Category: Flywheels

New Book: ‘Water, Energy, and Environment – A Primer’

After a long hiatus from blogging while I worked on a new book, I am pleased to announce that the book ‘Water, Energy, and Environment – A Primer’ will be published by International Water Association Publishing (IWAP) on February 18th (2019). It will be available in both printed and digital form, and the digital version will be downloadable for free as an Open Access (OA) document.

To access the free digital version go to IWAP’s OA website on Twitter: https://twitter.com/IWAP_OA.

Attached below is front material from the book, its preface and table of contents. Designed to serve as a basic and easily read introduction to the linked topics of water, energy, and environment, it is just under 200 pages in length, a convenient size to throw into a folder, a briefcase, or a backpack. Its availability as an OA document means that people all over the world with access to the internet will have access to the book and its 10 chapters.

With the completion of the book I plan to return to a regular schedule of blogging.
…………………………..
Contents
Preface ………………………………….. xi
Acknowledgement ……………………….. xv
Acronyms ……………………………… xvii
Epigraph ……………………………….. xxi
Chapter 1
Water and its global context …………………. 1
1.1 Earth’s Water Resources . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Saline Water and Desalination Processes . . . . . . . . . . . 2
1.3 Energy Requirements and Costs of Desalination . . . . . 5
1.4 Demand for Freshwater . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 Implications of Limited Access to Freshwater . . . . . . . . . 9
1.6 Actions to Increase Access to Freshwater . . . . . . . . . . 10
1.7 Gender Equity Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 2
Energy and its global context ……………….. 13
2.1 Energy’s Role in Society . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Energy Realities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 What is Energy? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.4 Energy Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.1 Important questions . . . . . . . . . . . . . . . . . . . . . . . 18
2.4.2 How is energy used? . . . . . . . . . . . . . . . . . . . . . . 18
2.4.3 Electrification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 3
Exploring the linkage between water
and energy ……………………………….. 23
3.1 Indirect Linkages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2 The Policy Linkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3 The Conundrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4 Addressing the Conundrum . . . . . . . . . . . . . . . . . . . . . . . 26
3.5 The Need for Partnership . . . . . . . . . . . . . . . . . . . . . . . . . 27
Chapter 4
Energy production and its consequences for
water and the environment …………………. 29
4.1 Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 More on Climate Change . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Environment and Religion . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.1 The theocentric worldview . . . . . . . . . . . . . . . . . 33
4.3.2 The anthropocentric worldview . . . . . . . . . . . . . 34
4.3.3 Other worldviews . . . . . . . . . . . . . . . . . . . . . . . . . 34
Chapter 5
Energy options ……………………………. 37
5.1 Fossil Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.2 Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.3 Geothermal Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.4 The Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.5 Energy Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.5.1 Energy demand . . . . . . . . . . . . . . . . . . . . . . . . . . 40
vi Water, Energy, and Environment – A Primer
5.5.2 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.5.3 Saving energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.5.4 Accelerating implementation . . . . . . . . . . . . . . . 43
5.5.5 Energy Star . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.5.6 The lighting revolution . . . . . . . . . . . . . . . . . . . . . 45
5.5.7 Energy efficiency in buildings . . . . . . . . . . . . . . . 48
5.5.7.1 Zero energy buildings . . . . . . . . . . . . . 48
5.5.7.2 Electrochromic windows . . . . . . . . . . . 52
5.6 Energy Efficiency in Industry . . . . . . . . . . . . . . . . . . . . . . 54
5.7 Energy Efficiency in Transportation . . . . . . . . . . . . . . . . 56
Chapter 6
Fossil fuels ………………………………. 61
6.1 Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6.1.1 Carbon capture and sequestration . . . . . . . . . . 63
6.1.2 A conundrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.2 Petroleum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.2.1 Oil spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.2.2 Peak oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.3 Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.3.1 Methane hydrates . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.3.2 Fracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Chapter 7
Nuclear power ……………………………. 85
7.1 Nuclear Fission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
7.1.1 Fission fundamentals . . . . . . . . . . . . . . . . . . . . . . 85
7.1.2 Introduction to nuclear issues . . . . . . . . . . . . . . . 87
7.1.3 Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
7.2 Nuclear Fusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
7.2.1 Fusion fundamentals . . . . . . . . . . . . . . . . . . . . . . 91
