Ivanpah Solar Electric Generating System Earns POWER’s Highest Honor
The era of Big Solar has arrived, and at the moment there are none bigger than Ivanpah. For overcoming numerous obstacles to build the world’s largest solar thermal plant, the Ivanpah Solar Electric Generating System is awarded POWER’s 2014 Plant of the Year Award.
When the 392-MW Ivanpah Solar Electric Generating System in Nipton, Calif., reached commercial operation in December 2013, with many first-of-a-kind construction elements, it represented a number of significant milestones: The largest solar thermal plant in the world, the first large-scale concentrating solar power (CSP) project in the U.S. to employ power tower technology, and the biggest project funded to date by the Department of Energy’s (DOE’s) Loan Projects Office (LPO).
Now, Ivanpah records another milestone: The first renewable plant to receive POWER’s Plant of the Year Award.
When the facility reached commercial operation, it marked the successful conclusion to a seven-year project that brought together an unusual coalition of industry veterans and newcomers and which—notably for a plant designed from the beginning to limit its impact on the desert ecosystem—faced some unexpected environmental opposition.
Comprising three self-contained units with a total capacity of 392 MW (377 MW net), Ivanpah is a joint effort between BrightSource Energy, NRG Energy (through its subsidiary NRG Renew, formerly NRG Solar), Google, and Bechtel. BrightSource began development in 2006, hoping to leverage its experience in developing CSP technology worldwide. NRG and Google contributed substantial funding, while Bechtel supplied engineering, procurement, and construction (EPC) for the plant. NRG Renew is now the majority owner and in charge of operations for the joint venture.
Few power plants can be called “small,” but nearly everything about Ivanpah is mammoth. The three-unit site sprawls over 3,500 acres—nearly 5 miles from end to end—near Nipton, Calif., about 40 miles southwest of Las Vegas (Figure 1). The facility is large enough to be visible from orbit, and the glow of the three power towers is visible from many miles away when the units are online.
The station uses 173,500 heliostats (each with two mirrors) to concentrate sunlight on the 459-foot towers. The towers were built this high to increase efficiency and reduce the already large footprint of the site; still, the furthest heliostats out are more than half a mile away from their tower. Four types of heliostats were used depending on the distance. All of them were precisely placed using GPS to ensure accurate alignment, and they are capable of withstanding 85-mph winds.
Each tower holds a 2,100-ton Riley Power boiler that directs steam into a Siemens turbine generator at ground level. The boilers retain enough heat from the previous day to start up on sunlight alone, though an auxiliary boiler is used during cold start conditions or when it is desirable to start up the plant earlier in the morning. A 110-ton tuned mass damper is located at the top of each tower to keep it stable in high-wind conditions.
The facility relies on air-cooled condensers supplied by SPX Cooling Technologies to condense the turbine exhaust. This design was selected in order to help Ivanpah use about 95% less water than a wet-cooled thermal plant. In practice, the plant has been even more water-thrifty than expected: Through the first hundred days of operation, it used only 6% of its allotted 100 acre-feet of water, just under 20,000 gallons per day. The plant’s only water needs are boiler makeup and mirror cleaning. Water is sourced from two wells on the site and purified for use.
Ivanpah’s operating parameters are given in Table 1.
Development of the Ivanpah Solar Electric Generating System
Oakland, Calif.–based BrightSource began development of Ivanpah in 2006. At the time, the CSP sector—especially solar towers—was still nascent, with only a few relatively small demonstration projects in operation. But BrightSource already had substantial experience developing solar thermal technology, including the 6-MWt Solar Energy Development Center in Israel’s Negev Desert, which came online in 2008. Ivanpah would follow a similar design—but on a much larger scale. Originally planned for 400 MW, the proposed site at Ivanpah dwarfed those earlier systems.
After selecting the site, BrightSource filed for prequalification for the DOE’s Loan Guarantee Program in December 2006 and submitted its application for certification with the California Energy Commission (CEC) in August 2007.
