Category: LEDs

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.

More on the Lighting Revolution

This blog post is stimulated by an OpEd piece in today’s (12 December 2014) Washington Post. I reproduce it here as published before I comment on what it says.

“One of the most boneheaded anti-government policies of the last decade is back”

By Stephen Stromberg

A vintage-style incandescent light bulb (C) is shown with an LED light bulb (L) and a compact florescent (CFL) light bulb on December 27, 2013 in Chicago, Illinois (note: this picture not reproduced in this blog post). These incandescent bulbs, which have been in use for more than 100 years, are being replaced by the more energy efficient compact florescent and LED light bulbs. (Photo Illustration by Scott Olson/Getty Images)
In the trillion-dollar budget deal Congressional leaders revealed Tuesday, Republicans didn’t press to defund the Environmental Protection Agency’s climate change rules. But they did uphold one of the most boneheaded anti-government riders of the last decade.

Some quick background: The United States wastes astounding amounts of electricity on light bulbs. The Energy Department figures that American homes spend about 10 percent of their electricity bills on lighting, and households that use old, Edison-era incandescents convert less than 10 percent of the electricity they buy for their bulbs into light. The rest uselessly dissipates as heat.

Though households quickly save money on energy bills when they buy more expensive bulbs that waste less power and last longer, Americans for years didn’t push the transition forward absent a government nudge. This left hefty national savings on the table, as well as a surprisingly large environmental dividend. The EPA calculates that every incandescent bulb switched for a more efficient compact fluorescent bulb saves about 84 pounds in carbon dioxide emissions every year. The Energy Department figures that a transition to super-efficient LED bulbs by 2027 would save about 44 large power plants’ worth of electricity (h/t Brad Plumer).

So Congress passed some simple light bulb efficiency standards in 2007. Lawmakers didn’t ban incandescent bulbs. Instead they demanded that bulbs produced in or imported into the U.S. use no more than a certain amount of electricity to produce a certain amount of light. If manufacturers could make incandescents less wasteful, they could produce the improved bulbs freely. One result has been a boom in the commercialization of new lighting technologies that could save Americans some $6 billion next year.

Another result was an upsurge in counterproductive ideological fuming from the right: In a different budget compromise passed earlier this year, Republicans added a rider prohibiting the Energy Department from enforcing the bulb standards. The rules are still technically on the books, and major manufacturers have switched over to producing better bulbs. But the government won’t be able to stop anyone from playing to people’s short-term bottom line by producing, importing or selling ancient Edison bulbs. It’s not clear whether that will happen on a large scale, in part because retailers have been selling leftover inventories of old-design incandescent bulbs over the course of this year. But those supplies will run out. Regardless, in the latest budget deal Republicans again tacitly encourage undercutting the efficiency rules, keeping the rider in place.

Among other overblown complaints, critics have argued that the light that new bulb designs put out doesn’t feel the same as that of the old incandescents. In fact, bulb manufacturers have made great strides in adapting bulbs to Americans’ tastes. Even if they hadn’t, avoiding a few drawbacks in otherwise functional bulbs clearly isn’t worth wasting $6 billion and creating tons of extra emissions every year. Any rational government would push this transition along. I’m still not sure what kind of government Republican lightbulb hawks want.”

This is a topic I’ve commented on before (see my earlier blog post entitled ‘Lighting: A Revolution in Progress’) but feel the need to comment on again as some members of Congress are still pushing a policy that acts against the U.S. national interest – i.e., the need to reduce energy unnecessarily wasted in producing light. About one fifth of U.S. generated electricity goes into lighting, a large fraction, much of which can be saved by switching to more efficient and increasingly less costly forms of lighting such as LEDs. In addition to reducing the need for power plants to provide this electricity, associated carbon emissions and consumer electricity costs can be reduced significantly. This transition is inevitable and is picking up speed as LED costs come down as large-scale manufacturing of LEDs takes place.

