Hybrid Systems and Multi-energy Networks for the Future Energy Internet

By Yu Luo, Yixiang Shi and Ningsheng Cai

Hybrid Systems and Multi-energy Networks for the Future Energy Internet provides the general concepts of hybrid systems and multi-energy networks, focusing on the integration of energy systems and the application of information technology for energy internet. The book gives a comprehensive presentation on the optimization of hybrid multi-energy systems, integrating renewable energy and fossil fuels. It presents case studies to support theoretical background, giving interdisciplinary prospects for the energy internet concept in power and energy. Covered topics make this book relevant to researchers and engineers in the energy field, engineers and researchers of renewable hybrid energy solutions, and upper level students.

• Focuses on the emerging technologies and current challenges of integrating multiple technologies for distributed energy internet
• Addresses current challenges of multi-energy networks and case studies supporting theoretical background
• Includes a transformative understanding of future concepts and R&D directions on the concept of the energy internet

• Language: English
• Publisher: Academic Press
• Release date: Aug 28, 2020
• ISBN: 9780128191859

Yu Luo

Yu Luo, Associate Professor, National Engineering Research Center of Chemical Fertilizer Catalyst, Fuzhou University. His research interests are distributed energy network systems, CHP systems, flame fuel cells and exergy analysis.

Book preview

Hybrid Systems and Multi-energy Networks for the Future Energy Internet

Yu Luo

National Engineering Research Center of Chemical Fertilizer Catalyst (NERC-CFC), Fuzhou University, Fujian, China

Yixiang Shi

Department of Energy and Power Engineering, Tsinghua University, Beijing, China

Ningsheng Cai

Department of Energy and Power Engineering, Tsinghua University, Beijing, China

Contents

Cover

Title page

Copyright

Acknowledgments

Chapter 1: Introduction

Abstract

1.1. World energy

1.2. Electricity

1.3. Renewable energy

1.4. Carbon dioxide emission

1.5. Summary

Chapter 2: Distributed hybrid system and prospect of the future Energy Internet

Abstract

2.1. Introduction

2.2. Topology of distributed hybrid systems

2.3. Scales of distributed hybrid systems

2.4. Distributed energy networks

2.5. Prospect of the future Energy Internet

2.6. Summary

Chapter 3: Bridging a bi-directional connection between electricity and fuels in hybrid multienergy systems

Abstract

3.1. Introduction

3.2. Fuel cells for energy generation

3.3. Power-to-gas or power-to-liquid for energy storage

3.4. Reversible fuel cells

3.5. Summary

Chapter 4: High-efficiency hybrid fuel cell systems for vehicles and micro-CHPs

Abstract

4.1. Introduction

4.2. Hybrid fuel cell/battery vehicle systems

4.3. Fuel cell-based micro CHP or CCHP systems

4.4. Hybrid fuel cell vehicle: Mobile distributed energy system

4.5. Summary

Chapter 5: Stabilization of intermittent renewable energy using power-to-X

Abstract

5.1. Introduction

5.2. Power-to-gas systems

5.3. Power-to-liquid systems

5.4. Summary

Chapter 6: Ammonia: a clean and efficient energy carrier for distributed hybrid system

Abstract

6.1. Introduction

6.2. Ammonia-based energy roadmap

6.3. Current interest and projects on ammonia-based energy vector

6.4. Hybrid systems for ammonia production

6.5. Ammonia-fueled hybrid systems

6.6. Summary

Chapter 7: Power balance and dynamic stability of a distributed hybrid energy system

Abstract

7.1. Introduction

7.2. Dynamic system simulation platform

7.3. Renewable power integration and power balance

7.4. Novel criterion for distributed hybrid systems

7.5. Summary

Chapter 8: Applying information technologies in a hybrid multi-energy system

Abstract

8.1. Why information technologies are needed?

8.2. Block chain and energy transaction

8.3. Energy big data and cloud computing

8.4. Internet of Things applications

Chapter 9: Application and potential of the artificial intelligence technology

Abstract

9.1. Smart energy

9.2. Prediction for energy Internet

9.3. Control and optimization based on artificial algorithm

9.4. Swarm intelligence for complex energy networks

Index

Copyright

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Acknowledgments

The authors would like to appreciate the support and contribution of Prof. Lilong Jiang, the director of National Engineering Research Center of Chemical Fertilizer Catalyst (NERC-CFC) on Chapter 6. Prof. Lilong Jiang shared his insightful views, interdisciplinary thinking, and comprehensive vision, which help us open our mind and have a new understanding about the potentials of ammonia (NH3) as a clean and efficient energy carrier. The authors would also like to appreciate the contribution of Yi Zheng from the Department of Energy and Power Engineering, Tsinghua University on Chapters 8 and 9.

