A Theoretical Study of Two Novel Concept Systems for Maximum Thermal-Chemical Conversion of Biomass to Hydrogen

J N Chung

doi:10.3389/fenrg.2013.00012

Abstract

Two concept systems that are based on the thermochemical process of high-temperature steam gasification of lignocellulosic biomass and municipal solid waste are introduced. The primary objectives of the concept systems are 1) to develop the best scientific, engineering, and technology solutions for converting lignocellulosic biomass, as well as agricultural, forest and municipal waste to clean energy (pure hydrogen fuel), and 2) to minimize water consumption and detrimental impacts of energy production on the environment (air pollution and global warming). The production of superheated steam is by hydrogen combustion using recycled hydrogen produced in the first concept system while in the second concept system concentrated solar energy is used for the steam production. A membrane reactor that performs the hydrogen separation and water gas shift reaction is involved in both systems for producing more pure hydrogen and CO2 sequestration. Based on obtaining the maximum hydrogen production rate the hydrogen recycled ratio is around 20% for the hydrogen combustion steam heating system. Combined with pure hydrogen production, both high temperature steam gasification systems potentially possess more than 80% in first law overall system thermodynamic efficiencies.

Highlights

In recent years, the global warming and climate change issues have created controversies and public concerns that involve the energy industry, government leaders, and society at large (Holdren, 2001; Kalicki and Goldwyn, 2005)
(2) The hydrogen combustor in System I that provides the supercritical steam gasifying agent is a very clean combustion process and draws the fuel from the H2 produced by the gasification process (~20% of total H2 produced), so the system is self-sufficient and there is no need for external heat supply
(3) The solar heating in System II that provides the heat for producing supercritical steam at 1000°C is a very clean process with a renewable source and zero carbon release

Summary

Introduction

The global warming and climate change issues have created controversies and public concerns that involve the energy industry, government leaders, and society at large (Holdren, 2001; Kalicki and Goldwyn, 2005). Renewable and sustainable carbon-neutral energy resources with high energy contents should be considered and explored for the future needs in the power, transportation and manufacturing sectors of the economy (Wilk, 2002). The concept systems introduced in this paper would contribute to an enabling technology to convert lignocellulosic and municipal solid waste (MSW) biomass resources to useful energy, from thermodynamic efficiency and system technology development standpoints, as well as from emission impacts on the environment, water and weather. The main objectives for proposing these systems are (1) to introduce the best scientific, engineering, and technology concepts for converting lignocellulosic and MSW biomass together with agricultural and forest residues to clean energy (liquid fuels, chemical feedstock, electricity, and mechanical power), and (2) to minimize the water consumption and detrimental impacts on the environment (air pollution and global warming)

Objectives

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Discussion

Conclusion