The design for Ivanpah underwent a number of changes during development. As originally proposed, it would have involved 10 smaller power towers, three each for two 100-MW units and four for a single 200-MW unit. Construction was set to begin in 2009, with completion slated for 2012. As is often the case with power plant development, especially large, groundbreaking projects like Ivanpah, those dates would slip.
In October 2007, BrightSource was invited by the DOE to submit a formal application for a loan guarantee, which was completed the following November. The application proceeded swiftly by DOE standards, and the LPO would give conditional approval for 450.37 billion in loan guarantees (an amount later increased to 450.6 billion) in February 2010.
The site for Ivanpah, on Bureau of Land Management (BLM) land near Interstate 15, was carefully chosen to leverage a number of advantages. Foremost among these was supplying renewable energy to California’s investor-owned utilities, which are required to obtain 33% of their electricity from renewable sources by 2020. Power purchase agreements (PPAs) for Ivanpah’s production were signed with Pacific Gas Electric (PGE, for 118 MW to 126 MW from Unit 1 and 126 MW to 133 MW from Unit 3) and Southern California Edison (SCE, for 126 MW to 133 MW from Unit 2) in 2009.
The Mojave Desert location enjoys some of the highest insolation in the United States (around 2,700 kWh/m2/yr), making it ideal for CSP. It is also close to the 500-kV Eldorado-Lugo transmission line, which supplies electricity to Southern California. This meant that relatively little transmission infrastructure was needed despite Ivanpah’s remote location. Only one new substation and upgrades to an existing substation and a 115-kV line (upgraded to 220 kV) were ultimately needed. Finally, natural gas for backup and startup generation could be supplied from a pipeline just half a mile to the north.
Construction
In September 2009, BrightSource selected Bechtel as the EPC contractor for Ivanpah. In December, Bechtel signed a project labor agreement with the State Building and Construction Trades Council of California and the Building Construction Trades Council of San Bernardino and Riverside counties to ensure that California’s local union workforce would benefit from the project. Ultimately, on-site construction staff would peak at about 2,650, the majority of whom were local.
Meanwhile, the California Public Utilities Commission (CPUC) approved the PPA with PGE in August 2009 and the contract with SCE the following August.
The enormous size of the site and its impact on the desert environment proved to be the first roadblock. Among the concerns was a need to relocate desert tortoises, which are native to the area and federally listed as threatened under the Endangered Species Act, and avoid damage to several protected plant species. In February 2010, BrightSource agreed with the CEC and the BLM to revise the initial design to reduce the overall footprint. This was done largely by reducing the number of power towers from 10 to three. The new towers would also be substantially taller: 459 feet vs. 371 feet (Unit 3) and 262 feet (Units 1 and 2) in the initial design.
This more focused layout would reduce the overall footprint by about 12% and reduce the footprint of the larger Unit 3—where the greatest environmental concerns lay—by about 23%. The new design would have a slightly smaller output but would need 40,000 fewer heliostats (Figure 2).
The new approach passed muster with the CEC, which issued an operating license in September 2010, and the BLM, which approved the project in October. BrightSource and Bechtel broke ground shortly thereafter.
With licenses now in hand, NRG Energy stepped forward to join the project, committing up to 300 million in funding. NRG Renew had been on a shopping spree in California and Arizona, having agreed that June to acquire nine solar development projects from US Solar, an affiliate of Arclight Capital Partners. Ivanpah would be its largest solar project to date.
One last partner would come aboard, but it came from a sector not normally known for investments in power generation. Yet for several years prior, Google had been investing more than 300 million in various renewable energy initiatives, including 10 million in BrightSource. None of its prior solar investments were the size of Ivanpah, however. In April 2011, Google was ready to make a more significant move, committing 168 million to the project.
Google’s investment was part of its goal to spur development of renewable energy. At the time, Rick Needham, Google’s director of energy and sustainability said, “We hope [Ivanpah] can serve as a proof point and spur further investment in this exciting technology.” Google’s contribution helped close financing for the final 5000.1 billion price tag.
