Mathematical optimization has been used since the early 20th century to improve the profitability of systems and processes. The time-value of money that leads to the concepts of net present value, annual worth, and annual cost of capital investment, is paramount in the optimization of energy systems that typically operate for very long periods. The method of thermoeconomics (which was formulated in the 1960s) and the similar method of exergoeconomics (which emerged in the 1990s) are two cost-analysis methods extensively used for the optimization of energy systems, components, and processes. Calculus optimization and the Lagrange undetermined multipliers are similarly used tools. This chapter begins with an exposition of the basic concepts of economics and optimization theory, and continues with the critical examination of the mathematical tools for the optimization of energy conversion systems using the exergy concept. The uncertainty of the optimum solution, which is an important consideration in all economic analyses, is clarified and an uncertainty analysis for exergy-consuming systems is presented.

Solar irradiance is the source of exergy for all living organisms. Photosynthesis in primeval organisms generates the food for the other species. It also provides the chemical energy in biomass that is used as fuel. Energy conversions in humans produce mechanical work using food as the exergy source. The food intake; the metabolic and thermic processes in the human body; the production of adenosine triphosphate (ATP); and the conversion of the ATP energy into mechanical work are analyzed using the principles of thermodynamics. An interesting conclusion is that humans have evolved as inefficient energy conversion systems, with food-to-work exergetic efficiencies close to 10%. The analyses and a number of examples in this chapter elucidate the application of thermodynamics to biological processes including: production and use of biomass; exergy value of nutrients; exergy spent for vital processes, such as respiration, blood circulation, and maintenance of body temperature; and exergy spent in sports, such as weight-lifting, walking races, the marathon, and bicycling. The chapter also surveys the relationship between exergy destruction, the state of health, aging, and life expectancy.

Our society does not need energy per se. We use the various forms of energy to accomplish desired actions – commuting to work, keeping the interior of homes at comfortable temperatures, producing industrial goods, etc. The so-called “minimum energy” requirement for processes is actually a thermodynamic maximum, defined by exergy. The application of the exergy methodology determines the benchmark for the minimum energy resources that arerequired to perform the desired actions and tasks. The minimum energy benchmark is determined for several processes including: natural gas transportation, refrigeration, liquefaction, drying, water desalination, and petroleum refining. The energy requirements for the lighting, heating and air-conditioning of buildings are also calculated as well as the minimum energy for the transportation of goods and the commuting of persons in conventional and electric vehicles. Given their importance for the transition to renewable energy forms, the exergy method is applied to energy storage systems. Several examples in this chapter offer assistance and resources for the application of the exergy methodology to energy-consuming systems and processes.

Energy usage by an exponentially increasing human population has created environmental problems that are stressing several ecosystems on earth. The concept of eco-exergy (which is not equivalent to mechanical work) has been used to explain the relationship between energy use and the formation of complex organisms in ecosystems. The harmonious co-existence in ecosystems has inspired the notion of industrial ecology as a paradigm for the improvement of exergetic efficiencies and complete utilization of resources. The exergy-environment nexus and the implications of exergy analyses on sustainable development are critically examined in this chapter. Environmental exergonomics, exergoenvironmental analysis that includes eco-indicators, life-cycle exergy analysis, and sustainability indices are theoretical tools that use exergy and other thermodynamic variables to define the state of the environment and to recommend industrial practices that would alleviate the detrimental effects of energy use and would promote global environmental stewardship and sustainability.

Scientists have long studied fire in an effort to both understand the world around them and to prevent the destruction and devastation that uncontrolled fires can cause. Despite many advances in the understanding of fire phenomena, society offers continued challenges that require new approaches for the prevention and mitigation of unwanted fires. In this chapter, fire research is presented through a series of photographs that scale from small, buoyant flames in the laboratory up to large, uncontrolled wildfires and even fire whirls.

There are only so many technologies and devices that have the same type of impact as that of the internal combustion (IC) engine. Its ubiquitous nature pervades our everyday life, many times without us even realizing it. Whether it be the spark-ignited engine driving our vehicle, the compression-ignition engine hauling food to our local grocery store, the jet engine we hear flying 38,000 feet overhead, or the gas turbine powering the laptop screen from which we read this article, internal combustion engines are quite literally intricately and irreplaceably woven into our daily lives. The internal combustion has taken on many different forms throughout its long, greater than 150-year history, but combustion has always been one of its few constants. Indeed, combustion is even in its name and helps differentiate it from other thermodynamic work devices such heat engines and fuel cells.

Combustion is a critically important and extremely visual phenomenon. When properly controlled, combustion is important for a wide range of processes. For example, it is the primary source of power generation for our vast array of electrical equipment and electronics. However, when combustion is not properly controlled, it can be a source of great devastation. For example, uncontrolled wildfires are still a major concern in many parts of the world.

Our perception of a flame is strongly grounded in gravity’s influence. From our every interaction with fire from the first birthday candles we blew out, we each build an intuitive understanding of how a flame interacts with the hot air rising via buoyant convection. As researchers, our perceptions of how flames respond to our controls are unconsciously biased by this intrinsic buoyant flow.