Substitute Natural Gas from Waste

Technical Assessment and Industrial Applications of Biochemical and Thermochemical Processes

Massimiliano Materazzi, Pier Ugo Foscolo

• Publisher: Academic Press
• Year: 2019
• ISBN:
  9780128156445
• Topic: Physical Sciences
• Subtopic: Energy

Substitute Natural Gas from Waste: Technical Assessment and Industrial Applications of Biochemical and Thermochemical Processes provides an overview of the science and technology of anaerobic digestion and thermal gasification for the treatment of biomass and unrecyclable waste residues. The book provides both the theoretical and practical basis for the clean and high-efficiency utilization of waste and biomass to produce Bio-Substitute Natural Gas (SNG). It examines different routes to produce bio-SNG from waste feedstocks, detailing solutions to unique problems, such as scale up issues and process integration. Final sections review waste sourcing and processing.

This book is an ideal and practical reference for those developing, designing, scaling and managing bio-SNG production and utilization systems. Engineering students will find this to be a comprehensive resource on the application of fundamental concepts of bio-SNG production that are illustrated through innovative, recent case studies.

• Presents detailed scientific and technical information
• Describes up-to-date concepts, processes and plants for efficient anaerobic digestion and gasification of wastes and syngas utilization
• Compares gasification with anaerobic digestion for different situations
• Proposes alternative strategies to increase efficiency and overcome energy balance limitations
• Includes benchmarking data and industrial real-life examples to demonstrate the main process features and implementation pathways of bio-SNG systems from dry and wet waste, both in developed and developing countries

1

The role of waste and renewable gas to decarbonize the energy sector

Massimiliano Materazzi¹ and Pier Ugo Foscolo², ¹Department of Chemical Engineering, University College London, London, United Kingdom, ²Department of Industrial Engineering, University of L’Aquila, L’Aquila, Italy

Abstract

With a continuous population increase and economies expansion, global energy consumption is increasing fast, and so is waste generation, whereas cheap fossil fuels as non-renewable sources are rapidly depleting. A significant transition to renewable sources, along with improved technologies and better waste management solutions, are some of the proposed solutions that can soon reduce the dependency on traditional fossil sources, leading to a slow but consistent decarbonisation of the world energy sector. In this context, natural gas is seen as bridging fuel that will help to meet short-term emission targets for power generation, heating and transport while restructuring the electricity mix towards renewables. Renewable gas or Green Natural Gas (GNG) can, and is being produced via the upgrading of biogas from Anaerobic Digestion of many types of waste feedstock. However, in order to achieve a step change in production capacity, alternative approaches such as via thermochemical routes are also necessary. Depending on the technology improvements, future cost reductions and support schemes, the volume of GNG production will dramatically increase and this increase will facilitate rapid growth of its use to fully decarbonise the heating and transport sectors.

Keywords

Global energy consumption; waste treatment; natural gas; renewable gas; decarbonization pathways; green natural gas (GNG)

Chapter Outline

• Introduction 1
• Decarbonization pathways 3
• The role of waste in decarbonizing the energy sector 5
• Natural gas and renewable gas 7
• Overview of waste treatment technologies for the production of green natural gas 11
  • Biochemical conversion 11
  • Thermochemical conversion 13
  • Other “green gas” technologies 14
• Conclusions 16
• References 17

Introduction

Today’s global community faces a challenge of epochal proportions. On a planet which will soon house 8 billion people, the greatest challenge is to meet every day the growing demand for energy at sustainable cost, while avoiding the creation of disruptive environmental imbalances. It is no secret that over the past several decades, the world has dramatically changed, largely thanks to the contribution of fossil fuels (e.g., coal, oil, and natural gas) and the massive contamination of the environment by wastes. Fossil fuels have provided us with cheap and convenient energy which we use for heating and electric power generation, and have been widely used as transportation fuels and also for chemical production. With a continuous population increase and expansion of economies, global energy consumption is increasing rapidly, and so is waste generation, whereas cheap fossil fuels as nonrenewable sources are rapidly depleting. Moreover, their massive utilization has also caused many problems such as environmental damage (e.g., ozone depletion, global warming) associated with various emissions. Greenhouse gas (GHG) emissions resulting from the provision of energy services have contributed significantly to the historic increase in atmospheric GHG concentrations. Recent data confirm that consumption of fossil fuels accounts for the majority of global anthropogenic GHG emissions (International Energy Outlook, 2018). Therefore, finding effective, sustainable solutions to combat the effects of anthropogenic global warming is the greatest challenge faced by the global community in the 21st century. To this end, a massive change in the energy supply structure is required in the future to meet the growing demand for energy, while reducing the impact on the environment. In this regard, several scenarios have been forecast by different institutions based on different perspectives and techniques (Energy and Climate Change Committee, 2016).

According to the International Energy Outlook (IEO) 2017 published by the International Energy Agency (IEA), world energy consumption will increase by 28% between 2015 and 2040, with more than half of the increase attributed to non-Organization for Economic Cooperation and Development (OECD) countries (i.e., those countries outside the OECD, including China and India), where strong economic growth drives increasing demand for energy (International Energy Outlook, 2018). Fig. 1.1 presents world marketed energy consumption from different fuel sources over the 2015–40 projection period. Although renewable energy and nuclear power are the world’s fastest-growing forms of energy, fossil fuels are expected to continue to meet much of world’s energy demand, sharing more than 80% of world marketed energy consumption. Among them, liquid fuels remain the world’s largest source of energy due to their importance in the transportation and industrial end-use sectors, whereas their share is predicted to decrease from 33% in 2015 to 31% in 2040, as the supply is projected to be driven by high and fluctuating world oil prices.

