Described types of integration in Chapter 9 are related to the integration of mate­rial flows either for their transformation or for the separation of their components. Similarly, the energy integration of the different steps for ethanol production is possible. Energy integration, particularly heat integration, looks for the best utili­zation of energy flows (heat, mechanical, and electrical) generated or consumed inside the process with the aim of reducing the consumption of external sources of energy such as electricity, fossil fuels (oil, natural gas) mainly used for steam generation, and cooling water. Pinch technology is one of the most widely applied approaches for heat integration in the process industry, especially in the petro­chemical industry. This technology provides the necessary tools for design of the heat exchanger networks including plant utilities. During preliminary design of the heat exchange network, pinch technology allows one to obtain the best values of many process parameters as the type of utilities and their specifications.

Pinch technology has been utilized for the design of heat exchanger networks (HEN) during ethanol production. For the case of ethyl alcohol production from molasses, a process flowsheet was simulated and optimized by heat integration emphasizing the separation step by distillation (Sobocan and Glavic, 2000). The simulation was made by shortcut and rigorous methods in order to perform the heat integration. For ethanol concentrations up to 95.7% by weight, the optimal configuration corresponded to one single column and not two, as had been pro­posed. This work demonstrates the usefulness of heat integration since the optimal design showed a 27% reduction in the total costs (Cardona and Sanchez, 2007).