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China Working Toward Green Energy Solutions
The International Energy Agency recently said China has become the world's biggest energy consumer - surpassing the United States.
by Peter Simpson, Voice of America
Beijing, China -- The huge turbines at the Guanting Wind Farm are popular backdrops for photos of newly married couples who find the 60-meter-tall structures a symbol of modernity; an endearing addition to the distant mountains, corn fields and lake a few dozen kilometers outside bustling Beijing.
The hum of the spinning blades is the sound of China going green as it seeks to address the growing energy demands of its rapidly modernizing consumer society and fast-paced industrialization.
China was angered when the International Energy Agency recently named the country the world's biggest energy user and emitter of carbon dioxide.
A leading researcher at China's National Development and Reform Commission Energy Research Institute, Hu Xiulian says the IEA's statistics are unreliable and biased.
Hu says Chinese statistics prove China is not yet the world's largest energy user. She cites oil consumption figures as an example that contradict the IEA's findings.
But International Energy Agency Chief Economist, Fatih Birol, denies bias in the agency's calculations.
"We included the same data for all countries; we follow the U.N. agreed conventions and definitions," Birol explained. "This is data under primary energy sources of all the countries. We have no problem whatsoever with any country arguing about the numbers."
There is no denying hundreds of millions of Chinese are buying homes, refrigerators, TV sets, vehicles and other energy-hungry trappings of a consumer society. It is routinely reported China relies heavily on cheap and widely available coal, the main resource that creates the rising carbon dioxide levels blamed for global warming and other environmental damage.
But only one third of China's vast population is enjoying a modern lifestyle; hundreds of millions more consumers will be demanding energy in the years ahead.
China is building hundreds of coal-powered energy plants each year. Coal fuels 70 percent of China's energy consumption, making the country the largest consumer and producer of coal in the world.
Beijing has refused to agree to cap its overall growth in its consumption of fossil fuels or reduce its emissions of carbon dioxide and other greenhouse gases.
That frustrated U.S. President Barack Obama and other world leaders' efforts to forge an international climate agreement at a U.N. summit in Copenhagen last December.
But the world's most populous nation is also a leader in renewable energies.
Global research company REN 21 - a network of governments, non-government organizations, and industry associations - reports China's total wind power doubled for the fifth year in a row in 2008, ending that year producing 12 gigawatts and passing its 2010 development target of 10 gigawatts two years early. Solar and water power generation are also being rapidly expanded.
The IEA's Birol agrees that when it comes to going green, China is another world leader.
"I am following the energy policies of almost all the big countries of the world, and there is no other government which is as dynamic as the Chinese government in putting energy policies in place," Birol said.
Guanting Wind Farm security supervisor Zong Minqiang says all the power produced on the farm makes up one-tenth of Beijing's electricity needs.
Zong says the farm was constructed to help clean up Beijing for the 2008 Olympics. He says the farm helps ease Beijing's reliance on dirty energy that creates the capital's notorious smog.
In the wake of the global financial crisis, the Chinese government earmarked 14.5 percent of a $586-billion stimulus package to energy saving and green investments.
China has also attracted record investments from overseas companies in the past two years.
Yet traveling back to smog-bound Beijing, past industrial factories, high-rise apartment blocks under construction, shopping malls and the ever growing number of cars, the future once more looks uncertain.
How, one asks, will the government satisfy the energy demands resulting from the rising expectations of its 1.3 billion, consumer-hungry people? A small part of the answer is already blowing in the wind. But burning questions remain.
Reprinted from Voice of America, a multimedia international broadcasting service funded by the U.S. government through the Broadcasting Board of Governors.
A Textbook Example: Why American Schools Must Go Green
Schools across the country – including many in California and Colorado – are utilizing their rooftops and PPAs to go green in an affordable and socially responsible way.
by Michael Laine, MP2 Capital and Clint Montgomery, Superintendent, Northwestern Regional School District No. 7
Published: September 8, 2010
Schools are a black hole for energy consumption. The buildings, which often serve as the hub of communities, are open from early morning to late at night. With air conditioning or heating systems that run continually, it is not unusual for a single building to use hundreds of thousands of gallons of fossil fuel each year. While this energy consumption is a major concern to students, teachers, administrators and the community – who all wish to lessen dependence on fossil fuels – school systems are moving at a glacial pace when it comes to making environmentally conscious decision regarding what technologies should power their facilities.