My point in revisiting this topic is to emphasize some of the important points in the OpEd piece that unfortunately still need emphasizing with some members of Congress and the public: the economic and environmental benefits of switching from traditional incandescent light bulbs to LEDS are abundantly clear and U.S. Government action to impose standards on light bulb performance is not a ban on incandescent bulbs as some people have misrepresented. As the Oped correctly states: “So Congress passed some simple light bulb efficiency standards in 2007. Lawmakers didn’t ban incandescent bulbs. Instead they demanded that bulbs produced in or imported into the U.S. use no more than a certain amount of electricity to produce a certain amount of light. If manufacturers could make incandescents less wasteful, they could produce the improved bulbs freely.” If legislators see this imposition of standards as objectionable, then they must also be opposed to the variety of energy efficiency performance standards other Congress’ have mandated since the 1970s on devices such as refrigerators, air conditioners, and hot water heaters. Let them speak up if that is their position and take their arguments to and their chances with the American public rather than sneaking undiscussed items into must-pass budget legislation.

I would also like to take this opportunity to restate, in a simple example, the clear energy and economic benefits of switching from incandescents to LEDs. In the world of no-brainers this stands at the top of the class. In my earlier blog post I did this calculation for a CFL (compact fluorescent light bulb) which is now losing out to LEDs. The LED example is even more compelling.

In this example I compare a 60 Watt incandescent bulb (Sylvania A19 Soft White Dimmable) with an LED replacement (CREE 60W Soft White A19 Dimmable LED). The former are available at Lowe’s for $4.49 for a package of 8, and the 11 Watt LED is available at Home Depot for $7.97. The Sylvania bulb is advertised to have a 2,000 hour life while the identically shaped LED bulb is advertised to have a lifetime of “22.8 years (Based on 3hrs/day)”.

For purposes of calculation let me round the numbers off to 55 cents per bulb for the incandescents and $8 per bulb for the LED. Electricity is assumed to cost 10 cents/kWh. The LED lifetime is (3hours/day)x(365days/year)x(22.8years)=24,966 hours. In this amount of time you would replace the 55 cent incandescent light bulb 12.5 times.

Thus, after 24,966 hours the cost of using the incandescent bulb would be (0.06kW)x(24,966hours)x($0.10/kWh) = $149.8 + (12.5bulbs)x(0.55cents/bulb) = $156.7 (Note: this does not take into account any costs associated with replacing the bulb at least 12 times). The cost of using the LED to provide an equivalent amount and quality of light would be (0.011kW)x(24,966hours)x($0.10/kWh) = $27.5 + (1bulb)x($8/bulb) = $35.5.

This simple comparison demonstrates why a switch from incandescents to LEDs is inevitable and is already underway as initially high LED costs come steadily down. Even at $8/LED bulb the economic comparison ($36 vs $157) is devastating to incandescents, even improved incandescents that have been developed in response to the new efficiency standards. The economic argument for consumers is only buttressed by the benefits to electric utilities that need fewer power plants to meet lighting needs, and by the associated environmental benefits. Given that lighting needs consume about 19% of global generated electricity the benefits of this lighting revolution in combatting global warming and climate change are obvious.

While there can be debatable policy differences on how to generate the electricity we need, there should be no argument about proceeding down the LED path. This really is a no-brainer that even ‘Republican lightbulb hawks’ should understand.

Zero Energy Buildings: They May Be Coming Sooner Than You Think

Buildings account for approximately 40 percent of the energy (electrical, thermal) used in the U.S. and Europe, and an increasing share of energy used in other parts of the world. Most of this energy today is fossil-fuel based. As a result, this energy use also accounts for a significant share of global emissions of carbon dioxide.

image
Source: U.S. Department of Energy, Buildings Energy Data Book

These simple facts make it imperative that buildings, along with transportation fleets and power generation, be primary targets of reduced global energy and fossil fuel demand. This blog post discusses one approach in buildings that is gaining increasing visibility and viability, the introduction of net zero energy buildings and the retrofit of existing buildings to approach net zero energy operation. A net zero energy building (NZEB or ZEB) is most often defined as a building that, over the course of a year, uses as much energy as is produced by renewable energy sources on the building site. This is the definition I will focus on. Other ZEB definitions take into account source energy losses in generation and transmission, emissions (aka zero carbon buildings), total cost (cost of purchased energy is offset by income from sales of electricity generated on-site to the grid), and off-site ZEB’s where the offsetting renewable energy is delivered to the building from off-site generating facilities. Details on these other definitions can be found in the 2006 NREL report CP-550-39833 entitled “Zero Energy Buildings: A Critical Look at the Definition”.