7.2.2 Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.2.3 Barriers to Fusion . . . . . . . . . . . . . . . . . . . . . . . . . 94
7.2.4 Pros and cons . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.2.5 Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Chapter 8
Renewable energy ………………………… 97
8.1 The Sun’s Energy Source and Radiation
Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
8.2 Direct Solar Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
8.2.1 Photovoltaics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
8.2.2 Concentrating solar power (CSP) . . . . . . . . . . 108
8.2.2.1 Power tower . . . . . . . . . . . . . . . . . . . . 109
8.2.2.2 Linear concentrator . . . . . . . . . . . . . . 110
8.2.2.3 Dish engine . . . . . . . . . . . . . . . . . . . . . 111
8.2.2.4 CSTP history . . . . . . . . . . . . . . . . . . . 112
8.2.2.5 Advantages and disadvantages . . . 112
8.2.2.6 Thermal storage . . . . . . . . . . . . . . . . . 113
8.2.2.7 Current status . . . . . . . . . . . . . . . . . . . 114
8.2.2.8 Concentrating photovoltaics (CPV) . 115
8.3 Solar Power Satellite (SPS) System . . . . . . . . . . . . . . 116
8.4 Hydropower and Wind Energy . . . . . . . . . . . . . . . . . . . 119
8.4.1 Hydropower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
8.4.2 Wind energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
8.4.2.1 Onshore wind . . . . . . . . . . . . . . . . . . . 121
8.4.2.2 History . . . . . . . . . . . . . . . . . . . . . . . . . 124
8.4.2.3 An onshore limitation . . . . . . . . . . . . . 124
8.4.2.4 Offshore wind . . . . . . . . . . . . . . . . . . . 125
8.5 Biomass Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.5.1 Sources of biomass . . . . . . . . . . . . . . . . . . . . . . 129
8.5.2 Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.5.3 Biofuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
8.5.4 Algae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
8.5.5 Biochar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.5.6 The future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.6 Geothermal Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
8.6.1 Sources of geothermal energy . . . . . . . . . . . . . 134
8.6.2 Manifestations of geothermal energy . . . . . . . 135
8.6.3 Uses of geothermal energy . . . . . . . . . . . . . . . . 135
8.6.3.1 Geothermal power generation . . . . . 136
8.6.3.2 Ground-source heat pumps . . . . . . . 138
8.6.4 An unusual source of geothermal energy . . . . 140
Ocean Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
8.7.1 Wave energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
8.7.1.1 Wave energy conversion
devices . . . . . . . . . . . . . . . . . . . . . . . . 142
8.7.1.2 Potential and pros and cons . . . . . . . 143
8.7.2 Ocean current energy . . . . . . . . . . . . . . . . . . . . 144
8.7.3 Tidal energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
8.7.3.1 Barrage . . . . . . . . . . . . . . . . . . . . . . . . 146
8.7.3.2 History . . . . . . . . . . . . . . . . . . . . . . . . . 147
8.7.3.3 Environmental impacts . . . . . . . . . . . 147
8.7.4 Ocean thermal energy conversion (OTEC) . . 147
8.7.4.1 Barriers . . . . . . . . . . . . . . . . . . . . . . . . 148
8.7.4.2 OTEC technologies . . . . . . . . . . . . . . 148
8.7.4.3 Other cold water applications . . . . . . 149
8.7.4.4 OTEC R&D . . . . . . . . . . . . . . . . . . . . . 149
Chapter 9
Energy storage …………………………… 151
9.1 Storage and Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
9.2 Types of Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.2.1 Traditional and advanced batteries . . . . . . . . . 153
9.2.1.1 Lead–acid . . . . . . . . . . . . . . . . . . . . . . 153
9.2.1.2 Sodium sulfur . . . . . . . . . . . . . . . . . . . 153
9.2.1.3 Nickel–cadmium . . . . . . . . . . . . . . . . . 154
9.2.1.4 Lithium-ion . . . . . . . . . . . . . . . . . . . . . 154
9.2.1.5 Supercapacitors . . . . . . . . . . . . . . . . . 155
9.2.2 Flow batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
9.2.3 Flywheels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
9.2.4 Superconducting magnetic energy
storage (SMES) . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.2.5 Compressed air energy storage (CAES) . . . . 159
9.2.6 Pumped storage . . . . . . . . . . . . . . . . . . . . . . . . . 160
9.2.7 Thermal storage . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.4 Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
9.5 Fundamental Change . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Chapter 10
Policy considerations …………………….. 165
10.1 Important Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
10.1.1 Is there a physical basis for understanding
global warming and climate change? . . . . . . 166
10.1.2 Is there documented evidence for global
warming and climate change? . . . . . . . . . . . . 168
10.1.3 Can global warming and climate change be
attributed to human activities, and what are
those activities? . . . . . . . . . . . . . . . . . . . . . . . . 170
10.1.4 What are the potential short- and long-term
impacts of global warming and climate
change with respect to water supply,
environment, and health? What is the
anticipated time scale for these
impacts? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
10.1.5 What can be done to mitigate the onset
and potential impacts of global warming
and climate change? . . . . . . . . . . . . . . . . . . . . 179
References ……………………………… 183
Index …………………………………… 189