The authors would like to appreciate the support from the Beijing Natural Science Foundation Outstanding Youth Science Foundation Project (JQ18009), the National Youth Talent Support Program, and the National Basic Research Program of China (973 Program, 2014CB249201).

Chapter 1

Introduction

Yu Luoa

Yixiang Shib

Ningsheng Caib

a    National Engineering Research Center of Chemical Fertilizer Catalyst (NERC-CFC), Fuzhou University, Fujian, China

b    Department of Energy and Power Engineering, Tsinghua University, Beijing, China

Abstract

This chapter is the introduction of this book. In this chapter, we will briefly review the current energy status and the expected energy structure in the coming decades from EIA and BP. Finally, we describe the framework of this book and the main content of each chapter.

Keywords

word energy

renewable energy

carbon dioxide emission

energy structure

electrification

1.1. World energy

Energy is one of the most significant basis of human activities. The history of energy transitions reflects the history of the development of human society. As science and technologies develop rapidly, industrialization implements and the human population booms, an increasing amount of energy is needed to produce food, offer clean potable water, process raw materials, support communications, lighting and mobile devices, etc., in order to satisfy the requirement for comfortable and diversified lifestyles.

The original form of energy is a resources existing in nature, which is called as the primary energy sources. The common primary energy sources include fossil fuels, hydro energy, solar energy, wind energy, nuclear energy, etc. Table 1.1 summarizes the global primary energy consumption by energy source in 2018 and the expected one in 2050 released by Energy Information Administration (EIA) from US Department of Energy [1]. In 2018, global energy structure is still dominated by fossil fuels, that is, coal, natural gas, petroleum, etc. The use of fossil fuels accounts for more than 80% of global primary energy consumption, reaching 5.23 × 10¹¹ GJ. About 15% of global primary energy consumption, that is, 9.8 × 10¹⁰ GJ, is attributed to renewable energy, and nuclear energy accounts for less than 5% of global primary energy consumption (3.0 × 10¹⁰ GJ). According to the EIA’s prediction [1], global primary energy consumption in 2050 will rise by almost a half to 9.53 × 10¹¹ GJ, in which renewable energy will rise rapidly by ∼3% per year in the coming decades. In 2050, the global renewable energy consumption is expected to climb up by 2.68 folds to 2.63 × 10¹¹ GJ, exceeding any other primary energy sources. Coal, natural gas, and liquid fossil fuels (represented by petroleum) are expected to rise only by 11%, 43%, and 22% to 1.88 × 10¹¹ GJ, 2.08 × 10¹¹ GJ and 2.54 × 10¹¹ GJ, respectively. Relatively slow increase leads to the shares in total primary energy consumption dropping by 6.3%, 0.3%, and 5.5%. Even so, fossil fuels are still expected to account for almost 70% of global primary energy consumption in 2050. Overall, carbon-free energy sources are playing a more and more significant role in the future energy consumption, but fossil fuels will still dominate in the global energy structure.

Table 1.1

EIA also summarized the global end-use energy consumption by sector and end-use fuel in 2018 and the expected one in 2050 as shown in Table 1.2 [1]. Whenever at present or in the future, industrial sector always accounts for more than a half of end-use energy consumption. Transportation sector slightly exceeds one quarter of global end-use energy consumption. The remaining end-use energy consumption (less than one quarter) is attributed to building sector (residential and commercial). At present, the end-use energy consumption is mainly dominated by fossil fuels involving liquid fuels, natural gas and coal, accounting for over 77% of global end-use energy consumption. Among these fossil fuels, liquid fuels are the main fuel or feedstock of transportation and industrial sectors owing to high energy density, acceptable cost and appropriate chemical properties, accounting for 42% of global end-use energy consumption. Coal is still an indispensable industrial end-use fuel used in energy-intensive industrial processes like metallurgy, cement production, etc. Especially in China, coal is still a major energy form widely used in centralized chemical plants. Meanwhile, most of electricity, heat and cold generation are still relied on large-scale coal-fueled power plants, combined heat and power (CHP) plants and combined cooling, heat, and power (CCHP) plants. Since the Second Industrial Revolution, electricity (secondary energy) has been widely used in the residential and commercial buildings. In end-use side, electricity consumption reached 8.2 × 10¹⁰ GJ, 17.4% of global end-use energy consumption. With renewable energy blooming and energy conversion technologies and information technologies developing, energy systems are transforming in the distributed (flexible-scale) and electrification direction. Electricity is expected to play a more and more significant role in the industrial and transportation sectors. In 2050, electricity is expected to account for 22.6% of global end-use energy consumption, about 5% higher than that in 2018. Despite renewable energy sources only account for ∼5% of end-use energy consumption at present or in the coming several decades, electricity produced from renewable energy sources will grow significantly according to EIA’s data in Table 1.1.