The keys to achieving net zero energy buildings are straight forward in principle: first focus on reducing the building’s energy demand through energy efficiency, and then focus on meeting this energy demand, on an annual basis, with onsite renewable energy – e.g., use of localized solar and wind energy generation. This allows for a wide range of approaches due to the many options now available for improved energy efficiency in buildings and the rapidly growing use of solar photovoltaics on building roofs, covered parking areas, and nearby open areas. Most ZEB’s use the electrical grid for energy storage, but some are grid-independent and use on-site battery or other storage (e.g., heat and coolth).

A primary example of what can be done to achieve ZEB status is NREL’s operational RSF (Research Support Facility) at its campus in Golden, Colorado, shown below.

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It incorporates demand reduction features that are widely applicable to many other new buildings, and some that make sense for residential buildings and retrofits as well (cost issues are discussed below). These include:
– optimal building orientation and office layout, to maximize heat capture from the sun in winter, solar PV generation throughout the year, and use of natural daylight when available
– high performance electrical lighting
– continuous insulation precast wall panels with thermal mass
– windows that can be opened for natural ventilation
– radiant heating and cooling
– outdoor air preheating, using waste heat recovery, transpired solar collectors, and crawl space thermal storage
– aggressive control of plug loads from appliances and other building equipment
– advanced data center efficiency measures
– roof top and parking lot PV arrays

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U.S. ZEB research is supported by DOE’s Building America Program, a joint effort with NREL, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, and several industry-based consortia – e.g., the National Institute of Building Sciences and the American Institute of Architects. Many other countries are exploring ZEB’s as well, including jointly through the International Energy Agency’s “Towards Net Zero Energy Solar Buildings” Implementing Agreement (Solar Heating and Cooling Program/Task 40). This IEA program has now documented and analyzed more than 300 net zero energy and energy-plus buildings worldwide (an energy-plus building generates more energy than it consumes).

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An interesting example of ZEB technology applied to a residential home is NREL’s Habitat for Humanity zero energy home (ZEH), a 1,280 square foot, 3-bedroom Denver area home built for low income occupants. NREL report TP-550-431888 details the design of the home and includes performance data from its first two years of operation (“The NREL/Habitat for Humanity Zero Energy Home: a Cold Climate Case Study for Affordable Zero Energy Homes”). The home exceeded its goal of zero net source energy and was a net energy producer for these two years (24% more in year one and 12% more in year two). The report concluded that “Efficient, affordable ZEH’s can be built with standard construction techniques and off-the-shelf equipment.”

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The legislative environment for ZEB’s is interesting as well. To quote from the Whole Building Design Guide of the National Institute of Building Sciences:
“Federal Net Zero Energy Building Goals
Executive Order 13514, signed in October 2009, requires all new Federal buildings that are entering the planning process in 2020 or thereafter be “designed to achieve zero-net-energy by 2030”. “In addition, the Executive Order requires at least 15% of existing buildings (over 5,000 gross square feet) meet the Guiding Principles for Federal Leadership in High Performance and Sustainable Buildings by 2015, with annual progress towards 100% conformance”.
Two milestones for NZEB have also been defined by the Department of Energy (DOE) for residential and commercial buildings. The priority is to create systems integration solutions that will enable:
Marketable Net Zero Energy Homes by the year 2020
Commercial Net Zero Energy Buildings at low incremental cost by the year 2025.
These objectives align with the Energy Independence and Security Act of 2007 (EISA), which calls for a 100% reduction in fossil-fuel energy use (relative to 2003 levels) for new Federal buildings and major renovations by 2030.”

A word about cost: ZEB’s cost more today to build than traditional office buildings and homes, but not much more (perhaps 20% for new construction). Of course, part of this extra cost is recovered via reduced energy bills. In the future, the zero energy building goal will become more practical as the costs of renewable energy technologies decrease (e.g., PV panel costs have decreased significantly in recent years) and the costs of traditional fossil fuels increase. The recent surge in availability of relatively low cost shale gas from fracking wells will slow this evolution but it will eventually occur. Additional research on cost-effective efficiency options is also required.

