depletion, worry about how to get away as quickly as possible from fossil fuel.
[e-reports-ext.llnl.gov] – A Review of Underground Coal Gasification Research and Development in the US (2017). David W. Camp – Lawrence Livermore National Laboratory
Here chapter 10 from the report in full, with our highlights:
10 Concluding remarks
Recent U.S. work between 2005 and 2014 improved understanding of UCG’s environmental aspects, produced improved models, matured site selection processes, and contributed to the review and sharing of UCG information. But the main program of the 1970’s and 1980’s is when the big contributions were made.
The United States work of the 1970’s and 1980’s produced great advances in UCG understanding and technical accomplishments. The technical feasibility of UCG was demonstrated convincingly in the western world. It showed that UCG operations could be designed, constructed, started, operated, and shut down safely. The U.S. started with reports from the Soviet Union that described UCG operations and phenomena, making use of Soviet methods during many field tests. Multiple organizations working at different sites developed a breadth and depth of competence and understanding of UCG, and used this expertise to experiment, innovated, and make great advancements in UCG capabilities, and technology.
Air was injected to make low heating value gas (4-7 MJ/Nm3), and mixtures of oxygen and steam were injected to make medium heating value gas (8-13 MJ/Nm3). U.S. field test operations were at the scale of 1,000 to 10,000 tons of coal in a single module, although some of the modules had multiple burn cavities in them.
Operations almost always ended up working, but they did not always go smoothly as planned. Hardware issues and challenges in the underground and extremely hot environment were a frequent reminder that UCG is still low on the technological development curve towards mature industrial practice.
Some field tests resulted in groundwater contamination. This led to a much greater awareness and understanding of this problem, and recommended approaches to minimize it. The final Rocky Mountain 1 test used many of these and contamination was minor, local, and reduced to deminimus levels after a period of pumping. It remains to be seen if subsequent UCG operations, especially ones at scale can be operated with acceptably low environmental impacts.
Technologies were developed, making use of the rapidly improving technology of directional or horizontal drilling and well completions. These showed promise for scale-up to larger and deeper operations while retaining process efficiency and control. ELW had first been tried in a successful improvisation at Hoe Creek III, and then fielded at Rocky Mountain 1. The greatest technological advance was the invention of the CRIP technique. After successful demonstration in the Centralia field test, CRIP was fielded and performed excellently at the Rocky Mountain 1 test. Designs based on CRIP show great promise for cost-effective scale-up to large, deep and efficient operations.
Most of the early large-scale designs and plans naively assumed that large industrial scale operations would be scaled up with a simple pilot program to gather values for a few key parameters. The complexity and difficulty of UCG was such that despite a long well-funded program, the final field test, while deploying many technical and environmental advances, was not much more than twice the size of the first field test, 14 years earlier. There were no long-term operations of multiple modules or the execution of a full “mine plan.” This was not for lack of interest or enthusiasm for industrial scale – scaleup to a size that would help U.S. energy security was always on researchers minds and addressed in nearly every report.
Doing UCG well, smoothly, and with low environmental impact was simply difficult and required experience and improved methods that needed to be invented and practiced. Much of the test design, construction, and operations were being tried for the first or second time by people doing these things for the first or second time. They faced the challenges always posed by geology, thermal processing of coal, and process engineering pilot start-ups, often in remote locations in harsh weather.
This was a period of strong and continued investment, intense activity, and a great pace of development and learning. Some of the keys to its technical success were long-term continuity of funding and the institutions working on it, sharing of results in public conferences and reports, and determination to understand UCG and make improvements.
While the many field tests formed the centerpiece of the program, they were not isolated activities. The program was robust and well rounded. Measurements of gas composition and quality were made to understand and improve the process, not to advertise success. There was iteration between field test observations, scientific understanding of phenomena, modeling, and lab experiments, with each informing and improving the other. Field tests were first and foremost experimental trials and innovation test-beds. They were not marketing endeavors designed to attract investors and project partners. They emphasized learning, understanding, and technical advancement over simple metrics such as tons gasified. Field tests were highly instrumented and monitored, and drill-backs were common. The mechanisms and geometries of cavity growth, and the contents and nature of the cavities became understood. Conceptual models of the process evolved to better explain and predict observed phenomena.
Program participation was well-rounded. Government research institutions led much of the field test and modeling work. Large energy companies and small UCG-niche companies also had programs that typically included field tests, sometimes with government support and sometimes not. University researchers were involved with laboratory experiments and model development. Experience, capabilities, and knowledge and insight were gained by those actively involved. A sizeable cadre of competent researchers, engineers, and technicians by the 1980’s made the potential growth of an industry feasible. This has now been lost, as all but the most junior of participants of that generation are past retirement age.
Their legacy of reports, and reviews such as this one can convey only a fraction of what these workers knew.
The Annual UCG Symposia tied all these efforts together, fostering communication among researchers to build upon each other. Organized by the DOE, participation and written papers were expected of DOE-funded projects, but many others attended and presented. Because of government funding, a large fraction of the activities was documented well in publicly accessible reports.
UCG understanding and technology advanced in the U.S. in a crucible that mixed creative ideas and the hard realities of field test operations. Observations and results, surprises and disappointments, revisions to mental and mathematical models, and the desire to understand and innovate moved the researchers toward better ways of doing UCG.
A consensus developed in the U.S. that UCG’s future would be in deep horizontal seams of moderate to large thickness, ideally with low-permeability coal and surrounding strata, and a strong overburden. Directional drilling and CRIP appeared best for process control, efficiency and economics. Further testing and development would be needed to assure its reliability, sort out a preference for its linear or parallel embodiment, optimize it, and/or innovate to something even better.
The U.S. UCG program of the 1970’s and 1980’s was extraordinarily productive and successful at advancing a difficult technology. It began with very little domestic knowledge or experience. It ended with a large cadre of experts, successful single-module field tests, a good understanding of the phenomena involved, predictive models, new and more efficient technology and methods, and a good understanding and plans of what next steps were needed to scale up and mature to large-scale industrial operations.