Table 1.2

1.2. Electricity

Table 1.3 reveals the global end-use electricity consumption by sector in 2018, as well as the expected one in 2050 reported by EIA [1]. Currently, global electricity use is estimated to be 22.8 trillion kWh, in which industrial sector consumes 10.4 trillion kWh electricity, dominating the global electricity consumption (accounting for ∼46%). Residential sector consumes almost 30% of global electricity use, that is, 6.7 trillion kWh, and commercial sector consumes ∼5.2 trillion kWh, almost 23% of global electricity use. As expected, global electricity use will rise by 80% to 41.1 trillion kWh. Electricity use of industrial sector will rise by 43% to 14.9 trillion kWh. The growth rate of industrial electricity use is lower than that of global electricity use, thus, the share of industrial electricity is expected to drop by 10 points of percentage to 36%. The electricity use from residential sector is expected to soar up remarkably by 2.2 folds to almost 14.7 trillion kWh. The share of residential electricity will reach almost 36%, equivalent to that of industrial electricity. The electricity consumed by commercial sector is expected to rise by 76% to ∼9.1 trillion kWh, the share of which slightly drops by 0.6%–22.1%. The electricity used by transportation sector is expected to be almost triple of that in 2018 due to the development of electric vehicles. However, the share of transportation sector in electricity use is expected to be still no more than 6%. In the coming future, much more electricity is needed to meet diverse lifestyles of human beings. Therefore, distributed power generation could increase to meet the end-use electricity demand from residences, commercial buildings, electric vehicles, etc.

Table 1.3

1.3. Renewable energy

IEA’s reports indicate that in 2010, electricity generation from renewable energy accounted for ∼21% of global electricity generation [1], and the share rose to 24% in 2016 [2]. As IEA’s 2019 report expects [1], in the period from 2018 to 2050, electricity generated from renewable energy will rise by 3.6% per year in average, faster than electricity generated from any other energy resources. Electricity generation from renewable energy is expected to be ∼8.2 trillion kWh in 2020, and increase to ∼21.7 trillion kWh in 2050. The ratio of electricity generated from renewable energy to global electricity generation will further rise to ∼31% in 2020, and soar up to ∼49% in 2050. Table 1.4 shows the expected electricity generation from various renewable energy sources including hydroenergy, wind energy, solar energy, geothermal energy, etc, in 2020 and 2050 [1]. Until 2020, electricity generated from hydroenergy still dominates renewable energy-driven electricity generation, and wind energy and solar energy will share ∼22% and ∼16% of global renewable energy used for electricity generation, respectively. Nevertheless, in 2050, renewable energy-driven electricity generation is expected to be dominated by solar energy, wind energy and hydroenergy, in which hydroenergy is expected to share less than solar and wind energy in global renewable energy used for electricity generation. Solar energy is expected to be the largest renewable energy sources used for electricity generation, that is, ∼38%. The share of wind energy could be slightly lower than that of solar energy, ∼31%. Almost 70% of renewable energy-driven electricity generation is expected to come from solar energy and wind energy. Considering the features of intermittency and fluctuation, the wide application of solar energy and wind energy needs scale-flexible and operation-flexible energy storage systems to balance renewable energy output and end-use electricity demand. For efficient electricity generation or co-generations, distributed generation systems are also necessary. Therefore, distributed hybrid energy systems are one of the essential technologies for large-scale utilization of renewable energy sources.