One of the primary reasons why school systems get cold feet at the idea of going green is the perceived cost of deploying renewable energy systems. School budgets across the United States are incredibly tight, a situation that is exacerbated by the nation’s current economic condition. As a result, school boards are faced with having to lay off teachers and cut core programs just to remain financially viable. Now is not the time, most seem to believe, to be introducing major infrastructure projects such as solar-or wind-power systems that have large price tags attached.
These perceptions, however, are far from reality. Schools can go green by deploying rooftop solar systems or tapping into wind energy projects by using a model that requires little to no upfront costs and can result in annual savings related to powering a facility. More importantly, though, these green projects can become a showpiece for the community to see how to successfully implement a renewable energy system.
For instance, they can provide value environmental education opportunities for students. In addition, they can serve as an example to other public facilities, private buildings or even homeowners of how to effectively invest in green technology. And finally, they can serve as engines of job creation and innovation not only in their city or county, but throughout their state and across the United States.
Leveraging a Public/Private Partnership – One Successful Partnership
When faced with the prospect of electricity costs rising 4-8% annually, the Northwestern Regional School District No. 7 in Winsted, Conn., began investigating what it would take to put a solar array on the roof of its 250,000 square foot high school building. While it could technically be done, the question of how to finance such a project loomed large. The school board considered three different ways to fund it:
* Outright Purchase – The school system could pay for building and maintaining its own solar infrastructure. This model was rejected because it required bonds, which were impossible to secure at the time.
* Lease/Purchase Arrangement – Instead of bonding the full project, the school district could lease the system from a company that would finance and build the system. This model often comes with higher upfront and monthly costs and down the road would require the school district to own and operate its own solar array.
* Public/Private Partnership – With this option, the school district could find a private company to install and maintain the solar facility on its rooftop, and through a Power Purchase Agreement (PPA) pay a discounted rate for only the power produced onsite.
Ultimately, the school district concluded that the most financially sound option was to enter into a public/private partnership with MP2 Capital. MP2 provided the financing for the project and contracted with groSolar to build the system, which is comprised of almost 2,000 panels spanning 40,000 square feet of roof space. (See image below, right.)
Because MP2 is a private, for-profit entity, it could take advantage of numerous tax benefits and incentives that resulted in building the system more cost-effectively than the school district could had it attempted to do so on its own. With this agreement in hand, the school district sought and obtained a $1.72 million grant from the Connecticut Clean Energy Fund, which significantly offset the costs of the solar project. The arrangement with MP2 also allowed the school district to have the benefits of going green without the risk and complications that can come with implementing a solar solution of its own.
By initial counts, the PPA arrangement will save the school district approximately $25,000 in the first year. Those savings could grow if electricity rates in Connecticut continue to rise faster than the fixed escalating rates established in the PPA.
The savings are not the only resulting benefit. The school district received a grant from a large corporation with a local office, Alcoa, which has made a goal of investing in sustainable energy projects through grants. With the Alcoa grant, the school district was able to hire a part-time teacher, who built a curriculum centered on green science and technology, including classes that even utilize data generated from the rooftop solar panels as part of the lesson plan. That teacher also leads a “green schools” group of students, who meet to talk about ecological conservation and renewable energy issues.
Another favorable outcome is the partnership that has developed between the public school district and neighboring Northwestern Connecticut Community College. This partnership resulted in plans for an associate’s degree in Green Technology and Science at the college. Students from both the high school and college campuses take part in these shared classes, which can lead to green jobs for graduating students at a variety of entry levels. This “workforce” initiative is a key spinoff of the implementation of renewable energy programs at Northwestern Regional School District 7. Additionally, because the school district relied on contractors and suppliers in Connecticut, it was able to positively contribute to the local economy in the near-term.