……………………

Preface
This book springs from my strong conviction that clean water and clean energy are the critical elements of long-term global sustainable development. I also believe that we are experiencing the beginning of an energy revolution in these early years of the 21st century. Providing clean water requires energy, and providing clean energy is essential to reducing the environmental impacts of energy production and use. Thus, I see a nexus – a connection, a causal link – among water, energy, and environment. In recent years we have adopted the terminology of the water-energy nexus for the intimate relationship between water and energy, and similarly we can apply the term nexus to the close connections among water, energy, and environment. Thisuse of the term nexus can be, and has been, extended to include the related issues of food production and health. Dealing with, and writing about, a two-element nexus is difficult enough. In this book, I will limit my analysis and discussion to the three-element water -energy-environment nexus and leave the discussion of other possible nexus elements to those more qualified to comment.

This book also springs from my observation that while there are many existing books of a more-or-less technical nature on the three elements of this nexus, a book addressing each of them and their interdependencies in a college-level primer for a broad global and multidisciplinary audience would be valuable. Consideration of these and related issues, and options for addressing them, will be priorities for all levels of government. They will also be priorities for many levels of the
private sector in the decades ahead, both in developing and developed nations. A handbook-style primer that provides an easily read and informative introduction to, and overview of, these issues will contribute broadly to public education. It will assist governments and firms in carrying out their responsibilities to provide needed services and goods in a sustainable manner, and help to encourage young people to enter these fields. It will serve as an excellent mechanism for exposure of experts in other fields to the issues associated with the water-energy-environment nexus. Further, in addition to the audiences mentioned above, target audiences include economists and others in the finance communities who will analyze and provide the needed investment funds, and those in the development community responsible for planning and delivering services to underserved populations.
The book is organized as follows: the first chapter will be devoted to the concept of nexus and how the three elements, water, energy, and environment, are inextricably linked. This recognition leads to the conclusion that if society is to optimize their contributions to human and planetary welfare they must be addressed jointly. No longer must policy for each of these elements be considered in its own silo. Chapters 2 and 3 will be devoted to spelling out global contexts for water and energy issues, respectively. Chapter 4, on related environmental issues, will address the issues of water contamination, oil spills, fracking, radioactive waste storage, and global warming/
climate change. Chapter 5 will be a discussion of energy efficiency – i.e., the wise use of energy – and its role in limiting energy demand and its associated benefits. Chapter 6 will focus on the basics of fossil fuels – coal, oil, natural gas – which today dominate global energy demand. Chapter 7 will discuss nuclear-fission-powered electricity production, which today accounts for 10% of global electricity. It will also discuss the prospects for controlled nuclear fusion. Chapter 8 will discuss the broad range of renewable energy technologies – wind, solar,hydropower, biomass, geothermal, ocean energy – which are the basis of the now rapidly emerging energy revolution. Chapter 9 will discuss the closely related issue of energy storage. Finally, Chapter 10 will address
policy issues associated with water, energy, and environment, discuss policy history and options, and provide recommendations.

Looking Ahead 30-40 Years – A Risky Business

History has always been my favorite subject, starting in high school, and still constitutes a major part of my personal reading. Needless to say I have a strong interest in other topics as well, as attested to by my long career in science and engineering and education/mentoring activities with young people. What often fascinates me is looking back at how things have changed in the past, often in unexpected ways, and how people looking back in the decades ahead will put their perspectives on what we are doing today. This blog post is my attempt to flesh out these thoughts, while acknowledging the difficulty of looking into the future. If I look far enough into that future I will not be around to suffer the slings and arrows of projecting incorrectly, or collecting the kudos for projecting accurately. Nevertheless, it feels like a stimulating and challenging activity to undertake, and so here goes.

image

Let me start by going back seven decades to the 1940s when I was a young kid growing up in the Bronx and just beginning to form my likes and dislikes and develop opinions. My love for science fiction developed at that time and was probably a dead give-away of my future career interests. An important shaping event was the dropping of the first atomic bomb on Japan on August 6, 1945, an event that I still clearly remember learning about on the radio while sitting in the back seat of my parents’ car. Without a deep or much of any understanding at that time, I somehow sensed that the world had changed in that August moment. I still feel that way after many subsequent years of reading and studying.