To sum up, the net zero energy building concept is receiving increasing global attention and should be a realistic, affordable option within a few decades, and perhaps sooner. ZEB’s offer many advantages, as listed by Wikipedia:
“- isolation for building owners from future energy price increases
– increased comfort due to more-uniform interior temperatures
– reduced total net monthly cost of living
– improved reliability – photovoltaic systems have 25-year warranties – seldom fail during weather problems
– extra cost is minimized for new construction compared to an afterthought retrofit
– higher resale value as potential owners demand more ZEBs than available supply
– the value of a ZEB building relative to similar conventional building should increase every time energy costs increase
– future legislative restrictions, and carbon emission taxes/penalties may force expensive retrofits to inefficient buildings”

ZEB’s also have their risk factors and disadvantages:

“- initial costs can be higher – effort required to understand, apply, and qualify for ZEB subsidies
– very few designers or builders today have the necessary skills or experience to build ZEBs
– possible declines in future utility company renewable energy costs may lessen the value of capital invested in energy efficiency
– new photovoltaic solar cells equipment technology price has been falling at roughly 17% per year – It will lessen the value of capital invested in a solar electric generating system. Current subsidies will be phased out as photovoltaic mass production lowers future price
– challenge to recover higher initial costs on resale of building – appraisers are uninformed – their models do not consider energy
– while the individual house may use an average of net zero energy over a year, it may demand energy at the time when peak demand for the grid occurs. In such a case, the capacity of the grid must still provide electricity to all loads. Therefore, a ZEB may not reduce the required power plant capacity.
– without an optimised thermal envelope the embodied energy, heating and cooling energy and resource usage is higher than needed. ZEB by definition do not mandate a minimum heating and cooling performance level thus allowing oversized renewable energy systems to fill the energy gap.
– solar energy capture using the house envelope only works in locations unobstructed from the South. The solar energy capture cannot be optimized in South (for northern hemisphere, or North for southern Hemisphere) facing shade or wooded surroundings.”

Finally, it is important to note that the energy consumption in an office building or home is not strictly a function of technology – it also reflects the behavior of the occupants. In one example two families on Martha’s Vineyard in Massachusetts lived in identical zero-energy-designed homes and one family used half as much electricity in a year as the other. In the latter case electricity for lighting and plug loads accounted for about half of total energy use. As energy consultant Andy Shapiro noted: “There are no zero-energy houses, only zero-energy families.”

Lighting: A Revolution In Progress

An energy revolution is underway before our very eyes – the replacement of traditional incandescent light bulbs with much more energy efficient and longer lasting light-emitting diodes (LEDs). It is a significant revolution because, according to NYSERDA, lighting accounts for 22% of electricity consumption in the U.S.. Other sources put this number at 19% on a global basis. It is estimated that LED use could cut the U.S. number in half by 2030.

At this point it may be fair to ask: What about CFLs (compact fluorescent lamps), which had been gaining market share for many years. A few words about lighting technology before we answer this question.

An incandescent light bulb, the most common type today in households and the least expensive to buy, produces visible light from a glowing filament wire (tungsten) heated to a high temperature (several thousand degrees) by an electric current passing through it. It was not invented by Thomas Edison, as is often stated (many earlier inventors had experimented with hot filament lamps), but he did invent the first commercially practical incandescent bulb. It was introduced into residential use more than 125 years ago. Its principal shortcoming is that more than 90% of the energy used by the traditional incandescent bulb escapes as heat and less than 10% goes into producing light. Filaments also burn out and are fragile, and a typical bulb lifetime is about 1,000 hours.

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Halogen lamps, also in common use today, are incandescent lamps with a bit of halogen gas (iodine or bromine) added to the bulb. The chemical reaction between the halogen and the tungsten wire allows the filament to operate at a higher temperature and increases the bulb’s efficiency and lifetime.