Northwestern Regional School District No. 7 is not alone in leveraging this public/private partnership model for renewable energy projects. Schools across the country – including many in California and Colorado – are utilizing their rooftops and PPAs to go green in an affordable and socially responsible way.
Schools Have a Unique Opportunity
While all of us in the United States should be considering what we could do to reduce reliance on fossil fuels and end global warming, school systems have a unique opportunity to serve as a textbook example for promoting use of renewable energy. Not only can school buildings serve as a showcase for solar or wind projects, the lessons learned by students and the community are perhaps even more valuable when it comes to sustaining interest in and expanding the use of renewable energy resources.
Michael Laine (pictured top, left) is a principal at MP2 Capital. Before joining MP2, he worked in the derivatives documentation department at Barclays Global Investors, and served as the senior news editor at SNL Securities (now SNL Financial) where he was responsible for its coverage of banks, REITs, and insurance companies. He also worked a number of years as a chef and restaurateur.
Mr. Laine holds a J.D. from the University of California, Hastings College of the Law; he earned an M.A., with distinction, in American History from George Mason University and a B.A. in History from the University of Virginia.
Clinton Montgomery (pictured sitting at his desk, left) has worked as a school administrator for thirty years starting as a principal and eventually working up to his current position of superintendent of schools for a regional school district in northwestern Connecticut. Prior to his move to education, Mr. Montgomery worked in the development of psychiatric treatment programs for children and adolescents. He has continued to consult in the areas of program development and bilingual psychology in both Connecticut and New Mexico.
Before gaining postgraduate degrees from the University of Rhode Island and the University of Connecticut, he worked in the sign maker, making carved signs for businesses and boats in Rhode Island.
PowerCost Monitor Goes WiFi: Plus Microsoft’s Hohm Web Portal
- By Guy Marsden
Blue Line Innovations (www.bluelineinnovations.com) released its PowerCost Monitor (full kit, $268), a new energy monitor that couples with Google’s free PowerMeter Web portal (www.google.com/powermeter), entering the market alongside the TED 5000 energy monitor (www.theenergydetective.com). The PowerCost Monitor straps around your utility kWh meter, reading the meter wheel optically. (It also works with digital meters.) Opening the breaker box is not required. Data is sent by Bluetooth to a gateway and your Internet router, which sends it to the Microsoft Hohm free Web portal (www.microsoft-hohm.com). The Hohm portal helps consumers with energy-saving tips, tracks your energy usage and compares it to historical patterns. Plus, you can learn how others have saved money and energy—including your neighbors. Users enter data about their home and energy usage, and Hohm then offers efficiency recommendations. The monitor currently has no provision for reporting grid-tied renewable energy generated or exported, unlike the TED/PowerMeter system.
PURCHASE YOU POWER COST MONITOR TODAY AT WWW.ASOLARPLACE.COM
SunReports Apollo 1 PV & SHW Systems Monitoring
By Chuck Marken
Interested in monitoring the performance of your PV and thermal systems (SHW or pool heating) with the same device? Then check out SunReport’s Apollo 1 (www.sunreports.com). The monitor uses your Internet connection and results can be accessed by any Web browser. For thermal systems, temperature sensors monitor system performance and current transducers detect when the pump is energized. Easy setup features include inverter detection, current transducers, and Internet connections. Plus, the wiring is color-coded. No Internet configurations are needed after correct component installation and wiring.
Apollo 1’s thermal monitoring requires an estimated flow rate; this will rarely be as accurate as a Btu meter working with an inline flow meter, but it’s the next best solution. For more information on SunReport’s PV system monitoring, see “High-Tech Solutions for Keeping Tabs on Your PV System” in this issue.
Brightest Days Ahead for Hybrid Gas-Electric Cars
By Bradley Berman
To paraphrase Mark Twain, recent reports of the death of hybrid cars have been greatly exaggerated.
In the past few months, the reliability and safety of cars that use both a gas engine and an electric motor have been called into question. If you believe the headlines, you’d think that hybrids are running out of gas (and electrons). But a study of product plans from major car makers reveals that hybrids are just getting started.