Construction of the plant required precise organization and management of many moving parts. The materials alone included 42 million heliostat components, including 22 million rivets, more than 7,500 tons of steel, 1,200 miles of cable, and more than 36,000 cubic yards of concrete.
Installing the 173,500 heliostats according to schedule meant that 500 mirrors had to be delivered to the solar field every day for two years. To make this work, the team devised a special transportation system that would allow the project to meet its delivery targets.
With so much repetition at such a large scale, well-coordinated planning and innovative solutions helped create efficiencies. Equipment was redesigned in order to develop a more efficient way of augering holes and installing heliostat pylons, while allowing the project to better protect the desert landscape and reduce impact to the environment.
Construction of the power towers and boilers represented significant first-of-a-kind elements that tested engineering teams and craft labor. The towers were assembled in sections and in multiple assembly areas in order to maintain the schedule, while the boilers were built in ten 90-ton structures in a common area. Boiler sections were carefully lifted into place with specialized cranes (Figure 3).
Real World Reliability
The FSA/DEIS states: Based on a review of the proposal, staff concludes that the Ivanpah Solar Electric Generating System (ISEGS) would be built and would operate in a manner consistent with industry norms for reliable operation. This should provide an adequate level of reliability (page 7.3-1).
But even for standard solar thermal plant operation we question the placement of this project on an active floodwash fan in a desert with summer monsoon above the average for the western and central Mojave Desert (where other CSP projects such as Daggett Solar 1 and Kramer Junction, are located).
Concentrating solar power needs a sharp sun image to be efficient. It is best done in deserts where there are no clouds or haze. Dust haze scatters light, and image efficiency plummets. Windstorms blow dust off Ivanpah playa frequently, and could lower efficiency for ISEGS. Cloud cover will force the plant to be turned off during winter and summer storms.
Will high winds whipping through the desert rip 20-foot wide heliostats off their bases like sails?
But what surprises us most is the location of the proposal directly below a large rain catchment basin on the slopes of Clark Mountain (look at the photo above). Did the engineers in the city understand desert alluvial deposition processes, or surficial geology and hydrology?
Researchers measured normal rain runoff on a fan below the Providence Mountains, just 60 km south of Ivanpah Valley in Mojave National Preserve, from 2003 to 2006. They found that several winter and summer rainstorms delivered more than 10 mm per day of rain, enough to initiate runoff, and some intense summer storms were greater than 60 mm per hour. These redistributed sand, gravel, and organic debris. High-intensity summer rainfall could last an hour, often exceeding the infiltration rates of the soil (Miller et al. 2009).
This was just over three years. Over the 50-year proposed lifespan of the ISEGS larger storms will occur, possibly as damaging as the flood that hit Furnace Creek in Death Valley National Park, and Surprise Canyon in the Panamint Mountains, California.
Colon 70 model heliostat from PSA project, Almena, Spain.
This is an active sloping alluvial fan, not a stable flatland, seemingly not appropriate for a delicate heliostat array. In describing the engineering of a collector field, Romero-Alvarez and Zarza (2007:21-53) state: Because of the large area of land required, complex algorithms are used to optimize the annual energy produced by unit of land, and heliostats mst be packed as close as possible so the receiver can be small and concentration high. However, the heliostats are individual tracking reflective Fresnel segments subject to complex performance factors, which must be optimized over the hours of daylight in the year, by minimizing the cosine effect, shadowing and blocking, and receiver [light] spillage.
Tracking control mechanisms continuously move the heliostats so that they FOCUS solar radiation on the tower receiver. During Cloud passages and transients the control system must defocus the field and react to prevent damage to the receiver and tower structure (ibid: 21-52).
What if sediments from alluvial runoff tilt several heliostats in the field? Will operators be able to find and correct all heliostat deviations? How long will the plant be shut off while inspections are done after each storm and repairs are made? How much of a tilt would cause tower damage as reflected sun beams are aimed in the wrong direction?
In an investment cost breakdown of building a central receiver solar thermal power plant the heliostat field is the single most expensive part of the project, 40% of total capital costs. The power block comes next, at 32% of total (ibid:21-53).