The following decades saw several other unexpected and defining events: the addition of fusion weapons (hydrogen bombs) to our nuclear arsenals, commercial applications of controlled nuclear fission (nuclear submarines and nuclear-powered surface ships, and the first commercial nuclear power plant which was actually a land-based nuclear submarine power plant), development and emergence of the transistor as a replacement for vacuum tubes (first using germanium and then silicon), the development of the first solar cell at Bell Labs, the development and application of laser technology, the emergence of the information technology industry based on the heretofore abstract concepts of Boolean algebra (0s and 1s), and the increasing attention to a wide range of clean energy technologies that had previously been considered impractical for wide scale application – wind, solar, geothermal, ocean energy, fuel cells, advanced battery technologies, and a broad range of alternative liquid and gaseous fuels. Each in its own way has already changed and will further change the world in future decades, as will other technologies that we now only speculate about or cannot imagine. This is the lesson of history – it is difficult for most of us to look ahead and successfully imagine the future, and one of my earlier blog posts (‘Anticipating the Future: It Can Be Difficult’) discusses this topic. In the following paragraphs I speculate about the future with humility but also great anticipation. My only regret is that I will not live long enough to see most of this future unfold.

I will divide this discussion into two parts on which I have focused some attention and feel that I have some knowledge – medicine/health care, and energy. That leaves all too many aspects of the future that I don’t feel qualified to comment upon – e.g., what more will we learn about Amelia Earhart’s disappearance, Cuba’s possible participation in John Kennedy’s assassination, and the future of the tumultuous Middle East and the countries of the former Soviet Union. My primary focus in this post will be on the latter of the two parts, energy.

To help you understand my interest in medicine and health care I confess that at one point in my career, before committing to pursuing a PhD in physics, I gave serious consideration to attending medical school. During this period in the early 1960s I was a research scientist at Texas Instruments (TI) and was excited about the possibilities of miniature electronics which TI was pioneering in. I even suggested to my TI bosses that we undertake the application of transistors and sensors to artificial vision, but it was much too early for the company to make such a commitment. Today, 50 years later, that vision is being realized.

I also see great promise in the application of miniature electronics to continuous in-vivo diagnosis of human health via capsules that float throughout a human’s blood network, monitor various chemical components, and broadcast the results to external receivers. This will depend on low-powered miniature sensors and analysis/broadcast capability powered by long-lasting miniature batteries or an electrical system powered by the human body itself. Early versions are now being developed and I see no long-term barriers to developing such a system.

A third area in which I see great promise is the non-invasive monitoring of brain activity. This is a research area that I see opening up in the 21st century as we are beginning to have the sensitive tools necessary to explore the brain in detail. Given that the brain is responsible for so many aspects of our mental and physical health I expect great strides in the coming decades in using brain monitoring to address these issues.

The energy area is where I have devoted the bulk of my professional career and where my credibility may be highest – at least I’d like to think so. Previous blog posts address my thoughts on a wide range of current energy, water-energy, and related policy issues. Recognizing that changes in our energy systems come slowly over decades and sometimes unexpectedly, as history tells us, I will share my current thoughts on where I anticipate we will be in 30-40 years.

Let me start with renewable energy – i.e., solar, wind, hydropower, geothermal, biomass, and ocean energy. I have commented on each of these previously, but not from a 30-40 year perspective. Renewables are not new but, except for hydropower, their entering or beginning to enter the energy mainstream is a relatively recent phenomenon. Solar in the form of photovoltaics (PV) is a truly transformative technology and today is the fastest growing energy source in the world, even more so than wind. This is due to significant cost reductions for solar panels in recent years, PV’s suitability for distributed generation, its ease and quickness of installation, and its easy scalability. As soon as PV balance-of-system costs (labor, support structures, permitting, wiring) come down from current levels and approach PV cell costs of about $0.5-0.7 per peak watt I expect this technology to be widespread on all continents and in all developed and developing countries. Germany, not a very sunny country but the country with the most PV installed to date, has even had occasional summer days when half its electricity was supplied by solar. In combination with energy storage to address its variability, I see PV powering a major revolution in the electric utility sector as utilities recognize that their current business models are becoming outdated. This is already happening in Germany where electric utilities are now moving rapidly into the solar business. In terms of the future, I would not be surprised if solar PV is built into all new residential and commercial buildings within a few decades, backed up by battery or flywheel storage (or even hydrogen for use in fuel cells as the ultimate storage medium). Most buildings will still be connected to the grid as a backup, but a significant fraction of domestic electricity (30-40%) could be solar-derived by 2050. The viability of this projection is supported by the NREL June 2012 study entitled ‘Renewable Electricity Futures Study’.