The worst of the antihybrid press took place in March, when a San Diego, California, man claimed that his Toyota Prius sped up and couldn’t be stopped. After a harrowing 23 minutes—recounted in detail by major national media outlets—a highway patrolman coached the man to safety by having him simultaneously apply the parking brake and foot brake. Investigations by Toyota, the National Highway Traffic Safety Administration, and even NASA, failed to produce any explanations. No matter. The incident struck fear into the public’s hearts and, along with Toyota’s other safety publicity, undermined the once-spotless reputation of these hybrids as the most reliable and fuel-efficient cars on the road.
Hybrids have also come under attack from the other side of the gas-electric divide. At least one auto reviewer sees hybrids as dead in the water now that a new age of electric cars is upon us. In late April, Warren Brown of The Washington Post wrote, “Hybrids are merely a way-station until we get proper electric cars and infrastructure…. The Prius’s dominance seems to be almost over.” Indeed, fans of pure electric cars have a lot to be happy about these days with the Nissan Leaf, Ford Focus Electric, Coda Electric Sedan, Mitubishi i-MiEV, and other EVs scheduled to arrive this year (see “The EV Revolution,” this issue). But electric devotees eager to dance on the grave of any vehicle with an internal combustion engine might have to wait a bit longer.
Most forecasters believe that relatively affordable gaspowered engines—especially ones employing strategies like direct injection and turbocharging—will become increasing efficient and will be a long-term winner when it comes to the economics of saving fuel. Of course, these downsized gas engines can be combined with an electric motor and a battery pack to turn them into hybrids—and boost efficiency even more. In fact, tougher fuel economy regulations requiring automakers to reach an average of 35.5 mpg by 2016 will practically legislate more hybrids.
In the next five years, the number of hybrids—both the ones that can plug in and the ones that can’t—will grow from 25 to perhaps 60 or 70 models.
What should we expect?
* Toyota plans to double hybrid production in 2011, and will introduce an entire family of Prius cars in the next few years. Their plans reportedly include a subcompact Prius, a Prius plug-in hybrid, and a hybrid minivan.
* Ford’s electrification strategy includes the all-electric Ford Focus and Transit Connect, but also the Ford MKZ hybrid (due later this year), a plug-in hybrid Ford Escape, and a pair of next-generation hybrids by 2013. The company is also crossing the pond with a set of hybrids and plug-in hybrids for Europe.
* Hyundai will introduce its first hybrid, the Sonata hybrid, and says that it’s working on a new hybrid to compete against the Prius.
* Honda is re-investing and re-engineering its future hybrids in a quest to take the lead on fuel economy. It will introduce the small and sporty CR-Z hybrid coupe this summer, and use the technology on a hybrid minivan and in its Acura luxury division.
* General Motors is on track to introduce its Chevy Volt, a plug-in hybrid, late this year and will follow with a plug-in hybrid crossover SUV. GM executives continue to assert that mild hybrid technology is a critical strategy for making future hybrids affordable.
* It’s rumored that Mercedes is planning to convert its entire S-class to hybrid technology in the next few years.
* Nissan stands alone in its belief that pure electric cars are a single-point solution. Yet, its luxury division unveiled the Infiniti M35, its first hybrid, at the 2010 Geneva Motor Show. UK’s Autocar reported that all Infinitis will be hybrids within 10 years.
Connect these dots to get a hybrid-rich picture of the road in 2013 or 2014: a 50-mpg Prius next to a 50-mpg Honda, next to a 50-mpg Hyundai, next to a 90-mpg Prius plug-in hybrid, next to the plug-in hybrid Chevy Volt…
Array Voltage Considerations
By Bill Brooks
Source-circuit configuration is arguably the most important aspect of PV system design. The electrical and mechanical characteristics of a PV array follow from this fundamental design decision, which has a bearing on both labor and material costs. In addition, source-circuit configuration impacts system performance, in some cases negatively. Low dc array voltage, for example, is a common cause of substandard performance that occurs when open-circuit or operating voltages for an array persistently fail to meet minimum inverter dc input voltage thresholds over time. In this situation, the system design does not take into account the cumulative effects of a variety of real-world circumstances, including high ac grid voltage, array degradation, module-to-module voltage tolerance and high ambient temperatures. Fortunately, low dc array voltage is avoidable.