Yet, Staff believes there are no special concerns with power plant functional reliability due to flooding (page 7.3-6).
Real World Capacity
Utility-scale renewable energy companies like to say how many thousands of houses their power plants will supply, and the newspapers slavishly print these numbers. But they neglect to tell us about capacity factors. The stated wattage, or ‘nameplate capacity,’ is when the sun is shining full-on on a cloudless day. It does not take into account night, short winter days with low sun angle, cloudy and rain days, windy days when the facility will be shuttered, or maintenance (if not done at night). Every generating plant has a capacity factor (the net capacity factor of a power plant is the ratio of the actual output of a power plant over a period of time and its output if it had operated at full nameplate capacity the entire time).
- Thermal solar Without energy storage, the annual capacity factor of any solar technology is generally limited to about 25 percent. Sandia National Laboratories.
- Thermal solar power tower 25%. Abengoa Solar’s large power tower PS10 in Spain, from their brochure pdf.
- Thermal solar parabolic trough ca. 15% average (from Solar Millennium Andasol 1-3 parabolic trough plants in Spain, access date = 2009-05-14). They reported 28% capacity only in peak times.
- Photovoltaic solar in Massachusetts 12-15% (from Renewable Energy Research Laboratory: Wind Power: Capacity Factor, Intermittency, and what happens when the wind doesn’t blow?PDF). Arizona 19% (from Carnegie Mellon Electricity Industry Center Working Paper CEIC-08-04, The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays, by Jay Apt and Aimee Curtright).
- Nuclear 60% to over 100%, U.S. average 92%. Worldwide average varied between about 81% to 87% between 1995 and 2005 (from Renewable Energy Research Laboratory cited above; 15 Years of Progress PDF, World Association of Nuclear Operators, 2006, Retrieved 2008-10-20.).
- Baseload coal 70-90% (from Renewable Energy Research Laboratory cited above).
- Combined cycle natural gas about 60% (from Renewable Energy Research Laboratory cited above). Load-following natural gas plants are turned on only when needed during the higher-demand parts of the day and year, so may have a capacity factor of 42%. When demand for power drops to minimum levels, they are turned off because Baseload power plants designed to run all the time, are already running all the time to provide this minimum demand. Most baseload power plants are coal or nuclear plants.
- Geothermal worldwide average 73%, demonstrated 90% (from Fridleifsson, Ingvar B.; Bertani, Ruggero; Huenges, Ernst; Lund, John W.; Ragnarsson, Arni; Rybach, Ladislaus (2008-02-11). O. Hohmeyer and T. Trittin. ed (pdf). The possible role and contribution of geothermal energy to the mitigation of climate change. Luebeck, Germany. pp. 59-80. Retrieved 2009-04-06).
^New advanced Abengoa Solar power tower PS10 in Spain, with saturated steam cavity receiver. In winds over 22.5 mph the plant must be turned off and the mirrors leveled; over 87 mph and the plant might be destroyed. The Mojave desert is a windy place, but many such power towers are planned.
^Brightsource’s Ivanpah Solar Electric Generating System proposal in California’s Mojave Desert. At over 4,000 acres this plant’s nameplate capacity is only 400 megawatts (MW): with a capacity factor of 25% that would equal 100 MW. Compare this low efficiency to Southern Co./Georgia Power Co.’s Plant Bowen coal-burning power plant which occupies 2,000 acres but puts out 3,160 megawatts maximum at 70-90% capacity. This does not take into account the terrible cost of mountain-top removal mining for coal in the Appalachias, but the question should be asked how solar thermal will replace coal? Desert-top removal is just as bad.
Baseload vs. Peak
Based on reports filed by the nation’s utilities with the Federal Energy Regulatory Commission, about 75% of electricity consumption is baseload and about 25% is intermediate or peak load. Demand is full-time, but wind and solar are part-time.
In the absence of electricity storage, there is no such thing as wind/solar by itself — there is only 30% wind/solar combined with 70% natural gas, or 30% wind/solar combined with 70% coal.
