Bioenergy with Carbon Capture and Storage

Using Natural Resources for Sustainable Development

José Carlos Magalhães Pires, Ana Luisa da Cunha Goncalves, Jose Carlos Magalhaes Pires

• Publisher: Academic Press
• Year: 2019
• Print ISBN: 9780128162293
• eBook ISBN: 9780128166000
• Topic: Technologie et ingénierie
• Subtopic: Énergie

Bioenergy with Carbon Capture and Storage: Using Natural Resources for Sustainable Development presents the technologies associated with bioenergy and CCS and its applicability as an emissions reduction tool. The book explores existing climate policies and current carbon capture and storage technologies. Sections offer an overview of several routes to use biomass and produce bioenergy through processes with low or even negative CO2 emissions. Associated technology and the results of recent research studies to improve the sustainability of the processes are described, pointing out future trends and needs. This book can be used by bioenergy engineering researchers in industry and academia and by professionals and researchers in carbon capture and storage.- Presents the most recent technologies in use and future trends in research and policy- Examines the bioenergy production and biomass processing value chains, including biorefining, negative emission technologies and the use of microalgae- Includes techno-economic analysis and sustainability assessment of the technologies discussed, as well as an overview of the latest research results

Chapter 1

Negative emission technologies

Francisca M. Santos, Ana L. Gonçalves and José C.M. Pires, LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal

Abstract

Carbon dioxide (CO₂) is an important greenhouse gas (GHG), which concentration in the atmosphere has been rising since the Industrial Revolution due to emissions from anthropogenic activities (mainly burning of fossil fuels). The continuous CO₂ emissions may lead to a potentially irreversible climate change (global warming) and ocean acidification. Even if CO₂ emissions could be cut to zero today, the environmental impacts would persist in the future due to the long residence time of this GHG. Therefore an international agreement was signed, aiming to limit the increase of the global temperature at 2°C. In this context, CO₂ capture from large point sources is gaining the attention of the scientific community as a mitigation option. The pure stream obtained can be transported and stored, avoiding the emission of high amounts of CO₂. However, since half of the CO₂ emissions come from diffuse sources, capturing CO₂ from the atmosphere may be also needed to fulfill the mitigation targets. Despite the higher costs when compared to CO₂ capture from large sources, negative emission technologies (NETs) present several advantages: (1) it can capture CO₂ emitted from different sources at different locations and time, and (2) the sequestration site can be placed anywhere, avoiding infrastructures’ transportation. NETs can be divided into two routes: (1) direct air capture—using physicochemical processes and (2) indirect air capture—using biological processes. This chapter aims to present an overview of the main NETs, demonstrating their advantages and drawbacks. Currently, there is no single process that can be considered the only solution to achieve the mitigation goals. Research efforts should be made to completely assess the environmental impacts and reduce its costs, possibly through a process integration.

Keywords

Atmospheric CO₂; biochar; bioenergy with carbon capture and storage; negative emission technologies; sustainability

1.1 Introduction

Carbon dioxide (CO₂), an important greenhouse gas (GHG), has been added to the atmosphere by anthropogenic activities, mainly by the burning of fossil fuels. As a consequence, severe changes in the world’s climate are happening, and different ecosystems are being threatened [1]. Since the pre–Industrial era, the population and economic growth have largely increased the global average atmospheric CO₂ concentration. Between 1750 and 2018 the CO₂ levels have risen from 280 parts per million (ppm) to, approximately, 408 ppm [2,3]. Global CO₂ emissions are about 36 Gt CO₂/year [4], where 91% are originated from the combustion of fossil fuels [5]. As a consequence, the ocean has absorbed about 20%–40% of the CO₂ emitted to the atmosphere since the Industrial Revolution [6]. This increase has a greater impact on the chemistry of the ocean surface, especially on the levels of hydrogen ion concentrations (H⁺). The continuous rise in the atmospheric CO₂ increases the levels of H⁺ in the ocean, which leads to its acidification. Surface ocean pH is already 0.1 U lower. At this rate the decrease of ocean pH is expected to be 0.4 U by the end of the century and 0.8 U by 2300 [7,8]. Simultaneously, the carbonate equilibrium is affected, resulting in dramatic impacts on marine life. Reducing ocean pH decreases the amount of carbonate ions available, and it may become more difficult for some species, such as coral reefs and calcareous plankton, to form biogenic calcium carbonate [9]. Thus these species are more vulnerable to dissolution, and their habitats are severely threatened. It is estimated that already 30% was damaged, and approximately 60% may be lost by 2030 [10]. In addition, as a GHG, CO₂ can absorb and emit infrared radiation, which affects the global temperature. The planet’s average temperature has risen about 0.9°C since 1880 [11], mainly driven by the increase of CO₂ emissions, causing the melt of glaciers and other ice and, consequently, increasing sea levels [12].