Table 1.4

1.4. Carbon dioxide emission

Current fossil fuel-based energy structure results that carbon dioxide emissions are bound to an inevitable issue. According to the statistical data and expected data from BP [3], Fig. 1.1 shows annual CO2 emissions by sector in 1995 and 2017, and their expectation in 2040. From 1995 to 2017, annual CO2 emissions increased from 22 Gt by 54% to 34 Gt. This increase should be mainly attributed to power and transport sectors, which have caused that CO2 emission rose by 5.4 Gt and 3.3 Gt, respectively. BP also presented two scenarios to predict CO2 emissions in 2040 expectation, named as evolving transition (ET) scenario and rapid transition (RT) scenario, respectively. In the ET scenario, population, gross domestic product (GDP), energy use, policies, technologies, etc., evolves in a manner and speed seen over the recent past [3]. The RT scenario reveals the most optimistic prediction, where all the low-carbon scenarios in all the sectors have been considered to minimize carbon dioxide emissions. In the ET scenario, annual total carbon emission in 2040 is ∼7% higher than that in 2017, revealing a much slower growth rate than that before 2017. However, this prediction is still far away from the realization of Paris climate goals. Therefore, much more efforts should be paid on CO2 emission reduction. Among all the sectors, power sector was expected to be the biggest contributor of CO2 emission in the coming several decades. In the RT scenario, the annual total CO2 emission was expected to be almost a half of that in 2017, which is mainly attributed to significant reduction in power sector (reducing by 75%) and industrial sector (reducing by 75%).

Figure 1.1   CO2 emissions by sector and their 2040 expectation in ET and RT scenarios. Data from BP Energy Outlook: 2019 edition [3].

To promote CO2 emission reduction, we should pay our efforts on three aspects, that is, resource efficiency improvement, development of low-carbon energy sources and carriers, and carbon storage and removal [3]. The crucial point for CO2 emission reduction is to utilize low-carbon even zero-carbon energy sources and develop decarbonized power. On one hand, decarbonized power needs more renewable power, nuclear power, or power generated from fossil fuel-based power plants with carbon capture, utilization, and storage (CCUS). On the other hand, novel clean energy carriers like hydrogen and bioenergy are suitable for meeting energy demand from end-use sides. Meanwhile, efficiency enhancement in energy systems can also help to reduce CO2 emission. To approach to the goals in RT scenario, renewable power is needed to scale up, and advanced low-carbon technologies are in urgent demand.

1.5. Summary

To develop low-carbon and energy-saving energy roadmap, a series of supporting technologies are required, such as energy storage technology, demand side response technology, grid interconnections and multi-energy networks, energy use electrification, and digitalization. As renewable energy is playing a more and more significant role in the energy structure, energy systems tend to be more scale-flexible and decentralized. Therefore, these supporting technologies will be combined to develop novel distributed hybrid systems, and further promote the formation of the future Energy Internet.

In this book, we aim to introduce the concept of the distributed hybrid systems, review a part of novel technologies applicable in the distributed hybrid systems, and share our understandings on the future combination between energy technologies and information technologies. This book consists of 10 chapters. In this chapter (Chapter 1), we briefly reviewed current energy status and the expected energy structure in the coming decades from EIA and BP. In Chapter 2, we will present a brief review on the status of the distributed hybrid systems and supporting technologies. In Chapter 3–7 promising low-carbon energy carriers and their related energy conversion devices, as well as system layout, typical performance and system dynamics of advanced distributed hybrid systems. In Chapter 8 and 9, we will extend to energy networks and discuss their combination with advanced information technologies, especially the artificial intelligence (AI) technologies, and share our perspective on the future Energy Internet. Finally, we will outlook the opportunities and challenges for the distributed hybrid systems and the future Energy Internet.

References

[1] DOE-EIA. International Energy Outlook 2019 with projections to 2050. 2019. <https://www.eia.gov/outlooks/ieo/pdf/ieo2019.pdf>.

[2] Gür TM. Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage. Energ Environ Sci. 2018;11:2696–2767.

[3] BP. BP Energy Outlook: 2019 edition. <https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/energy-outlook/bp-energy-outlook-2019.pdf>.

