John C. Kramlich
M E 430
Advanced and renewable energy conversion systems and technologies are treated. Included are high efficiency combined cycles; renewable energy conversion involving solar, wind, and biomass; direct energy conversion and fuel cells; and nuclear energy. Environmental consequences of energy conversion and environmental control are discussed. Prerequisite: M E 323.
Energy conversion systems transform raw energy resources (e.g., fuel, wind, sunlight, falling water, and nuclear reactions) into useful work, such as mechanical or electrical power. One of the most important things the Second Law of Thermodynamics tells us is that there is an upper limit to the amount of work that can be extracted from any of these raw resource streams. This is called the maximum work potential or availability, and it is relatively easy to calculate. Energy system design engineers strive to grab as much of this possible work, although capital cost and environmental constraints always influence the final design. By the end of this course, the student should be able to (1) find the maximum possible work that can be extracted from an energy resource stream, (2) calculate where in a complex energy conversion system the greatest inefficiencies lie, (3) be able to evaluate the various ways in which one can attack these inefficiencies. In other words, the student will become able to design modern energy conversion systems.
The featured technologies include:
1. Advanced gas turbine systems. These represent most of the large stationary power generation equipment under construction today. The technologies include gas turbine fired cogeneration, combined cycle systems, and hybrid water and/or steam injected gas turbine systems. Their popularity stems from their very high efficiencies, and their low capital cost. They are the benchmark against which other emerging energy systems must compete.
2. A brief overview of nuclear reactor technology. Although there is no construction activity in this area now, it still represents a significant portion of our electrical generation capacity. It is our one existing option for eliminating CO2 emissions from large-scale power generation should we become serious about the greenhouse gas issue.
3. Fuel cells. These emerging systems directly convert the chemical energy in the fuel to electricity. This bypasses the usual step of burning the fuel to get a high-temperature gas, and then generating work via a heat engine. They have the potential for very high efficiency electrical generation, although much of this potential has yet to be realized. The key issues here are almost all associated with engineering, e.g., how to optimize cell stack performance without driving manufacturing costs too high, and how to reduce manufacturing costs to make the technology competitive with existing power systems. The low temperature systems demand hydrogen fuel, which must made by chemically reforming other fuels, a process which loses much of the work potential contained in the original fuel. Our approach here will be to engineer the integrated fuel cell system, starting with the raw fuel, and proceeding through the reformer, the fuel cell, and the utilization of the waste heat. This is designed to provide the student with an overall appreciation of integrated fuel cell technology, with a focus on the challenges that must be overcome to reach commercialization.
4. Solar power. Free energy from the sun can be captured directly via photovoltaics to make electricity, or can be captured as thermal energy for heating or for thermal cycles. Photovoltaics are, however, very expensive and very inefficient. We will explore the reasons for both of the commercialization barriers.
5. Wind power. Issues here involve location selection and designing for maximum efficiency.
For each of these technologies we will also look at:
1. The external climate (economic, environmental, and regulatory). What factors will be driving change in the industry during your career.
2. The advantages and problems associated with both existing and emerging technologies, (i.e., which of the technologies are best suited to meet the external challenges described above and thrive).
3. The engineering analysis procedures used by practicing engineers to characterize the performance of advanced energy systems.
4. The technical background associated with each of the technologies.
Student learning goals
General method of instruction
The class consists of four weekly one-hour lectures. There is no text for the class, although you will need access to a standard undergraduate thermodynamics text for reference and property tables (any of the common thermodynamics books will be fine, e.g., Cengal and Boles, Moran and Shapiro, Wark and Richards, Black and Hartley). Instead of a text, we rely on the lecture notes (posted on the web), handouts, and web-based resource materials. The class includes two midterm exams and one comprehensive final.
The usual perquisite for this course is ME 323, the second quarter ME undergraduate thermodynamics course. Alternate prerequisites can be substituted if they involve classical thermodynamics and an introduction to classical heat engine analysis. Preparation in radiative and convective heat transfer is helpful, although not necessary, for the solar portion of the course.
Class assignments and grading
Problem sets are assigned once or twice a week, with some of the assignments resembling open-ended design projects.
The grading usually consists of homework: 30%, midterms: 20% each, final: 30%.