Ivanpah Solar Power Facility

Description

The Ivanpah Solar Electric Generating System consists of three solar thermal power plants on a 4,000 acres (1,600 ha) tract of public land near the Mojave Desert and the California—Nevada border in the Southwestern United States near Interstate 15 and north of Ivanpah, California. The site is visible from adjacent Mojave National Preserve, Mesquite Wilderness, and Stateline Wilderness.

The facility consists of fields of heliostat mirrors focusing sunlight on receivers located on centralized solar power towers. The receivers generate steam to drive specially adapted steam turbines. For the first plant, the largest ever fully solar-powered steam turbine-generator set was ordered, using a 123 MW Siemens SST-900 single-casing reheat turbine. Besides steam-turbine generators Siemens supplied instrumentation and control systems. Final approval was gained in October 2010. On October 27, 2010, California Governor Arnold Schwarzenegger, Interior Secretary Ken Salazar, and other dignitaries gathered in the Mojave Desert to officially break ground on the project. The project generated controversy because of the decision to build it on ecologically intact desert habitat.

The project has received a $1.6 billion loan guarantee from the U.S. Department of Energy. The total cost of the project is about $2.18 billion. The facility has contracts to sell about two-thirds of the power generated at Ivanpah to PG&E, and the rest to SCE.

The largest investor in the project is NRG Energy, a generating company based in Princeton, N.J., that has put in $300 million. The project has also received an investment of $168 million from Google, but in November 2011, Google announced that they would no longer invest in CSP due to the rapid price decline of photovoltaic systems, and stopped its research on the project.

Awards

In August 2014, Ivanpah was awarded the "Plant of the Year" award from POWER Magazine. In February 2012, Ivanpah was awarded the CSP (Concentrating Solar Power) Project of the Year by Solar Power Generation USA.

Power towers

The Ivanpah plants use BrightSource Energy's "Luz Power Tower 550 technology" (LPT 550):

The LPT 550 solar system produces electricity the same way as traditional power plants – by creating high temperature steam to turn a turbine. BrightSource uses thousands of mirrors called heliostats to reflect sunlight onto a receiver being developed by Riley Power Inc. filled with water that sits atop a tower. When the sunlight hits the receiver, the water inside is heated and creates high temperature steam. The steam is then piped to a conventional turbine, which generates electricity.

Additionally, "the power towers have 'receiver units' at their top on which the mirror fields focus their reflected light. During operation, these receiver units become extremely hot, such that they glow and appear brightly lit.... Because they are high above the ground, these glowing receiver units will be a visible distraction to persons at many of the KOPs [Key Observation Points], including travelers utilizing I-15."

According to the State of California Energy Resources Conservation and Development Commission Opening Briefs regarding this project, "the project itself is visually imposing. It would cover roughly 4,000 acres (1,600 ha), most of which would be covered with mirror fields. The panoramic expanse of mirror arrays would present strong textural contrast with the intact, natural character of the desert floor [and] would rise to a height of roughly 459 feet [140 m]; an additional 10 to 15 feet [3–5 m] above that height would consist of lighting to meet Federal Aviation Administration (FAA) requirements."

Fossil fuel consumption

The plant requires burning natural gas each morning to get the plant started. The Wall Street Journal reported: "Instead of ramping up the plant each day before sunrise by burning one hour’s worth of natural gas to generate steam, Ivanpah needs more than four times that much." On August 27, 2014, the State of California approved Ivanpah to increase its annual natural gas consumption from 328 million cubic feet of natural gas, as previously approved, to 525 million cubic feet. In 2014, the plant burned 867,740 million BTU of natural gas emitting 46,084 metric tons of carbon dioxide, which is nearly twice the pollution threshold at which power plants and factories in California are required to participate in the state’s cap and trade program to reduce carbon emissions. If that fuel had been used in a modern combined cycle gas plant, it would have generated about 124,000 MW·h of electrical energy. That is enough to power the annual needs of 20,660 Southern California homes. Ivanpah used that gas plus solar energy to produce 524,000 MW·h of electrical energy (more than four times that of the referenced CCGT plant), all while operating at well below its expected output. 2015 showed higher production numbers, with Q1 increases of 170% over the same time period in 2014.