In this article, I detail array design best practices for determining the maximum number of modules in a source circuit. My approach is slightly less conservative than the industry standard and is supported by changes to the National Electrical Code that are introduced in the 2011 cycle. I also present recommendations for determining the minimum number of modules per source circuit. While these may be more conservative than current design standards, my opinions are based on years of experience. They are not influenced by the desire to sell more or less of any specific product but rather by the general desire to propagate well-designed PV systems that perform optimally for decades.
CONSIDER THE SOURCE
Interestingly enough, over the past decade inverter manufacturers have been the primary source of education regarding array design and source-circuit sizing. With all due respect, these companies usually have expertise in power electronics and not necessarily in PV array design. However, since the advent of the first string-sizing program—which was developed by John Berdner while he was the president of SMA America—it has become the industry standard for inverter manufacturers to provide PV array configuration advice.
The main drawback to having inverter manufacturers dictate array design is that they have a conflict of interest. Manufacturers want their products to be used as often as possible, and this is facilitated in part by allowing the maximum number of module configurations. In addition, although most manufacturers have stern warnings about exceeding the maximum inverter input voltage, they generally have little to say about circumstances where there is too little voltage for the inverter to fully operate the PV array.
This skewed perspective informs both the string-sizing tools and the training materials that inverter manufacturers develop. The upshot is that inverters in the field seldom have a problem with high array voltage but routinely have problems with low array voltage. While low array voltage will not damage the inverter, it will compromise system performance.
If the inverter cannot operate the array at its MPP, for example, then power production and energy harvest suffer. Problems can also result from open-circuit voltage being too low. On hot days, an array’s Voc can pass below the restart voltage of the inverter. The consequence is that if the inverter shuts down in the middle of the day due to a utility disturbance, it will not restart until the late afternoon when the Voc increases. This can reduce the system’s operating availability by several percentage points annually if utility disturbances are common in the summer, such as when utilities switch in distribution capacitors around noon on hot days to accommodate high air conditioning loads. To design a PV array that is well-matched to an inverter’s operating window, system designers need to pay attention to the low end of the inverter operating voltage range, as well as to the maximum voltage allowed.
HIGH DC VOLTAGE
The maximum dc voltage for an inverter is clearly stated on the product specification sheet, installation manual or in tables, such as the one from the SolarPro article, "Central Inverter Trends in Power Plant Applications". While relevant UL standards and NEC requirements certainly apply, the maximum voltage is generally set by the input capacitors and the ratings of the transistors in the inverter, so it is a constant rather than a variable limit.
Because it is possible to create overvoltage in an inverter by putting too many modules in series, some manufacturers keep the maximum dc input voltage in nonvolatile memory for warranty purposes. This allows the manufacturer’s service technicians to verify the maximum dc voltage input to any inverter that is returned from the field under warranty. If the inverter was exposed to overvoltage conditions, then the manufacturer may choose not to provide a free replacement inverter. Historically, the most common cause of over-voltage is putting two source circuits in series rather than in parallel. This is a relatively easy mistake to make, especially in a small system with only two source circuits. Failure to properly account for low ambient temperatures is another potential cause of inverter overvoltage.
Some inverter manufacturers have claimed in their trainings that a 600 Vdc inverter will spontaneously combust if the array reaches 601 Vdc. While the inverter warranty may be voided if the array goes above the published maximum voltage, it is inconceivable that the capacitor or transistor tolerances are tight enough for the devices to operate well at 600 Vdc and explode at 601 Vdc. If that were true, inverters would also explode at 580 Vdc and they (usually) do not—at least not because of component tolerance.