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A fluorescent lamp or fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses UV-stimulated fluorescence of a phosphor to produce visible light. It is more energy efficient than an incandescent lamp but does require a ballast to regulate the current through the lamp, increasing its initial cost.

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Compact fluorescent lamps (CFLs) fold a fluorescent lamp tube into the space of an incandescent bulb with a ballast in the base. They use 3-5 times less energy than incandescent bulbs of the same light output and have much longer lifetimes. They do contain a small amount of mercury, creating a disposal problem.

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Light-emitting diodes (LEDs) are monochromatic, solid-state semiconductor point light sources. First appearing as practical electronic components in 1962, early LEDs emitted low-intensity red light, but modern versions are available at visible, ultraviolet, and infrared wavelengths with very high brightness. Today they are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting and traffic signals. They are also used in the infrared remote control units of many commercial products including televisions, DVD players and other domestic appliances. Their high switching rates are useful in advanced communications technology.

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LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. However, LEDs powerful enough for room lighting are still relatively expensive (but costs are coming down) and require more precise current and heat management than compact fluorescent lamp sources of comparable output. Their advantages over CFLs are greater efficacy (i.e., more light output in lumens per watt), longer lifetimes, smaller size, directionality of the light produced, and very importantly they contain no mercury which has to be disposed of. These factors will limit CFLs’ time in the ‘limelight’ (I know, bad pun).

(Note: LEDs are based on inorganic (non-carbon-based) materials. OLEDs are organic (carbon-based) solid-state light emitters which are made in sheets that provide a diffuse-area light source. They are still in an early stage of development and several years away from broad commercial application. Interesting potential applications include TVs, computer and cell phone screens, wall coverings that allow changes in color, and automobile skins that allow you to change the color of your car.)

It is useful to compare these different lighting technologies, as white light emitters, in terms of their current efficiencies (efficacies), lifetimes, and color temperatures (measured in degrees Kelvin, as an indicator of the warmth or coolness of the light emitted). Efficacies for monochromatic LEDs are higher but are not listed here.

Technology Efficacy Lifetime Color Temperature
(lumens/watt) (hours) (K)
…………………………………………………….
Incandescent 12-18 750-1,500 2,400-2,900
CFL 60-70 6,000-10,000 2,700-6,500
Fluorescent tube 80-100+ 20,000 2,700-6,500
Halogen 16-29 2,000-4,000 2,850-3,200
White light LED 20-50. Up to 100,000 2,700-6,500

A quick calculation will help to demonstrate the cost effectiveness of lighting sources that may be more costly to buy but save energy and money over extended lifetimes (and don’t forget that not replacing bulbs as often also saves money by reducing labor costs). I will use CFLs as my example.

Assume we buy a 15 watt CFL bulb that today costs $6 and replaces a 65 watt incandescent bulb that costs $1. We further assume that the CFL will last 6,000 hours, the incandescent 1,500 hours (clearly a worst case for CFLs and a best case for incandescents), and that electricity costs 10 cents per kilowatt-hour. Over 6,000 hours the CFL will consume (0.015 kW)x(6,000h)=90 kWh for a total cost (purchase + energy use) of $15. The incancandescent will have been replaced four times in 6,000 hours and consumed (0.065kW)x(6,000h)=390 kWh for a total cost of $43. You save lots of money ($43-$15=$28) despite the higher initial cost for the CFL, and this is per bulb. In addition to this reduced cost the reduced energy consumption will be reflected in fewer carbon emissions from power plants supplying the needed electricity.

Finally, a word about the claim that the U.S. Congress has outlawed use of the incandescent bulb. This is not true, although other countries have done so. What the U.S. Congress has done is pass the Energy Independence and Security Act of 2007, which set performance standards for all general service incandescent lamps producing 310-2,600 lumens of light. The efficiency standard will start with 100-watt bulbs and end with 40-watt bulbs. Light bulbs outside of this wattage range are not covered, along with several classes of specialty bulbs (e.g., stage lighting). Thus, if bulb manufacturers can develop an incandescent bulb that meets the specified performance standard it can be marketed and sold in the U.S. Some are even beginning to appear. This is the same approach that is taken with respect to reducing the electricity consumption of many other household appliances such as refrigerators and dish washers.