Month: March 2014

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.”

Oil Spills and Our Inability to Clean Them Up Properly

While preparing my latest blog (on zero energy buildings – to be posted shortly) I read the attached piece on the Washington Post’s OpEd page for March 29, 2014: “We Still can’t clean oil spills”. It was authored by Frances Beinecke, president of the Natural Resources Defense Council, and because I think it is a very important article I am reprinting it here to facilitate its distribution. BP, Exxon and other oil companies can advertise all they want about their commitment to safety, but advertising doesn’t substitute for investments in safety research and deployment of safety equipment and practices in an industry that will inevitably experience accidents. Reduced dependence on oil is the long-term strategy that we also need to pursue aggressively.

“25 years after Exxon Valdez, we still haven’t learned to limit oil drilling

By Frances Beinecke, Published online on March 28

Frances Beinecke is president of the Natural Resources Defense Council. She was a member of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling.

Twenty-five years ago this month, the Exxon Valdez struck a reef in Alaska’s Prince William Sound and dumped 11 million gallons of crude oil into the water. The public was shocked by photos of oil-soaked otters and reports that coastal residents had lost their livelihoods. The cleanup effort was so vast it required 11,000 people, some of whom scooped up oil with buckets. People were outraged.

Two decades later, the Macondo well beneath the Deepwater Horizon blew out, killing 11 and sending 170 million gallons of oil into the Gulf of Mexico. I served on the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, and I saw firsthand the oil-drenched beaches and the anxiety of coastal residents. It was hauntingly familiar. Many lessons from the Exxon Valdez spill had not been applied, and the country was once again struggling with an industry ill-prepared to respond.

Flash forward four years, and oil spills continue to endanger our waters. A week ago , a barge and ship collided and spilled about 168,000 gallons of thick, viscous oil into Galveston Bay near a vibrant bird sanctuary.

An even greater potential disaster looms. Shell Oil plans to drill in Alaska’s next frontier — the Arctic Ocean, a region even more pristine and remote than Prince William Sound. The company’s initial attempts were plagued by failed emergency equipment, a 32-mile-long ice floe and a grounded drill rig. If this last unspoiled ocean isn’t put off-limits in a hurry, we could witness a spill of far greater proportions.

Our country can learn from experience. Preserving marine riches for generations to come makes more sense than trying to bring them back from the brink of the latest disaster.

Here is what we know and must act on today:

The oil industry is still using the same ineffective technology to clean up oil in water as it was 25 years ago. Exxon was woefully ill-equipped for cleaning up Prince William Sound, and the industry vowed to invest in better technologies. Yet when the Deepwater Horizon spill occurred, the industry showed up with the same tools: containment booms and dispersants. Companies spent billions of dollars to advance drilling technology but only a fraction on cleanup research. They had nothing new to offer. And those booms managed to pick up just 3 percent of the oil spilled in the Gulf.

Since the BP spill, companies have increased the number of available well caps, ships and booms, but they have had few breakthroughs in cleanup ability. That is alarming for the Arctic, since booms have not proved capable of cleaning up oil in an Arctic environment shrouded most of the year in ice, fog and gales.

This is particularly important since we now know that oil lingers for decades. In 2003, researchers found that more than 21,000 gallons of oil from the Exxon Valdez tanker remained in Prince William Sound, and some is still present. A recent study concluded that the region’s harlequin duck and sea otter populations have rebounded — but that took 24 years. Pacific herring have reached only 15 percent of pre-spill levels, gutting what was once a $12 million fishery in Prince William Sound. And while one pod of orca whales hit hard by the spill is recovering slowly, the other is headed for demise.

In Louisiana, oil from the Deepwater Horizon spill continues to wash ashore, and researchers are just beginning to understand its effects on the food chain. It’s clear that oil spills cannot be wiped away in a matter of months or a few years, and they can imperil wildlife for generations. Our remaining polar bears and some of our last beluga whales must not be exposed to the same dangers in the Arctic Ocean.