Low temperature calculation. Most inverter manufacturers recommend using the site’s record low temperature to determine the maximum number of modules per source circuit. While the record low temperature is easily attainable (see “Low Design Temperature,” below), it is also overly conservative for maximum voltage calculations. The record low temperature is usually too conservative for design calculations because temperature is only one of two major factors that impact array open-circuit voltage. The other major factor is irradiance. As an example, look at the set of I-V curves in Figure 1, which assumes constant cell temperature and variable irradiance, and notice where the I-V curves intersect the horizontal axis. As irradiance decreases, so does open-circuit voltage.
The NEC, however, uses temperature only to determine maximum system voltage. The criterion for determining the maximum PV system voltage, according to Article 690.7(A), is to correct the source circuit open-circuit voltage for the “lowest expected ambient temperature.” Prior to the 2011 cycle, the NEC did not define the term lowest expected ambient temperature. However, the 2011 NEC will define it in an Informational Note (formerly known as a Fine Print Note) as follows: “One source for statistically valid, lowest expected ambient temperature design data for various locations is the Extreme Annual Mean Minimum Design Dry Bulb Temperature found in the American Society of Heating, Refrigeration, and Air Conditioning Engineers’ ASHRAE Handbook—Fundamentals. These temperature data can be used to calculate maximum voltage using the manufacturer’s temperature coefficients relative to the rating temperature of 25°C.”
An Informational Note is not a Code requirement and cannot be interpreted as such. System designers can use any authoritative source of data for the lowest expected ambient temperature. However, this Note is intended to help the designer and the AHJ focus on the most appropriate data for balanced array design. Since many system designers may not have ready access to the ASHRAE Handbook, the Extreme Annual Mean Minimum Design Dry Bulb Temperature data—hereafter referred to as the ASHRAE low design temperature data—is included in Appendix E of the Expedited Permit Process for PV Systems document that I wrote for the Solar America Board for Codes and Standards (Solar ABCs). This document is readily available on the SolarABCs website (see Resources) and includes data for more than 650 cities in the US.
Some may ask why ASHRAE data is better to use than the record low temperature. One reason is that using the record low temperature sometimes excludes acceptable source-circuit configurations that may in fact be preferred over shorter source circuits. (This is illustrated in “Case Study: Example dc Voltage Calculations,” below.) In addition, the extra margin of safety that the record low temperature design provides is often statistically insignificant when compared to the ASHRAE design.
System designers must consider three important issues when determining an appropriate design temperature. First, statistically, the record low temperature may never occur again. Second, lower irradiance conditions in winter make it even less likely that peak irradiance (1,000 W/m2) will accompany the record low temperature, which is a necessary coincidence to achieve the calculated maximum voltage based on temperature. Third, to achieve in the field the maximum voltage that is possible on paper, the PV array must be in a condition that is as good as new. The modules cannot be soiled, mismatched or degraded; the maximum voltage for each of the installed modules must equal its published rating. The statistical likelihood of these conditions occurring at the same time is low.
The ASHRAE data provide statistically derived expected low temperatures. Although ASHRAE processes National Weather Service data for use by engineers sizing heating and cooling equipment, the data are also relevant to many other fields, including the electrical industry. The ASHRAE low design temperature data is derived by averaging the annual low temperature for every year on record. The result is a low temperature that has a 50% chance of occurring once a year at a specific location. Statistically, 50% of the years that a PV system is in service, the low for the year will be colder than this value—and for the other 50%, the low will never reach this value.
This does not mean that there is a 50:50 chance that the maximum voltage to the inverter will be exceeded in a given year. Remember that peak irradiance must accompany this temperature, and the modules must perform as if they were new and perfectly matched. Ultimately, engineering design involves a series of decisions based on the likelihood of an occurrence and the consequences should the worst case happen. Good system engineering balances valid concerns to develop a design that keeps all the equipment operating properly within acceptable limits. Using the record low temperature does not eliminate the statistical possibility of exceeding an inverter’s maximum input voltage; it simply lowers the possibility relative to a higher temperature. I recommend using the ASHRAE low design temperature data unless there is a specific need for more conservative design data.