In 2015 the natural gas consumption had decreased to 564,814 million BTU, while the total energy output had increased to 652,300 MW·h.

Ivanpah Solar uses three Rentech Type-D water tube boilers and three night time preservation boilers. The California Energy Resources Conservation and Development Commission approved for each a stack "130 feet high and 60 inches in diameter" and consumption of 242,500 ft³/h of fuel.

Economic impact

BrightSource estimated that the Ivanpah facility would involve some 1,000 jobs at the peak of construction, 86 permanent jobs, and total economic benefits of $3 billion.

Elected San Bernardino County Supervisor Brad Mitzelfelt, who represents most of the California Mojave Desert stated that the "project would create jobs for mostly Las Vegas and electricity for mostly San Francisco".

The project received a $1.6 billion loan guarantee from the United States Department of Energy. The estimated construction costs for the project ($5,561.00 per kW) fall between the construction costs for coal and nuclear power plants, according to Synapse Energy Economics, but this does not account for the less favorable capacity factor of solar power.

It was reported in November 2014 that the investors in the plant were applying for a $539 million federal grant to pay off their federal loan.

Performance

In June 2015, The Wall Street Journal reported: "15 months after starting up, the plant is producing just 40% of [its expected more than a million megawatt-hours of electricity each year], according to data from the U.S. Energy Department." Performance improved dramatically in the second year, as CleanTechnica reported regarding units 1 and 3 that "In 2015, PG&E customers received about 97% of Ivanpah’s contracted electrons, which is a massive improvement over its first year."

The steam plant is designed for 28.72% gross efficiency.

The local irradiance near this area is about 7.4  kW·h/m²/day (annual average) for a total solar energy flow in the visible spectrum of 2.717 MW·h/m² yearly.

A claimed capacity factor of 31.4% implies that the plant would operate for 365 days × 24 hours × 31.4% = 2751 hours per year. At 377 MW (net nameplate capacity) constant power, this means a generation of 377 MW × 2751 h/y = 1,037,127 MW·h/y rounding up to 1.04 TWh/y. Whereas energy storage capacity is missing, it is not clear how a 31.4% capacity factor should be attained, unless a heavy natural gas contribution is taken in account.

Based on 2015 data, the 3 fields combined for a Capacity Factor of only 19.7%.

One heliostat mirror is a 75.6 square feet (7.02 m²) reflecting surface, for a total of 151.2 square feet (14.05 m²) per heliostat. Total plant heliostat reflecting surface results in 173,500 heliostats × 14.05 m²/heliostat = 2,437,144 m². Based on irradiance, the intercepted solar energy flow is 2.717 MW·h/m²/year × 2,437,144 m² = 6,621,720 MW·h yearly. Thermal yield, after taking into consideration reflection, transmission, radiation and absorption losses, assumed about 55%, resulting in a thermal power input to the steam turbines of 6,621,720 MW·h × 55% = 3,641,946 MW·h_th. Resulting expected energy output would be 3,641,946 MW·h_th × 28.72% efficiency = 1,045,967 MW·h/y, rounding up to 1.05 TWh/y. Overall energy conversion efficiency = energy output / intercepted solar energy = 1,045,967 MW*h/yr / 6,621,720 MW*h/yr = 0.15796 or less than 16%.

These calculations are theoretical, because the facility is lacking a storage system, and each night it cools, requiring every morning a preheating ramp-up step. If the preheating is made with natural gas the estimated values are possibile.

May 2016 industrial accident

A small fire was reported on 19 May 2016 when misaligned mirrors reflected sunlight into a level of Unit 3 tower not designed to collect power, shutting down the tower for repairs. As another of the three power-generating units was already offline for scheduled maintenance, the plant was left with only one third of its installation functional. Unit 3 resumed operation on June 8, 2016, within three weeks of the incident. All three units seemed back in operation by June 20, 2016. Solar thermal electricity production in California peaked at 703 MW on that day, up from 452 MW on June 7 when two units were offline.

