Chapter from a book entitled Thermoeconomics, A Thermodynamic Approach to Economics (Third Edition), which deals with the relationships between the disciplines of thermodynamics and economics. Chapter 1 covers historical research on the disciplines, the structural comparisons between of the ideal gas equation and the quantity theory. Chapter 2 concerns a general stock model that can be adapted to represent those of money, labour and economic output. Chapter 3 deals with economic representations of the first and second laws of thermodynamics, work done, internal value and entropic value, reversibility, entropy, particular economic processes and utility. Chapter 4 concerns a thermodynamic representation of production processes, reaction kinetics entropy and maximisation and the cycle. Chapter 5 constructs a thermodynamic money system, using historical data of the UK and USA economies to provide empirical analysis. Particular aspects covered include elastic relationships, entropy, and interest rates. Chapter 6 describes aspect of labour and unemployment. Chapter 7 describes the principles of investment and economic entropy, including DCF, annuities and bonds. Chapter 8 sets out analyses of world energy and climate change to illustrate empirically some of the principles covered by the book.Chapter 9 is a discussion of thermoeconomics and sustainability.