Congress has failed to strengthen safeguards for offshore drilling since the Gulf of Mexico disaster. Just one year after the Exxon Valdez spill, Congress passed the Oil Pollution Act and generated important improvements in tanker safety. Yet in the aftermath of the larger spill in the Gulf, Congress hasn’t passed a single law to rein in an industry known for reckless operations and resistance to oversight.

It is long past time for Americans to hear what oil disasters keep telling us: Our safeguards and cleanup equipment aren’t sufficient, and our oceans and coasts remain vulnerable to long-term damage.

The oil industry and Congress must fill the holes in our safety net and recognize that some places should be off-limits to drilling. The fragile and beautiful Arctic Ocean is one of them. I do not want to mark the 25th anniversary of the Deepwater Horizon spill by reflecting on an oil disaster in the Arctic. Let us learn from history and create a safer, clean energy future.”

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Exxon-Valdez Alaska oil spill

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BP Gulf of Mexico oil spill

Electrochromic Windows: We Need to Get the Cost Down

A technology that has fascinated me since I first saw it demonstrated nearly forty years ago is the electrochromic window. It is part of the family of smart glass technologies that control the amount of light and heat that the glass transmits. This control can be activated by temperature (thermochromic), by light (photochromic), or voltage (electrochromic). This blog post will focus on the latter, which offers significant potential for reducing the energy consumed in buildings. Electrochromic windows have other useful applications as well.

How do electrochromic windows work?

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When a voltage is applied between the transparent electrical conductors (usually less than 5 volts) an electric field is set up in the window material. This field moves ions reversibly through the ion storage film through the electrolyte and into the electrochromic film. Different ions (typically lithium or hydrogen) produce different colorations, and the window can be switched between a clear, highly transparent state and a transparent blue-gray tinted state with no degradation in view (similar to that achieved in photochromic sunglasses) by reversing voltage polarities. Critical aspects of electrochromic windows include material and manufacturing costs, installation costs, electricity costs, and durability, as well as functional features such as degree of transparency, possibilities for dimming, and speed of transmission control (complete switching can take several minutes). Many different electrochromic window options at different price points for buildings are now available, and active R&D efforts are underway. One recent advance is the development of reflective, rather than absorptive, windows which switch between transparent and mirror-like.

Electrochromic windows are an attractive energy efficiency measure because they can block heat (infrared radiation) in the summer, reducing air conditioning loads, and allow infrared wavelengths to pass into buildings in the winter and reduce heating loads (windows account for about 30% of building energy load). This also reduces utility peak load demands. Tunable electrochromic windows also serve to reduce lighting loads when adequate natural light is available, reduce glare, provide privacy without the need for blinds and curtains, and reduce fabric and art fading by blocking ultraviolet radiation.

Important applications, in addition to reducing energy demand and increasing human comfort, include use in automobile windows, sunroofs and rear view mirrors, in aircraft (e.g., the Boeing 787 Dreamliner uses electrochromic windows in place of pull down window shades), and as internal partitions in buildings with the ability to switch screens and doors from clear to private.

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Given that electrochromic (EC) windows have been under development for many decades, their obvious ability to block or transmit wavelengths of light as needed, and their many applications, why hasn’t greater use of such windows become a standard part of building construction. The simple answer is cost. NREL looked at this issue in its December 2009 report entitled ‘Preliminary Assessment of the Energy-Saving Potential of Electrochromic Windows in Residential Buildings’ and compared the cost of low-e argon-filled windows with that of EC windows and concluded that “..EC windows would have to reach a price point of approximately $20/square foot before they would be competitive..” At that time EC windows were in the range $50-100/square foot, with commercial buildings on the lower end and residential applications on the higher end. Another approach bring taken by a few EC window companies is to add an EC film to existing windows, which reduces costs considerably.

How much energy can EC windows save? The NREL study, using a model to evaluate the performance of EC windows in a single-family traditional new home in Atlanta, predicted that whole-house energy demand could be reduced by 9.1% and whole-house electricity demand by 13.5%.

