Category: Wind energy

Report of an Interview – Republished From the ECOreport

The attached piece, written by Roy Hales and first published in the ECOreport on February 3, 2015 (www.theECOreport.com) was based on a voice interview he held with me on January 31st. It came about when Roy asked me if I would be willing to comment on the recent report issued by DOE’s Energy Information Administration (EIA) that presented figures on new electrical generating capacity installed in the U.S. in 2014. I agreed to do so and the interview (to be radio broadcast) and the attached article are the results. The article is republished with Roy’s permission and speaks for itself.
(Note: the photos published with the original piece did not reproduce in this republished copy and can be found at the web site referenced above.)

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RENEWABLES
THE GROWTH OF US RENEWABLES DURING 2014 AS A VINDICATION
FEBRUARY 3, 2015 ROY L HALES
By Roy L Hales

It has been 37 years since Dr Allan Hoffman gave President Jimmy Carter the plan that could have started America’s renewable revolution. The idea was shelved after Reagan was elected. Hoffman waited, as administration after administration ignored the potential, until Barack Obama was elected. The retired senior Department of Energy executive views the growth of US renewables during 2014 as a vindication of what he and his colleagues saw decades ago.

More Than Half Of The New Capacity

(Note: Clean Technica estimates that 54.8% of the installations made in December came from these two sectors and 53.3% of the installations for the year.)

“If the Clean Technica chart (which includes an estimate for non-utility solar) is accurate, more than half of the new capacity added last year is from renewables. This is very significant. I pinch myself when I see these numbers and I am very grateful to see the transition move to the extent it has,” said Hoffman.

Though natural gas was still the leading single energy source, in terms of installations during 2014, its 7.5 GW of added capacity is overshadowed by close to 10 GW from the renewable sector.

Natural Gas Will Be With Us For Decades

Photo Credit: US Electricity Capacity Added in 2014 by Clean Techncia
“There is no doubt that natural gas will be with us for decades, but I don’t see it as a long term option,” said Hoffman. “Right now it is exciting. We will probably use more natural gas in transportation. It is perfectly suited for that, if you build the right kind of car, but I think electrification is the answer for most forms of transportation in the future.”

He used the automotive sector to illustrate what is happening with fossil fuels. The trend is to electrification, but EVs are not yet ready to take over. Around 70% of car trips, in the US, are less than 40 miles. EVs can supply this, but there is still a need for a gas or diesel back-up on longer trips.

“There are a lot of vested interests protecting fossil fuel use. You are going to see a determined battle from the petroleum industry, who want to continue their role in transportation. That doesn’t change overnight. Cars are on the road for an average of 10 to 12 years in the United States. They need petroleum, so that’s going to be with us for a while,” said Hoffman. “But I don’t think the fossil fuel industry can win this battle over the long term and the smart companies will be switching over eventually.”

He added, “We will still have fossil fuels in 2050, but it will be a diminishing fraction. We will move increasingly to electrification. Our children and grandchildren will eventually drive electric cars.”

Alternatives, like biofuels and biojet diesel, will eventually replace fossil fuels in sectors like aviation. The US Airforce is already moving in that direction. Even the US Navy, which uses bunker fuel to power many of its ships, is switching over.

The Real Future Of This Sector Is Offshore

The 4 GW of wind capacity added in 2014 is impressive, but Hoffman believes the real future of this sector is offshore.

“I consider offshore wind to be the most important and exciting emerging renewable technology. When you go offshore, the winds are stronger and more steady. That’s really critical because more steady winds produce a higher capacity factor. A larger fraction of the potential is realized in generating energy, which is really the ultimate test. The other thing is that with higher speeds, the economics become much better. The energy extracted from the wind goes as the third power of the wind speed. So if you double the wind speed, you get eight times the power out of that machine,” said Hoffman.

Developers can also build larger turbines than on land. There are a lot of logistics involved, but 6 to 7 MW turbines are presently common offshore. Hoffman has seen plans for 10MW to 15MW and even a 20 MW turbine.

“Of course there will be hurricanes and things like that and these machines have to hold up under those conditions, but I have confidence we can do that.”

Photo Credit: Total US Capacity at the end of 2014 by Clean Techncia
“The resource available in offshore wind is very, very large. Look at the United States. It has four coastal regions: The East Coast; The West Coast; The Gulf Coast; and the Great Lakes Coast. There is a lot of wind available.”

