Current Trends and Future Developments on (Bio-) Membranes

Cogeneration Systems and Membrane Technology

Angelo Basile, Giuseppe Spazzafumo

• Publisher: Elsevier
• Year: 2020
• ISBN:
  9780128178089
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

Current Trends and Future Developments in (Bio-) Membranes: Cogeneration Systems and Membrane Technology offers an exhaustive overview of the status of cogeneration systems as they relate to advanced membrane technologies for energy savings. The different options for cogeneration are analyzed, both for large (district) and small (residential) size units, with different primary fuels. Energy efficiency is reported and lifecycle analysis is carried out for all different options. The book outlines strategies for engineering development and process intensification of interest to both industrial and developing countries. Finally, the book includes three chapters on lifecycle analysis (LCA) and economic analysis.

• Provides an overview of the interconnections between membrane technology and the systems used for the cogeneration of electricity, such as exhaust gas cleaning, carbon capture and sequestration, and low temperature fuel cells
• Includes two different studies on LCA and a case study on economic analysis
• Presents comprehensive reviews on various traditional cogeneration systems and compares them to alternative membrane-based technologies
• Covers membrane based technologies and their application in co-generation systems
• Addresses key issues on the introduction of process intensification in energy production

Chapter 1

Cogeneration plants for district heating (and cooling)

Stefano Campanari and Nicola Fergnani, Department of Energy, Politecnico di Milano, Milano, Italy

Abstract

This chapter introduces the concept of heat and power cogeneration for district heating and cooling applications. The first section is dedicated to the definition of thermodynamic concepts and performance indexes for cogeneration plants. The discussion then focuses on the main technologies adopted for the prime mover (including gas turbines, steam cycles, combined cycles, internal combustion engines, and fuel cells), from the point of view of plant layout and operating principles; the technology of absorption chillers for cooling applications is also introduced. Finally, the main features of district heating and cooling networks are briefly discussed.

Keywords

DHC; CHP; cogeneration; district heating and cooling; CCHP; primary energy savings

1.1 Introduction

Cogeneration (CHP: combined heat and power) is defined as the conversion of the chemical energy of a fuel, such as natural gas, into thermal and electrical (or mechanical) energy in a unique process (Fig. 1.1). The “prime mover” of a CHP process is a generic system or machine capable of generating electricity and heat; it can be a combustion-based system (e.g., internal combustion engine, gas turbine, steam cycle) or a fuel cell, a generic machine using a fuel or another type of heat source (including renewable sources) as the primary energy input. If a share of the heat or electricity production is used to generate cooling, the entire process is called trigeneration (CCHP: combined cooling, heating, and power).

Figure 1.1 Example of energy flows in a CHP unit. The “prime mover” is any generic machine capable of producing electricity and heat using a fuel as the primary energy source.

The conversion of fuel chemical energy into electricity occurring in power plants generates a high heat rate as waste product, due to the process.therrmodynamic limits. In a typical power plant or centralized electrical production system, heat is dissipated in the environment due to the difficult transportation of thermal power. In contrast, a CHP system located near the user (e.g., an industry requiring heat for its own processes, or a residential site requiring space heating) and connected to a thermal load has the following advantages:

• • fuel conversion efficiency higher than centralized plants due to the recovery of thermal power output from the prime mover
• • possibility to achieve significant economic savings for the final user;
• • reduction of the primary energy demand and the global pollutant emission (e.g., CO₂);
• • reduction of electrical transmission losses and load reduction on transmission lines, thus with a potential increase of the safety of the electric system;
• • possibility (in some cases) of island operation against blackouts, with peak-shaving and power quality management capability; and the
• • possibility to achieve low local emissions when a clean fuel (e.g., natural gas, hydrogen) is used as fuel source.

On the other hand, the main disadvantages are:

• • due to scale effect, distributed CHP may have lower electrical efficiency than in centralized power generation plants, but an exception is the fuel cell technology, which may reach a high electrical efficiency (even higher than centralized plants) without significant influence of the plant size;
• • higher specific investment cost with respect to the large-scale centralized electric power production and local heat production;
• • increase of system complexity, both on the user side and for grid management; and the
• • necessity of specific authorization and permitting procedures, which are generally required for the final user.

Cogeneration efficiency is always reduced if the heat that can be increased in the recovery system is not used. For this reason, many cogeneration systems are sized based on the heat requirement. Any imbalance in the electrical requirement can be adjusted by import or export to the grid, though this is not always cost-effective or possible in a number of markets.

Trigeneration (CCHP) is defined as a cogeneration system in which a share of the thermal energy is used to produce refrigeration (Fig. 1.2). Other cases, where a share of electricity (instead of heat) is used to drive conventional chillers and generate cooling, are sometimes also identified as CCHP, although they belong to a more conventional type, where the cooling demand is simply covered by additional electricity.

Figure 1.2 Energy flows in a CCHP unit.

Making reference to the case of Fig. 1.2, the conversion of the recovered heat is operated through an absorption chiller, fed by the heat recovery from the prime mover. More details on the absorption chiller working principle and performance are illustrated in Section 1.5.

A CCHP system allows achieving the same benefits of a CHP system with some additional advantages including:

• • increase of the plant operating hours as compared to a...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• Preface
• Chapter 1. Cogeneration plants for district heating (and cooling)
• Chapter 2. Application of membranes in district energy systems
• Chapter 3. Impact assessment of exhaust gas emissions from cogeneration PEMFC systems
• Chapter 4. Conventional systems for exhaust gas cleaning and carbon capture and sequestration
• Chapter 5. Membrane technologies for exhaust gas cleaning and carbon capture and sequestration
• Chapter 6. Life cycle assessment of trigeneration plants
• Chapter 7. Residential cogeneration and trigeneration
• Chapter 8. Integrated membrane-assisted reforming in fuel processors for cogeneration applications
• Chapter 9. Residential cogeneration and trigeneration with fuel cells
• Chapter 10. Solar reformers coupled with PEMFCs for residential cogeneration and trigeneration applications
• Chapter 11. Conventional syngas cleaning systems for low-temperature fuel cells
• Chapter 12. Development of membrane reactor technology for H2 production in reforming process for low-temperature fuel cells
• Chapter 13. Case study: Economic assesment of cogeneration of fuel and electricity in an IGCC plant
• Index