Looking globally, the U.S. and China have joined in a $150 million consortium called the U.S. China Clean Energy Research Center aimed at facilitating “joint research and development on clean energy technology. The consortium estimates that in the next 20 years China will build more square footage of floor space than the current total in the United States. The goal is to make those buildings as energy efficient as possible.”

Several new factories have been or are being built to produce EC windows or EC films and reduce costs significantly through economies of large-scale production. My intuition says this will happen soon, and will serve as an important step toward zero-energy buildings – i.e., buildings that use no more energy in a year than they produce through PV generation. A future blog will discuss zero-energy buildings in more detail.

Animal Wastes: An Energy Resource That Is Win-Win

I first became aware of the animal waste issue in 1995 when a lagoon of liquid pig wastes in Iowa overflowed its banks and contaminated a nearby waterway. It made the national news, including the Washington Post, and resulted in one of my DOE colleagues asking me if we had a program to generate fuels/energy from such wastes. This was a logical question as I then headed DOE’s renewable electricity programs and biomass issues were under my purview. I answered honestly, no, but immediately headed to the offices of my biomass program and directed that such a program be started. I designated one of the senior biomass staff to head it up, it started the next day, and the new program head, a Ph.D, was unofficially given the title “Dr. Poop”.

Not having such a program earlier was clearly an oversight on my part, and I began to educate myself on the realities of animal wastes and their possibilities for productive application. One step was tracking down people in the DOE national laboratory system that knew about such things, and I found an expert at Oak Ridge. He directed me to useful information, of which there was quite a bit, and helped me organize an all-day meeting at the University of Tennessee with animal waste experts that explored these issues in detail. It was illuminating to say the least, especially for this boy from the Bronx who didn’t see his first bull until he was 16 and his first pig until he was in graduate school. I’ve never been the same since.

A few facts and numbers will put the issue in context. The U.S. produces lots of livestock (cows, chickens, turkeys, etc.) and therefore lots of animal wastes. Until recently the U.S. was the leading global meat producer but is now #2 behind China (42 million metric tons/MMT vs. 83 MMT), with Brazil coming in third at 25 MMT. EPA, which plays an important role in animal waste management in the U.S., estimates that this waste is produced on 1.3 million farms across the nation. The numbers of animals raised each year in the U.S. is staggering – more than 9 billion chickens, 250 million turkeys, 100 million beef and dairy cattle, 65 million pigs, and other animals (sheep, goats, ..) that are raised as part of our food economy. The net result of all this is about one billion annual tons of animal wastes – about ten times the amount of municipal sewage – that have to be dealt with in a way that does not jeopardize human, fish, or ecosystem health.

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Why are animal wastes a threat? Agriculture, including livestock, is a major source of nitrates that pollute water supplies. Animal wastes also contain disease-causing pathogens such as E coli, Salmonella, and Cryptosporidium that can be many times more concentrated than in human waste. “More than 40 diseases can be transferred to humans through manure.” Antibiotics added to animal feed to project against infection and speed up llivestock growth (about 30 million pounds annually, or 80% of antibiotic use in the U.S.) gets into human foods and contributes to the evolution of anti-biotic resistant bacteria. In addition, wastes at pig farms emit hydrogen sulfide, a corrosive gas that if inhaled at high concentrations can lead to brain damage and death.

Can’t we just contain this stuff so it doesn’t get into our water supplies? The facts are that some waste lagoons are as big as several football fields and are prone to leaks and spills.

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To quote the Natural Resources Defense Council:
“In 1995 an eight-acre hog-waste lagoon in North Carolina iburst, spilling 25 million gallons of manure into the New River. The spill killed about 10 million fish and closed 364,000 acres of coastal wetlands to shellfishing.

In 2011, an Illinois hog farm spilled 200,000 gallons of manure into a creek, killing over 110,000 fish.