Hydropower already contributes about 10% of U.S. electricity and I anticipate will grow somewhat in future decades as more low-head hydro sites are developed.

For many years onshore wind was the fastest growing renewable electricity source until overtaken recently by PV. It is still growing rapidly and will be enhanced by offshore wind which currently is growing slowly. However, I expect offshore wind to grow rapidly as we approach mid-century as costs are reduced for two primary reasons: it taps into an incredibly large energy resource off the coasts of many countries, and it is in close proximity to coastal cities where much of the world’s population is increasingly concentrated. In my opinion, wind, together with solar and hydro, will contribute 50-60% of U.S. electricity in 2050.

Other renewable electric technologies will contribute as well, but in smaller amounts. Hot dry rock geothermal wells (now called enhanced geothermal systems) will compete with and perhaps come to dominate traditional geothermal generation, but this will take time. Wave and tidal energy will be developed and become more cost effective in specific geographical locations, with the potential to contribute more in the latter part of the century. This is especially true of wave energy which taps into a large and nearly continuous energy source.

Biomass in the form of wood is an old renewable energy source, but in modern times biomass gasification and conversion to alternative liquid fuels is opening up new vistas for widescale use of biomass as costs come down. By mid-century I expect electrification and biomass-based fuels to replace our current heavy dependence on petroleum-based fuels for transportation. This trend is already underway and may be nearly complete in the U.S. by 2050. Biomass-based chemical feedstocks will also be widely used, signifying the beginning of the end of the petroleum era.

I expect that other fossil fuels, coal and natural gas, will still be used widely in the next few decades, given large global resources. Natural gas, as a cleaner burning fossil fuel, and with the availability of large amounts via fracking, will gradually replace coal in power plants and could represent 30-40% of U.S. power generation by mid-century with coal generation disappearing.

To this point I have not discussed nuclear power, which today provides close to 20% of U.S. electricity. While I believe that safe nuclear power plants can be built today –i.e., no meltdowns – cost, permanent waste storage, and weapons proliferation concerns are all slowing nuclear’s progress in the U.S. Given the availability of relatively low-cost natural gas for at least several decades (I believe fracking will be with us for a while), the anticipated rapid growth of renewable electricity, and the risks of nuclear power, I see limited enthusiasm for its growth in the decades ahead. In fact I would not be surprised to see nuclear power supplying only about 10% of U.S. electricity by 2050, and less in the future.

To summarize, my picture today of an increased amount of U.S. electricity generation in 2050 is as follows:

Generating Technology : Percent of U.S. Generation in 2050
nuclear: 5-10
coal: 0-5
Oil: 0
natural gas: 30-40
solar + wind + hydro: 50-60
other renewables: 5-10

I am sure that some readers of this post will take strong issue with my projections and have very different thoughts about the future. I welcome their thoughts and invite them to join me in looking ahead. As the title of this post acknowledges, looking ahead is risky business, but it is something I’ve wanted to do for a while. This seems as good a time as any to do so.

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Energy Storage: A Critical Link In the Renewable Energy Chain

An issue that has always grabbed my attention is the critical role I and others foresee for energy storage in the eventual widespread use of variable (intermittent) renewable energy sources such as wind and solar. In fact it was the focus of my first decision when I assumed responsibility for DOE’s renewable electricity programs in 1994. That decision was to establish a comprehensive storage program to complement the established generation programs – up until that point the only storage program was a small effort on underground hot water storage at a university in South Carolina (no doubt related to the fact that the Chairman of the relevant budget authorization subcommittee was from South Carolina). The new program, in addition to thermal storage, added battery storage and superconducting magnetic energy storage (SMES) – superconductivity was another of the programs I managed.

Energy storage is one of two critical renewable energy issues that I have always said I would ‘fall on my sword for’. The second is the need for a national smart grid that will allow renewable electricity generated in one part of the country to be shared with other parts. I have touched briefly on the energy storage topic in earlier blog posts; this post takes a much more detailed look at various storage options.

The need for storage to steady the output from a variable energy source is not new. In fact, in December 1861 the following words and illustration appeared in an agrarian newsletter:
“A Mighty Wind One of the great forces nature furnished to man without any expense, and in limitless abundance, is the power of the wind. Many efforts have been made to obtain a steady power from the wind by storing the surplus from when the wind is strong. One of the latest and simplest of these is illustrated in the accompanying engraving. A windwheel is employed to raise a quantity of iron balls, and then these balls are allowed to fall one by one into buckets upon one side of a wheel, causing the wheel to rotate, and thus to drive the machine.”