There is a potential for close to 4,000 GW of capacity, according to the National Renewable Energy Laboratory’s (2010) report “Large-Scale Offshore Wind Power In The United States.” This figure needs to be reduced, by subtracting areas (like shipping lanes) where you cannot put wind turbines, but the potential is still HUGE.

“To put this number in perspective, the United States’ present potential for generating electricity is just over 1,000 GW,” said Hoffman. “So even if only a fraction of offshore potential is realized, we have a major source of energy coming online in the future.”

Though the US has been slow to adopt offshore wind, Hofffman expects that to change in the next few years. It will start on the East Coast, where the winds are strong and a large part of the population lives.

New Solar Capacity

Photo Credit: Powerfilm Solar Panel by Stephan Ridgway via Flickr (CC By SA, 2.0 Liicense)
The 5.2 GW of new solar capacity added in 2014 is also impressive, but just a beginning. The potential for growth in this sector is enormous.

“Solar may be the fastest growing energy source in the world today. Look at what’s happening in Germany. There are days when more than half the electricity comes from solar and Germany is not a particularly sunny country, said Hoffman. “So I can see that happening in the United States. States like Nevada, Arizona have an incredible solar input.”

Resistance From Utilities

“There has been a lot of resistance from utilities. They have resisted net metering and other simplified connections to the grid because they see it as diminishing the importance of their business model. They make a lot of money selling energy at peak hours, when electricity is more expensive. If solar provides energy during those peak hours, their business model is upset. They are going to resist it for as long as they can because change is hard for people to accept.”

This battle is already over in Germany, where the four major utilities have now switched over to become providers of solar energy. They lease solar systems, maintain them and are now offering energy storage for homes.

Hoffman perceives the utility model of a centralized grid as a relic from the past. There will be more of a variety of systems in the future. Some people will utilize battery storage to be independent of the grid, there will be more local microgrids, regional grids and possibly even a global multinational grid.

“I have no question that this is happening. It’s happening as we speak. It will unfold over the next decades, but I think it is inevitable,” said Hoffman.

Though he believes both nuclear energy and natural gas will continue for several decades, Hoffman predicts their importance will diminish. Environmental pressures and economic realities are pushing the US into renewables.

“Eventually Congress will have to move in this direction, even Republicans can get the message,” he said. “What’s going to happen is that people are going to be talking to their members of congress. The business community has a major impact on Congress and they are going to see it is in their interest to move ahead with a clean energy system.”

US Needs To Adopt An Energy Plan

Photo Credit: Library of Congress by Juan Llanos via Flickr (CC BY SA, 2.0 License)
The US needs to adopt an energy plan, so that people have certainty about the future. Businesses need it, so they can formulate their own strategies.

“Climate Change is real and it has adverse effects, but they are long term effects,” said Hoffman. “Someone has to do the long term thinking to protect this generation as well as future generations from having to deal with it under less desirable conditions.”

Despite the resistance in Congress, Hoffman believes a carbon tax is inevitable. “Putting a price on emissions” is probably the best was to reduce them. The revenues can be used to reduce other taxes, like income tax, or redistributed to low income persons who are adversely affected by increased energy costs due to a carbon tax.

“I think there are a lot of tradeoffs on a carbon tax that would not only address carbon emissions, but that could also provide revenues that can be applied to other aspects of our economy,” said Hoffman.

“I see the early stages of what I consider an inevitable transition away from traditional energy sources, largely fossil fuel sources but also including nuclear to some extent, to an increasing reliance on renewable energy in the form of wind, solar, geothermal, biomass and eventually ocean energy as well.”

“I have been saying this was inevitable for many years, but for a long time it was hard to get people to accept that. I think we’re seeing it happen. When you look at the numbers, both from the Energy Information Administration (EIA) of the Department of Energy and the Federal Energy Regularity Commission (FERC) you can see that the transition is beginning to take place. The new capacity that is coming online is largely renewables.”