Figure 1.1 World energy consumption by fuel type, 1990–2040 (quadrillion Btu) (International Energy Outlook 2018 - IEO 2018).

Natural gas is the world’s fastest-growing fossil fuel, increasing by 1.4%/year, compared with liquid gas at 0.7%/year growth and virtually no growth in coal use (0.1%/year). The study shows that coal is increasingly replaced by natural gas, renewables, and nuclear power in electricity generation, even in countries such as China, where coal has always been the primary source of energy.

Similarly, natural gas continues to be an attractive fuel for the electric power and industrial sectors in many countries. These two uses account for almost 75% of the projected increase in total consumption between 2015 and 2040. This is mostly because of low capital costs, favorable heat rates, and relatively low fuel costs. Furthermore, the new limits for sulfur content of marine fuels will lead to a greater use of liquefied natural gas (LNG) as a bunkering fuel compared to traditional liquid fuels (Kumar et al., 2011).

Along with nuclear, the other fastest-growing source of world energy is renewable power. Renewables are generally defined as those energy resources which are naturally replenished on a human timescale such as sunlight, wind, biomass, tides, waves, geothermal heat, etc., and do not directly contribute to GHG accumulation in the atmosphere. In the reference case, the renewables share of total energy use rises from 12% in 2015 to 17% in 2040. A combination of these two fast-growing markets (i.e., natural gas and renewables), along with improved technologies and better waste management solutions, are some of the proposed solutions that could soon reduce the dependency on traditional fossil sources, leading to a slow but consistent decarbonization of the world energy sector.

Decarbonization pathways

Sustainable development is currently considered the best approach to address the complex and interrelated threats that the world is facing today (Waas et al., 2010), including both a secure energy supply and environmental pressure (Tagliaferri, 2016). The energy transition toward a new energy model based on a CO₂-emission-free society is one of the most critical challenges for our global community. It implies the integral transformation of productive processes at all levels such as energy production (shifting rapidly from fossil to renewable energy sources), energy vectors (heat, electricity, gas, etc.), and final utilization (industry, transportation, heating, etc.). Such transformation must include new advance technologies to make possible a transition from an energy system sustained by centralized energy generation toward a distributed one, in which the clear difference between energy producers and consumers becomes less evident (Abánades, 2018).

The emissions from the energy sector strongly depend on the sources and technologies used to supply the energy. Therefore, energy policies must play a major part in the modification of the energy mix in order to globally and locally decrease the impact of this sector. This is deemed high priority for a balanced development of the energy supply, as specified by the “energy trilemma.” This concept is most usually used to describe a balance between energy security, social impact, and environmental sensitivity, which are often presented as conflicting aspects of energy production (World Energy Council, 2016) (Fig. 1.2).

Figure 1.2 The energy trilemma.

For example, focusing on GHG reduction may impede energy security and access, while focusing on increasing affordability may impact energy security and environmental sustainability (Tagliaferri, 2016). In order to maintain the delivery of a balanced energy system in line with the trilemma, each country has still to face a number of substantial challenges for the future:

• • The population worldwide is continue increasing, with a growth of more than 25% by 2050 [more than 9.8 billion people are expected to be living in the world in 2050 (World Bank, 2013)]. Hence, the challenge to deliver an affordable energy supply is self-evident.
• • The energy infrastructure is rapidly ageing. In Europe, for example, many old coal power plants will be forced to close and will be replaced by lower-carbon and more efficient energy sources and technologies. Energy efficiency will of course be a very important part of the overall strategy, whatever route is followed; in particular it can help reduce investment costs. But energy efficiency on its own (i.e., without fuel switching) will not be enough to meet the emissions reduction targets.
• • Currently most deve...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• Preface
• 1. The role of waste and renewable gas to decarbonize the energy sector
• 2. Waste as a feedstock: technical information and commercial availability
• 3. Waste collection, sorting, and pretreatment
• 4. Storage and feedstock preparation
• 5. Anaerobic digestion: an engineered biological process
• 6. Organic waste streams upgrading for gasification process optimization
• 7. Waste gasification processes for SNG production
• 8. Gas cleaning for waste applications (syngas cleaning for catalytic synthetic natural gas synthesis)
• 9. Methane synthesis
• 10. Membranes utilization for biogas upgrading to synthetic natural gas
• 11. Methane from waste: Thermal and biological technologies compared under a life cycle assessment perspective
• 12. Bio-synthetic natural gas for heating and transport applications: the UK case
• 13. Biomass anaerobic digestion and gasification in non-OECD countries—an overview
• 14. Scandinavian biogas Södertörn—Sweden
• 15. Production of biogas/bioSNG from anaerobic pretreatment of milk-processing wastewater
• 16. Examples of thermochemical and biological treatment technologies for sustainable waste management in China
• 17. The GoBiGas plant
• 18. The GoGreenGas case in the UK
• Index