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If one substitutes water for the iron balls and attaches a generator to the rotating machine you have today’s system of pumped water storage and generation. A modern version of the 1861 system, using gravel instead of iron balls, is shown in the following sketch:

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Since the discovery of electricity generation using rotating coils of wire in magnetic fields by the British scientist Michael Faraday in 1820, people have sought ways to store that energy for use on demand. Without such storage, or use in some other way (e.g., to electrolyze water to create and store hydrogen, heat water, bricks or phase change materials that store heat , or refrigerate water to create ice) surplus electricity generation is lost. With modern societies increasingly dependent on energy services provided via use of electricity, the need for electricity storage technologies has become critical. This is especially true as more and more variable renewable energy enters the grid, to avoid grid destabilization. This can occur because electric power supply systems must balance supply and demand, and because demand is highly variable and hard to control the balancing is routinely achieved by controlling the output of power plant generators. If these generators are variable solar and wind, and their grid contribution becomes significant, achieving the balance is that much more difficult, and a means of stabilizing these variable outputs is needed.

There is also strong economic and social incentive for storing electricity in a localized, distributed manner. Today’s 100-year-old centralized utility business model, in which large central power plants deliver electricity to customers via transmission and distribution lines, includes the imposition of peak demand charges that can account for a significant fraction of a business’ or an individuals’ electricity bill. With the use of localized generation (e.g., PV panels on your roof), combined with storage at your site, these demand and peak charges can be reduced if not eliminated, and independence from the utility, to some degree, can be achieved. This reality is taking place in Germany (and coming to the U.S.) and threatening the utility business model in Germany to the extent that German utilities have gone into the solar-energy storage business. They now sell or lease or maintain roof-mounted PV and battery storage systems.

Today’s menu of devices that allow storage of surplus electricity for use at other times includes: solid state batteries and supercapacitors, flow batteries, flywheels, compressed air energy storage (CAES), and pumped hydropower. Hydrogen generated from any electricity source via electrolysis of water, and combusted or used in fuel cells, is, in many ways, the ultimate storage technology for surplus electricity. Flywheels, pumped storage, and fuel cells are discussed in earlier blog posts ; other storage technologies are discussed below.

Historically, electricity has been stored in lead-acid batteries, and this is still the dominant battery storage technology today in cars and elsewhere because of low cost, high power density, and high reliability. Disadvantages are low specific energy storage capacity, large size, high weight, and the need for an acid electrolyte. Lead is also a toxic material. Research to improve batteries has been underway for more than a century, and considerable progress has been made (e.g., improved lead-acid batteries that require no maintenance and recycling of used batteries to recover the lead), with considerable promise for further developments in the future.

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Most battery attention today is focused on lithium-ion batteries where cost and safety are prime concerns. Research into post lithium-ion batteries is also being actively pursued.
Lithium-ion batteries are widely used today because! “pound for pound they’re some of the most energetic rechargeable batteries available.” For example, it takes six kilograms of a lead-acid battery to store the same energy as one kilogram of a lithium-ion battery. Lithium-ion batteries (there is a variety of battery chemistries) also hold their charge well (losing about 5% per month), have no memory effect (therefore no need to fully discharge before recharging), can handle many hundreds of charge/discharge cycles, and have good ’round trip efficiency’. The story does have a negative side – lithium-ion batteries are sensitive to heat, can’t be fully discharged (thus requiring a computerized battery management system), are still costly (although costs are coming down), and certain chemical formulations can occasionally burst into flame if damaged or otherwise overstressed. One person making a big bet on lithium-ion batteries is Elon Musk, who has announced plans for a $5 billion battery factory, to provide lithium-ion batteries for his Tesla electric vehicles and other applications. Through such large scale production Musk hopes to reduce the cost of the batteries by 30 percent (to about $10,000 for a 60 kWh battery pack).

Supercapacitors store energy in electric fields and fill a gap between ordinary capacitors and rechargeable batteries. Their claim to fame is that they can be charged/discharged much more rapidly than batteries and can tolerate many more charge/discharge cycles. They are widely used as low current power sources for computer memories and in cars, buses, trains, cranes and elevators, including energy recovery from braking.

Redox (reduction/oxidation) flow batteries are large scale rechargeable energy storage systems that are on the verge of wide application in the electric utility sector. They are particularly well suited to storing large amounts of energy, e.g., the surplus energy created by hours of solar or wind power generation. The energy storage materials are liquids that are stored in separate tanks, and when energy is needed the liquids are pumped through a ‘stack’ where they interact to generate electricity. Many different chemical liquids have been tested for flow battery operation, with most current attention being focused on vanadium compounds which are expensive. Flow batteries also have relatively low round-trip efficiencies and response times. Because of the vanadium cost concern many other chemical possibilities are being evaluated.