(Top Photo Credit: Photo Credit: Lillgrund Wind Farm, Near Copenhagen by Håkan Dahlström via Flickr (CC By SA, 2.0 License)

A Conversation With S. David Freeman

Had a most interesting discussion at lunch today (3 September 2014) with Dave, whose name is well known to older generations of energy policy types but less well known to many younger folks. He and I first met when we both joined the staff of the U.S. Senate Commerce Committee on October 1, 1974. Dave joined as a full-time energy staffer just after leading a major review of national energy policy sponsored by the Ford Foundation (‘A Time to Choose: America’s Energy Future’), and me as a Congressional Fellow/Staff Scientist. Dave is now 88 years old (I’m a relatively young 77) and in my opinion is as sharp, feisty and opinionated as he was when I first met him forty years ago. In the interim he has held a series of high level jobs (Chairman/TVA, General Manager/Sacramento Municipal Utility District, General Manager/New York Power Authority, General Manager/Los Angeles Department of Water and Power) and is still active in trying to close down California’s aging and poorly located nuclear power plants. We had not seen each other in a number of years and today’s lunch was a chance to catch up a bit.

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We met at noon at his apartment building in DC, and after walking to a nearby barbeque restaurant we got down to filling in the years. We reflected on the work we both did in the 1970’s on energy issues during Senator Warren Magnuson’s tenure as Chairman of the Commerce Committee, and on the many talented people we worked with at that time. We then discussed Dave’s time in Knoxville where he pushed hard to introduce conservation and solar energy into TVA’s energy portfolio and resisted the pressures to add more nuclear power plants. These priorities characterized his subsequent roles at SMUD, NYPA, and LADWP, and remain his priorities today. He was an early voice for clean energy in the U.S., and was appointed by President Johnson in 1967 as “..the first person with an energy responsibility in the federal government.” He has also been termed an “‘eco-pioneer’ for his environmentally-oriented leadership of SMUD.”

Our lunchtime discussion, after appropriate reminiscences, devolved into a discussion of energy policy under President Obama. Dave appreciates that Obama has an understanding of the importance of energy efficiency and renewble energy to our future energy system, but feels strongly that Obama is indecisive and has failed to put action behind his words. In fact, Dave called him “gutless” for failing to provide needed leadership on reducing our use of fossil fuels and making an all-out push on renewables. Dave’s feeling is that Obama is too cautious by nature (he quoted the opinion of an Illinois politician who had worked with Obama) and unwilling to stick his neck out, when what this country needs is a Preident who does just that. Notwithstanding the argument that the President is having a hard time getting any legislation through the Congress, and may have even more trouble after the November elections, Dave’s argument is that we have a critical need to reduce carbon emissions and that we have to start somewhere, even if it takes 10 years to get a meaningful program implemented. It is a powerful argument, as nothing gets done if one doesn’t try.

Dave gave me a lot to think about, as I’ve been a strong supporter of the President and his energy policies, but admit to being concerned about the President’s limited public explanations of his policies, whether energy or foreign policy. He may understand the issues, and Dave and I agree that he does, but is the President being too cautious by far? As a result, is he passing up an opportunity to lead the country in a needed direction at a critical time? As the leader of the nation is it encumbent upon him to propose legislation that limits our use of fossil fuels and puts us more aggressively on the path to a renewable future, even if the likelihood of passage is low to nonexistent in the near future? Upon leaving Dave after lunch I decided to write about our conversation and raise the question that Dave poses. This is the result.

My thoughts upon reflection are the following: despite the obvious resistance that Obama faces from Republicans on anything he proposes, and the need to keep a Democratic Senate if at all possible (so that his last two years in office will not be even more difficult than his first six years), should the President think big and propose what he knows the country needs as opposed to what is politically feasible? My heart says yes, and the side of me that claims to be practical, after many years in Washington, DC, tries hard to understand Obama’s strategy and support it. But Dave may be right – we may have an intellectual President whose nature just won’t allow him to stick his neck out. As I said to Dave, the test for me will be after the November elections, when Obama will have no Democratic candidates to protect and nothing to lose by proposing farseeing energy and environmental legislation. He will not succeed in getting it passed by the most dysfunctional Congress I’ve seen in forty years, but as Dave says, we have to start somewhere.

As those who read my blog will recall, I’ve taken issue with the Clinton-Gore Administration for not doing more on clean energy when they had the chance in the 1990’s. Dave’s point about Obama is similar – we need leadership that looks down the road despite today’s political realities. My final verdict on the Obama Administration’s achievements on energy policy will depend on what comes out of the White House after November. I hope that the President has it in him to do what Dave and I both agree the country needs, but at this point I still have confidence in President Obama. Dave does not.

This is a lot to think about, and I will continue to cogitate on Dave’s perspectives. Hopefully, others will join this discussion via comments on this blog post.

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.

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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.

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.

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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.”