In 2012, a California dairy left over 50 manure covered cow carcasses rotting around its property and polluting nearby waters.

When Hurricane Floyd hit North Carolina in 1999, at least five manure lagoons burst and approximately 47 lagoons were completely flooded.

Runoff of chicken and hog waste from factory farms in Maryland and North Carolina is believed to have contributed to outbreaks of Pfiesteria piscicida, killing millions of fish and causing skin irritation, short-term memory loss and other cognitive problems in local people.

Nutrients in animal waste cause algal blooms, which use up oxygen in the water, contributing to a “dead zone” in the Gulf of Mexico where there’s not enough oxygen to support aquatic life. The dead zone fluctuates in size each year, extending a record 8,500 square miles during the summer of 2002 and stretching over 7,700 square miles during the summer of 2010.

Ammonia, a toxic form of nitrogen released in gas form during waste disposal, can be carried more than 300 miles through the air before being dumped back onto the ground or into the water, where it causes algal blooms and fish kills.”

Complicating all this is the reality of ‘intensification’, the fact that “..smaller family farms have been replaced by corporate operations hounding thousands of animals in assembly-line conditions.” For example, the number of pig farms in the U.S. in 2011 was one tenth the number in 1980 but the number of pigs sold was about the same. Ten companies today produce more than 90% of the nation’s poultry and 70% of U.S. beef cattle come from farms with at least 5,000 head of cattle.

This concentration of livestock growing in factory farms, called concentrated animal feeding operations (CAFOs) is driven by economic imperatives. It leads to a buildup of animal wastes in small land areas, which if properly stored and used, can be a valuable resource. If not properly managed the waste produced by CAFOs can pollute the environment, especially water sources. Waste is often pumped into open-air lagoons from which liquid manure is sprayed onto fields as fertilizer. The amount of waste applied often exceeds what the crops can absorb, leaving the rest to escape into the air or as runoff into surface waters.

There are many productive uses of manure, including fuel and energy production. These include recovery of undigested anti-biotics, recovery of solid materials for use in building materials, and production of dry plant and crop fertilizer that is the byproduct of biodigestion. It is this latter activity that offers a ubiquitous and large energy resource.

As reported by the Agriculture Extension Division of Colorado State University: “The demand for clean energy, coupled with concern for management of livestock wastes, has revived an interest in generating methane from livestock manures. The most widely accepted technology currently available for converting organic wastes present in livestock manure is anaerobic digestion (AD). AD is a biological process by which microorganisms convert organic material into biogas, containing methane and carbon dioxide. Biogas produced by this process can be utilized to generate electricity or can be cleaned up and supplied to natural gas lines. Collection and utilization of methane generated from livestock manure offers the potential to reduce global emissions of methane (a greenhouse gas), reduce CO2 released from fossil fuels, diminish odor from agricultural facilities, and improve water quality. In many cases, anaerobic digestion either decreases on-farm energy costs or increases revenues from energy resale.” An interesting number is that, on average, “..a single dairy cow produces approximately 120 pounds of wet manure per day” which has an energy value of about 14,000 BTU. Thus, “It would take manure from approximately 50 cows to produce enough biogas for heating a typical home.”

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Proper management and use of animal wastes is clearly a ‘win-win’ if we can prevent water and air pollution and tap into a potentially large energy resource. For example, China is actively pursuing biodigestion of human and animal wastes, particularly in rural areas that lack grid connections, for producing biogas for lighting and cooking. The International Energy Agency’s CADDETT Reneable Energy Program (http://www.caddett-re.org) “..gathers information on full-scale commercial projects which are operating in the member countries..”. Its Renewable Energy Register, a database of demonstrated renewable energy projects, contains many biodigestion entities – e.g., ‘Poultry Litter as a Fuel for Electricity Production’, ‘Electricity and Heat from the Aanaerobic Digestion of Farm Wastes’, and ‘Centralized Manure Digestion Plant’. Information is readily available; what is now needed is widespread implementation.