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CAES (compressed air energy storage) utilizes surplus electricity to compress air to high pressures in large caverns, which can then be heated and released as needed to power expansion turbines that generate electricity. Such a CAES system has been operating successfully in Alabama since 1991, and gases other than air (e.g., carbon dioxide) can be used as well.

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SMES stores energy in the magnetic field of a circulating dc electrical current in a superconducting coil. The superconductor has no electrical resistance and the current continues indefinitely unless its energy is tapped by discharging the coil. A typical SMES device has two parts, a cryogenic cooler that cools the superconducting wire below its transition temperature at which it loses its electrical resistance, and power conditioning circuitry that allows for charging and discharging of the coil. Its advantages are ultra fast charge and discharge times, no moving parts, nearly unlimited cycling capability, and an energy recovery rate close to 100 percent. Disadvantages are cost of the wire, the need for continuous cooling, large area coils needed for appreciable energy storage, and the possibility of a sudden, large energy release if the wire’s superconducting state is lost. SMES devices are often used to provide grid stability in distribution systems and for power quality at manufacturing plants requiring ultra-clean power (e.g., microchip production lines). One MWh SMES units are now common and a twenty MWh engineering test model is being evaluated.

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To summarize, there are many energy storage options that work and tradeoffs are often required – e.g., among storage capacity, power capacity, round-trip efficiency, and most importantly cost. Lots of research is underway to reduce costs, given the large potential markets and the need to safely integrate variable renewable energy generation from solar and wind into the utility grid system. I have no doubt that cost-effective storage systems will soon be available, facilitating the needed rapid transition to a renewable electricity future.

Flywheels: A Way To Change the Utility Business Model?

Flywheels and other energy storage systems have the potential to change the way electric utilities operate. A while ago I put down my thoughts on flywheels in a 2010 article I share below in this blog.

The context for my thoughts is that the large central station model for utilities is changing as we move toward more decentralized power generation (think renewables). People are also beginning to react to the vulnerability of the current system to outages, whether accidental or deliberate, that leave thousands of people without power for extended periods of time.

Storage of energy, whether electrical or thermal, can reduce this vulnerability and allow greater use of variable (intermittent) renewable energy sources such as solar and wind. Pumped hydro, compressed air energy storage, and batteries have received the most attention to date. For batteries the major barriers have been insufficient storage capacity, purchase and maintenance costs, space requirements, and the inconvenience of replacement of heavy batteries.

Lead acid batteries have been used in cars, boats, buoys, aircraft and other applications requiring portable electricity sources for many years, and will be used for many years into the future. An interesting aspect of lead acid battery use was their powering of electrical vehicles in the early decades of the 20th century when electric vehicles were the dominant form of personal transportation. In fact, Mrs. Henry Ford drove an electric vehicle. This situation changed because of limited range then available with existing batteries and the advent of high energy density liquid petroleum fuels.

This may be changing today with the emergence of more energy dense and lighter lithium ion battery technologies, but cost is still a major consideration. While cheaper lithium ion cells are coming and lithium ion battery packs are being explored actively for a wide range of applications, including electric vehicles and utility power storage, I would like to suggest that flywheels may also have a role to play in our electric utilities’ future. This idea has been swirling around in my head for many years, and has been mentioned by others, but with the advent of advanced flywheels in recent years I believe it is time to take a serious look at using flywheels in individual homes.

An additional consideration is that as decentralized power systems such as solar roofs become more widely accepted, and utility intermediate- and peak-power sales are reduced, utilities are having to think about getting into the solar energy and energy storage businesses, as is already happening in Germany. I expect this to happen in the U.S. as well.

Using Flywheels to Supply Residential Electricity Demand (July 2010)

Flywheels have always appealed to me as an interesting and potentially widely useful energy storage technology. For many years I have thought about using flywheels at individual homes to supply residential electricity demand during waking hours, using less expensive utility electricity at night to recharge the flywheel (i.e., get it up to maximum rotational speed and stored energy). Limitations have been the physical stresses on flywheel components at the high rotational speeds needed to store appreciable amounts of energy (i.e., tens of kWh) and cost. The use of advanced carbon-fiber materials may now have addressed the first limitation, and cost reductions will be associated with large scale manufacturing of the devices (still to come). The purpose of this note is to explore the feasibility and stimulate discussion of such an approach ( a few others have discussed this possibility as well), which has the potential to reduce utility peak power demands, reduce consumer costs by taking consumers off the grid at peak periods, and transform the nature of utilities. It is offered as a personal thought and does not reflect my responsibilities at the U.S. Department of Energy (2013 note: from which I am now retired).