Environmental impacts

The Ivanpah installation was estimated, before operations started, to reduce carbon dioxide emissions by more than 400,000 tons annually. It was designed to minimize impacts on the natural environment compared to some photovoltaic solar facilities because the use of heliostats does not require as much grading of the land. However, the facilities are fenced off to keep some terrestrial wildlife out, and initial studies indicate that birds face the risk of collision with the heliostat mirrors or from burning in solar flux created by the mirror field.

In 2012, the National Parks Conservation Association (NPCA) issued a report on the project, citing water concerns, damage to visual resources, and impacts on important desert species. In order to conserve scarce desert water, LPT 550 uses air-cooling to convert the steam back into water. Compared to conventional wet-cooling, this results in a 90 percent reduction in water usage. The water is then returned to the boiler in a closed process.

Another potential issue that has been reported is the effect of mirror glare on airplane pilots.

Desert tortoise

The Ivanpah Solar power project was built on six square miles of public land in the south central Mojave Desert. Project construction was temporarily halted in the spring of 2011 due to the suspected impacts on desert tortoises. Construction resumed when the United States Fish and Wildlife Service (USFWS) found the project was not likely to jeopardize the endangered desert tortoise. BrightSource also installed fencing to keep wildlife out of the area. In 2010, the project was scaled back from the original 440 MW design, to avoid building on the habitat of the desert tortoise.

Many desert tortoises found on the site were relocated to other parts of the Mojave Desert; however, environmentalists raised concerns that relocated tortoises were more likely to die due to the stresses involved.

Birds

During the trial of the plant in September 2013, 34 dead birds were found at the plant, 15 of which had heavily burned feathers, which staff at the plant referred to as "streamers" because they were burned in flight by the intense radiation from the heliostat mirrors. From February through June 2014, a team of biologists monitoring the number of bird deaths reported a total of 290.

According to a USFWS report in April 2014, 141 birds, including peregrine falcon, barn owl and yellow-rumped warbler were collected at Ivanpah in October 2013 and 47 of the deaths were attributed to solar flux. According to a report by the Associated Press, "Ivanpah might act as a 'mega-trap' for wildlife, with the bright light of the plant attracting insects, which in turn attract insect-eating birds that fly to their death in the intensely focused light rays." Possible bird kill mitigation strategies are being considered, such as using proven, environmentally safe technologies such as avian radars and LRADs to keep birds away from the site, covering ponds to discourage waterbirds from loitering, and clearing additional land around the plant to make it less attractive and more visible to birds in flight.

In April 2015, "biologists working for the state estimated that 3,500 birds died at Ivanpah in the span of a year, many of them burned alive while flying through a part of the solar installment where air temperatures can reach 1,000 degrees Fahrenheit [540 °C]", reported the Wall Street Journal.

In late 2015, Brightsource released the results of the first full year of monitoring bird and bat deaths at the Ivanpah solar plant. The company reported that during a year of study supervised by the California Division of Wildlife, the number of observed bird deaths, adjusted upward to account for inefficiencies of the carcass-counting, arrived at an estimated 3,500 bird deaths per year caused by the Ivanpah solar plant. The Ivanpah plant has taken steps to further reduce bird deaths.

The initial reports of high avian casualties have been disputed ever since initial reports surfaced: in September 2014, for example, Renewable Energy World suggested "With its claim of 28,000 dead birds from Ivanpah, the Associated Press syndicated a story on every front page in America, spreading alarm about concentrated solar power (CSP) plants, which was not grounded in facts, but on one opponent's speculation."

In September 2016, federal biologists said about 6,000 birds die from collisions or immolation annually while chasing flying insects around the facility’s towers.

Production

Ivanpah Solar electric production is as follows (values in megawatt-hours MW·h).

Ivanpah Total

Ivanpah was advertised as designed to produce 940,000 MW·h of electricity per year, based on its nameplate capacity and assumed capacity factor. In its second year of operation, Ivanpah's production of 653,122 MW·h of net electricity was 69.5 percent of this value, ramping up from 44.6 percent in the first year. In its third year, the annual production was 74.8% of its advertised value.

Fossil fuel use

Ivanpah Solar use of gas is as follows, expressed in MMBtu as reported.

Ivanpah Total

NR = Not Reported (yet)