Chapter 2

Distributed hybrid system and prospect of the future Energy Internet

Yu Luoa

Yixiang Shib

Ningsheng Caib

a    National Engineering Research Center of Chemical Fertilizer Catalyst (NERC-CFC), Fuzhou University, Fujian, China

b    Department of Energy and Power Engineering, Tsinghua University, Beijing, China

Abstract

Increasing energy demand and environmental issues urge human beings to develop and utilize energy sources in a more sustainable pathway. Distributed hybrid system (DHS) playing an important role in the future energy structure due to the features of user-oriented, flexible scale, multienergy co-generation, and ability in individual customization. In this chapter, we introduce the basic topology, applications, and current status of DHS. According to the functions of different energy devices, we divide DHS into four subsystems: energy generation subsystem, energy storage subsystem, energy recovery subsystem, and energy end-use subsystem. For each subsystem, energy devices commercially available or under research and development are reviewed. The connection between DHS and DHS or DHS and energy transmission networks form a complex distributed energy network (DEN). DEN is considered as a prototype of the future Energy Internet. Hierarchical control strategies are in demand to meet different requirements in device-level, DHS-level, and DEN-level. Finally, we look ahead to the trend of DHS and discuss the prospect of the future Energy Internet.

Keywords

distributed hybrid system

renewable energy

energy storage

multienergy flow

distributed energy network

Energy Internet

2.1. Introduction

Increasing energy demand and environmental issues urge human beings to develop and utilize energy sources in a more sustainable pathway. Traditional fossil fuel-based energy structure needs to be optimized by integrating clean energy sources such as renewable energy. Traditional fossil fuel-based centralized energy system (CES) generates electricity using several large-scale generation units, and then transmits electricity to domestic, commercial, and industrial consumers [1]. In CES, the energy devices are generally with large capacities (∼100 MW) and the energy flows are unidirectional [2]. However, CES requires high stability and reliable power integration, which conflicts with the intermittency and fluctuation of renewable energy including wind energy, solar energy and more, and further limits its penetration. To alleviate this conflict and utilize various energy sources adequately, developing distributed energy systems (DESs) is a feasible approach. Fig. 2.1 compares the schematics of centralized and DESs [1]. Differently from large-scale CESs, DESs have the following features:

1. User-oriented: DES serves local energy consumers and directly orients to the local energy demands. DES usually locates near the users, which reduces energy losses and economic costs during the transportation.

2. Flexible scale: The size of DES is flexible and up to the energy consumers. Typically, DES can vary from ∼20 W (residential-use generators) to ∼10 MW (biomass generation) [3].

3. Multienergy input and output: Development of energy conversion technology and human society leads to the diversification of energy sources and demands. DES is an open energy system, and capable of various energy input and output to utilize energy sources more efficiently and meet diverse energy demands. Bi-directional energy flows are also available in DES.

4. Ability in individual customization: Diverse consumer demands could expand the functions of DES by combining various technologies from multiple fields such as energy engineering, information engineering, automotive engineering, chemical engineering, etc. The evaluation criterion of DES is varying with the demand on efficiency, reliability, economic costs, environmental impacts, and sustainability.

Figure 2.1   Schematic of centralized and distributed energy systems. From Ref. [1]. Copyright 2017 Elsevier Ltd.

Based on the above features, DES can achieve energy cascade utilization, feasible sizing, and operation to improve the overall efficiency and lower the environmental pollution, particularly for co-generation of electricity, heat, and cold [4,5]. Fig. 2.2 shows the statistic or planned annual installed capacity, share of capacity additions and investments in DES in 2000, 2012, and 2020 [1]. The newly installed DES capacity soared from 47 GW by 202% to 142 GW, the share of capacity additions from 21% to 38%, and the corresponding investments from 30 billion dollars by 4 folds to 150 billion dollars in the worldwide over the period from 2000 to 2012. As projected, DES will continue growing. The newly installed DES capacity in 2020 will reach 200 GW, 41% of total annual capacity additions, and the annual investments will increase to 206 billion dollars.

Figure 2.2   Annual installed capacity, share of capacity additions and investments in DES worldwide. From Ref. [1]. Copyright 2017 Elsevier Ltd.

Long distance electricity transmission is made feasible by increasing voltage, thus decreasing transportation losses [6]. However, heat and cold are transported through a certain working medium like water. Heat with higher temperature or cold with lower temperature results in higher thermal losses and lower exergy efficiency during the transportation. The use of water as the transport medium of thermal energy is limited in temperature range of <300 °C and transport distance of <10 km [7]. Consequently, DES can avoid the issue in long distance transmission of heat and cold and feasibly select the device capacity according to local energy demands. Besides, centralized plants aim to meeting the common energy demands for most consumers. DES is designed according to the oriented users, hence, can specifically consider some specific requirements. Particularly, off-grid DES can provide a feasible option to solve the power supply in rural or other remote areas where the power grid is hard to cover. Moreover, faster response of DES leads to a more flexible control and regulation, hence, DES can decouple intermittent renewable energy and power