I start by looking at residential consumer demand. According to the U.S. Department of Energy’s Energy Information Administration: “In 2008, the average annual electricity consumption for a U.S. residential utility customer was 11,040 kWh, an average of 920 kilowatt-hours (kWh) per month. Tennessee had the highest annual consumption at 15,624 kWh and Maine the lowest at 6,252 kWh.” This corresponds to an average daily demand of 11,400/365 = 31.2 kWh. Flywheels that can store 25 kWh are commercially available today (see www.beaconpower.com), and it is not unreasonable to assume that slightly larger flywheels could be easily manufactured. Thus, the idea of a flywheel providing a residence’s daily electricity demand is not unreasonable.

How do flywheels work? To quote from the Beacon Power website (there are other flywheel manufacturers as well): “Flywheel energy storage works by accelerating a cylindrical assembly called a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel. The flywheel system itself is a kinetic, or mechanical battery, spinning at very high speeds to store energy that is instantly available when needed.

At the core of Beacon’s flywheel is a carbon-fiber composite rim, supported by a metal hub and shaft and with a motor/generator mounted on the shaft. Together the rim, hub, shaft and motor/generator assembly form the rotor. When charging (or absorbing energy), the flywheel’s motor acts like a load and draws power from the grid to accelerate the rotor to a higher speed. When discharging, the motor is switched into generator mode, and the inertial energy of the rotor drives the generator which, in turn, creates electricity that is then injected back into the grid. Multiple flywheels may be connected together to provide various megawatt-level power capacities. Performance is measured in energy units – kilowatt-hours (kWh) or megawatt-hours (MWh), indicating the amount of energy available over a given period of time.

Beacon’s Smart Energy 25 flywheel has a high-performance rotor assembly that is sealed in a vacuum chamber and spins between 8,000 and 16,000 rpm. At 16,000 rpm the flywheel can store and deliver 25 kWh of extractable energy. At 16,000 rpm, the surface speed of the rim would be approximately Mach 2 – or about 1500 mph – if it were operated in normal atmosphere. At that speed the rim must be enclosed in a high vacuum to reduce friction and energy losses. To reduce losses even further, the rotor is levitated with a combination of permanent magnets and an electromagnetic bearing.”

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An obvious issue associated with flywheels is catastrophic failure. With rotors moving at high rotational speeds and the flywheel structure experiencing large physical stresses, what would happen if a flywheel flew apart? The industry’s answer is that they’re designed for safety, which is probably correct, but people will need additional reassurance, at least for a while. Thus, my proposal would be to place the flywheel unit under garage or carport concrete floors with a removable protective cover, to allow maintenance as needed. Flywheels can also be shielded in other “containers” as well.

Issue #2 is how long does it take to charge up a flywheel at night from full discharge? First we note that there is an energy loss associated with charging/discharging flywheels, and round-trip efficiencies have routinely been quoted in the 70-85 percent range. Recent literature quotes over 90 percent, and for purposes of calculation I shall assume 85 percent as a reasonable number to start with. Thus, to have 31.2 kWh available for useful discharge we will have to supply 31.2/0.85 = 36.7 kWh to the flywheel. A dedicated 40-amp 220 volt circuit provides power at 8.8kW. Thus, fully charging the flywheel from full discharge would require a little more than 4 hours, and this power would be purchased at low overnight rates when utility demand is lowest (at least at present). This could all change, obviously, if charging of hybrid-electric and electric vehicles, and flywheels, becomes widely used. In any case, overnight rates should be lower than daytime rates, especially peak rates.

To utilize a flywheel generator for a home a reliable control system will be required. Much design effort is going into control systems at present (e.g., for hybrid electric vehicles and smart grids), and this application would benefit from these efforts, but it would be an extra cost for the residential customer. Such costs, in addition to the cost of the flywheel and its enclosure and related electrical costs, would have to be balanced against the savings from using cheaper electricity at night. An important counterbalance is the potential set of savings to the utilities of reduced peak demand and the savings from using their currently underutilized generating equipment more fully at night. This raises the possibility of a utility advancing the costs of a flywheel system to its customers, based on its long term savings, as was done with customer installation of ground source heat pumps that also reduced utility peak demand. The advance is then paid back to the utility as an additional charge on the customer’s bill that is reduced by the use of the flywheel.

These are just initial thoughts that I hope will stimulate lots of additional thoughts and reactions. I await your feedback.

(Note: this blog was re-published in the August-September 2013 issue of The Alternative Energy eMagazine, which can be found at http://altenergymag.com/emagazine.php)