In order to reduce the atmospheric CO₂ concentration, several nations recognize the urgent need to commit to a low-carbon economy [13,14]. In 2015 countries adopted an international agreement to combat climate change under the United Nations Framework Convention on Climate Change (21st Conference of the Parties—COP21). The Paris Agreement aims to avoid the increase in global average temperatures in 2 °C and to make efforts to limit this increase to 1.5 °C above preindustrial levels. In order to limit warming the total amount of CO₂ emitted needs to be finite, and it includes the utilization of both preventive and remediation strategies [15]. Preventive measures are related with (1) improving energy efficiency, (2) increasing the use of low-carbon fuels, (3) promoting the use of renewable energy sources, and (4) using geoengineering approaches [for example, afforestation and reforestation (AR), which increase the natural carbon sink]. Remediation methods are linked to carbon capture and storage (CCS) techniques [16,17]. The anthropogenic sources of CO₂ can be divided into two categories: large stationary sources (such as power plants and industrial activities) and dispersed sources (mainly from transportation). While CCS can reduce CO₂ emissions from large sources (around 85%–90%), the aim of reducing anthropogenic CO₂ emissions close to zero requires CO₂ capture from diffuse emissions as well (e.g., cars, trucks, airplanes) [18,19]. Since the capture from diffuse sources may be technically impossible, due to its large number, CO₂ can be captured from the atmosphere using negative emission technologies (NETs), which offset these emissions. Capturing CO₂ from the atmosphere may be more expensive than capturing from stationary points, but this supplementary approach presents some advantages: (1) CO₂ capture is sector independent, in other words, it can capture CO₂ emissions from both diffuse and point sources; (2) transportation infrastructures may be avoided since the CO₂ capture unit can be placed anywhere; (3) the separation process is less affected by the presence of other pollutants (e.g., nitrogen oxides, sulfur oxides) since their atmospheric concentration is much lower when compared to flue gases [17,18,20]. Nevertheless, the NETs’ feasibility to meet the required scenarios is still questioned. Technical and social barriers, such as the absence of political actions, public understanding and acceptability of these technologies, or the side effects that NETs could have, are conditioning the scale-up of the technology [21,22]. NETs encompass several techniques, and it can be divided into two routes: (1) direct air capture through physicochemical processes [absorption, adsorption, ocean alkalinity enhancement (OAE), and soil mineralization] and (2) indirect air capture through biological processes [afforestation, ocean fertilization, algal culture, bioenergy with CCS (BECCS), and biochar]. This chapter aims to present an overview of the main NETs, also presenting the advantages and drawbacks of each technology.

1.2 Direct air capture

The concept of capturing CO₂ from air is not new. It was previously applied as a life-support system in submarines and spacecraft, but it was mentioned for the first time for climate change mitigation purposes in 1999 by Lackner et al. [23]. Since half of the CO₂ emissions come from diffuse sources, its capture from the atmosphere is essential to comply with the targets of limiting the warming within 1.5 °C–2 °C. However, this technology presents challenges regarding the high energy demands associated to the low CO₂ concentration on ambient air (approximately 350 times lower than a typical coal-based flue gas [17]). Large air volumes need to pass through the absorbers to collect significant amounts of CO₂. Therefore capture technologies that use heat, cool, or pressurized air cannot be applied in air capture due to their economical unfeasibility [23,24]. The atmospheric CO₂ can be captured from the following methodologies: (1) absorption, (2) adsorption, (3) OAE, and (4) soil mineralization.

1.2.1 Absorption

Absorption is a process where the gas (ambient air) captured enters in contact with a physical or chemical solvent in an absorption column. The solvent has specific characteristics that only absorb CO₂ and let the other gases pass [25]. The CO₂-rich solution is usually transferred to a regeneration column, where the CO₂ is removed, and the solvent is recycled to be further reused. Physical absorption is based on Henry’s law, and the dissolution of CO₂ on solvents is attributed to electrostatic ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Foreword
• Preface
• Acknowledgments
• Introduction
• Chapter 1. Negative emission technologies
• Chapter 2. Carbon capture technologies
• Chapter 3. Pre- and post-Paris views on bioenergy with carbon capture and storage
• Chapter 4. Rightsizing expectations for bioenergy with carbon capture and storage toward ambitious climate goals
• Chapter 5. Status of bioenergy with carbon capture and storage—potential and challenges
• Chapter 6. Role of the ocean in climate stabilization
• Chapter 7. The climate mitigation potential of managed versus unmanaged spruce and beech forests in Central Europe
• Chapter 8. Carbon dioxide capture and use by microalgae in photobioreactors
• Chapter 9. Beyond fractionation in the utilization of microalgal components
• Chapter 10. Environmental impacts of bioenergy crop production and benefits of multifunctional bioenergy systems
• Chapter 11. Killing two birds with one stone: a negative emissions strategy for a soft landing of the US coal sector
• Chapter 12. Bioenergy with carbon capture and storage: how carbon storage and biomass resources potentials can impact the development of the BECCS
• Chapter 13. Economics and policy of bioenergy with carbon capture and storage
• Chapter 14. Bioenergy with carbon capture and storage in a future world
• Index