^Intermittent power: Real power output (kW) sampled with one minute resolution for a 4.6 MW solar photovoltaic array in northeastern Arizona for one week (from Carnegie Mellon Electricity Industry Center Working Paper CEIC-08-04, The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays, by Jay Apt and Aimee Curtright).
Finances for the renewable project from Google, Alstom and DOE
The project is being financed through debt and equity. Equity investors apart from BrightSource include Google and NRG Solar, who are financing 168m and 300m respectively.
Alstom is providing 50m in equity funding. Other equity investors in the project include Silicon Valley Venture Capital, Morgan Stanley, BP and Chevron. The California State Teachers’ Retirement System is also investing in the project.
The US Department of Energy (DOE) is providing a 450.6bn loan guarantee to the project.
The project is also backed by the US Government which has promised to provide tax credits equivalent to 30% of the project cost, under the American Recovery and Reinvestment Act (ARRA).
Structure of the Ivanpah solar power facility and heliostat details
The Ivanpah solar complex consists of three plants – Ivanpah 1, 2 and 3, which will run at 126MW, 133MW and 133MW capacities respectively. Each plant will have a 225m tall boiler tower which receives the radiation that will be focused by heliostat mirrors. The complex will have 173,500 heliostats with a total of 347,000 mirrors.
Each heliostat will comprise of two glass mirrors, a support structure, pylon and a software-based tracking system. The heliostats will be asymmetrically arranged in an arc fashion around each tower.
A natural gas-fired start-up boiler will provide the required heat for the plant start-up. Natural gas will be supplied by a gas plant located adjacent to the site.
Each plant will have a steam turbine generator at the base of the tower to produce electricity using the steam generated by the boiler.
Air-cooled condensers will be used to cool the towers in order to minimise the usage of water.
Two wells dug to the east of Ivanpah 2 will supply the required water to the complex. A small onsite waste water treatment plant will also be built. Wastewater will be recycled for zero water discharge.
LPT technology used in the world’s largest concentrated solar plant
The boiler towers at the solar plant will use BrightSource’s Luz Power Tower technology (LPT). Heliostat mirrors fixed on the boilers on top of the towers receive the reflection of the sunlight from those at the bottom of the tower.
This creates high temperature in the boiler, which heats up the water inside the boiler to generate steam of up to 550 degrees centigrade. The steam will be transferred through pipes to the turbine chamber to drive the turbine blades and to produce electricity.
The dry-cooling technology used at the plant reduces the water needed for cooling by 90%. It is estimated that the plant will require just five percent of the water used in conventional solar thermal technologies.
Grid Connections for Ivanpah 1, 2 and 3 and environmental impacts
The three Ivanpah solar plants will be connected to a new substation (to be built), from where the power will be transmitted to the California Power Grid through the Southern California Edison 115kV system.
The project will reduce carbon emissions to the extent of 400,000t a year. It will also complement the state of California’s target of achieving 33% renewable energy by 2020.
The possible harm to the desert tortoises at the project site will be mitigated by acquiring a 7,300 acre land, to where the species will be migrated after onsite disease testing.
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And the road goes on forever
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Ivanpah, California power station just outside of Vegas.
Click link for drive-by video
Abdullo Ashurov сейчас здесь: Ivanpah Solar Electric Generating Facility.
Нерӯгоҳи барқи офтобии Иванпаҳ дар Аёлати Калифорния. Дар роҳ ба Невада ва шаҳри Лас Вегас. Мегӯянд самаранокии ин гуна нерӯгоҳҳо аз панелҳои офтобӣ хеле бештар аст. Аммо то чӣ ҳад аз нигоҳи иқтисодӣ бунёди чунин нерӯгоҳҳо дар Тоҷикистон судовар аст, маълум нест. Шояд пажуҳише дар ин робита анҷом шуда бошад кӣ медонад?
Found another cool landscape feature on my flight today. The Ivanpah System. You might remember them if you saw the movie Saharah with Matthew McConaughey.