Concentrating Solar Power Under Fire

The Ivanpah CSP plant brought online in January has been heavily criticized for its environmental impacts, namely solar glare.

Utah, USA -- Currently the world’s largest solar thermal plant, the Ivanpah Solar Electric Generating System has been in full operation less than two months and already concerns have been raised about its environmental impacts. Complaints from pilots flying near the concentrating solar power (CSP) plant state that on numerous occasions, the intense reflective glare coming from the plant’s heliostat mirrors has caused pilots to become momentarily blinded. Ivanpah is located roughly 40 miles from McCarran International Airport in Las Vegas, and approximately 25 miles from the Jean Sport Aviation Center in Jean, Nevada.

While it might be easy to dismiss this issue as a “glaring” oversight on the part of its planners (Ivanpah is owned by BrightSource Energy and NRG Energy) further investigation reveals that issues of glint and glare from the plant’s reflective arrays were addressed during the Application for Certification submitted to the California Energy Commission in 2007. The first detailed analysis was included in a 2008 response from CH2M HILL to the CEC’s review of the application.

In their response, CH2M HILL stated that beam safe intensity calculations had been performed and that “the likelihood of random heliostat beam hazard to aircrafts flying in the area is infinitesimally remote.” CH2M HILL is a Colorado-based engineering company contracted by state and federal agencies for design and construction consultation.  CH2M HILL has offices in Bellingham and Bellevue, WA.

Subsequently, the Heliostat Positioning Plan and Tower Luminance Plan, which described even greater analyses of potential glare hazards, was submitted in 2013.

Frank “Tex” Wilkins, executive director of the Concentrating Solar Power Alliance and formerly of the Department of Energy, said the conversation about glare and CSP plants is not a new one. Wilkins took part in discussions in 2009 that looked into the issue. “The FAA convened a panel,” Wilkins said, “where extensive studies were performed on the topic. The final determination was made that glare from CSP plants, in particular glare from power towers, would not create an issue for pilots.”

Cause and Effect

Although it has been reported elsewhere that the incidents may have occurred as a result of pre-launch testing and repositioning of heliostats that took place in August of 2013 — which coincides with the same time frame during which two complaints were filed with the Federal Aviation Administration's Aviation Safety Reporting System — Clifford Ho of Sandia National Laboratories’ Concentrating Solar Technologies Department thinks otherwise.

“I believe some of the glare that’s being viewed is taking place when the heliostats are in a standby mode,” Ho said.

During peak daylight hours, it is common for a number of heliostat mirrors to be taken offline to prevent heliostats from directing more thermal energy to the turbine than it is capable of receiving. Ho said that during standby, these heliostats are focused on aim points next to the receiver, forming a ring of glare above the tower.

According to Ho, the sunlight reflected from heliostats that are in standby mode could be having an exacerbating effect on the amount of reflection being emitted.

In examining photos of the glare taken by passengers flying over the Ivanpah plant, Ho said it’s apparent to him the intense light is emanating from the heliostats not in use. “You can clearly see the difference between what’s just the diffuse reflection from the towers versus one or more heliostats that are in standby mode and reflecting light toward the observer.”

Ho has performed helicopter surveys of heliostats in standby mode at Sandia National Laboratories’ National Solar Thermal Test Facility. “It’s bright,” he said, emphasizing that the Sandia CSP array is much smaller than that of Ivanpah. “When you’re close, it can be like looking into the sun.”

Requests for Remedy and Possible Solutions

On March 10, the Clark County Department of Aviation (CCDOA) sent an official notification of complaint to BrightSource Energy, the California Bureau of Land Management, and the California Energy Commission. In the docket, the CCDOA requested that BrightSource take a number of actions to “respond to and address any complaints about adverse visual impacts to pilots.”

Included in the docket are requests for BrightSource Energy to take measurements of any observed glare and to determine if that glare is within the “maximum permissible exposure.” Ho indicated plans are already in motion to respond quickly.

“We will be doing some additional monitoring of the glare at the site,” Ho said. In addition to helicopter surveys of the area surrounding the Ivanpah plant, ground-based evaluations will also be performed.

One possible solution, as suggested by Ho, is to reposition heliostats that are in standby mode so that they stand vertically — thus reflecting the glare toward the ground instead of upward. Regardless of whether that’s done, Ho believes it is imperative that pilots are briefed on the location of the plant so that they will be aware of potential glare issues.

Ian Gregor, Public Affairs Manager for the Pacific Division of the FAA, concurs. “The FAA is aware of potential glare from concentrating solar plants and is exploring how to best alert pilots to the issue,” Gregor said. “The final Environmental Impact Statement for the Ivanpah project includes mitigation measures that address the issue of glare, which the aviation community raised during the EIS process.”

Sandia National Laboratories currently offers a Solar Glare Hazard Analysis Tool that Ho helped to create, which he says is fundamental to preventing similar issues from arising in future solar development projects. “The solution is to be aware of the potential issues of glare during the planning stage, to ensure it doesn’t become a hazard.”

Source: Vince Font, Contributing Editor, Renewable Energy World 

Record-Shattering Solar

California’s record-breaking solar power generation run continues, solar desalination cleans up dirty irrigation runoff, NASA’s bad Ivanpah map causes flap

Another day, another solar power generation record shattered on the California grid. As Herman Trabish notes at Greentech Media, during the early afternoon of March 16, the use of solar as measured by the California Independent System Operator (CAISO) reached 4.14GW—breaking the previous record set the day before, which broke the record set the day before that, which broke the record set 6 days week before that. (Do I sound like a broken record?) About 5.23GW of installed solar capacity are available to the grid operator, and another 1.1GW of rooftop doesn’t even get counted, according to GTM. The string of broken records–which will likely continue as the days get longer and more PV and CSP come online—has caused CAISO to change its policy of announcing every 50MW record-busting uptick to the 500MW level going forward. More data and details about other renewables and their impact on the California grid make the post even more read-worthy.

Speaking of a good read, an article by Kevin Fagan in the San Francisco Chronicle (via SFGate website) features the compelling tale of WaterFX’s parabolic-trough “concentrated solar still” desalination pilot plant in the agricultural heartland of California’s Central Valley. The facility “has been turning salty, contaminated irrigation runoff into ultrapure liquid for nearly a year for the Panoche Water and Drainage District,” according to the media outlet. “It’s the only solar-driven desalination plant of its kind in the country. Right now its efforts produce just 14,000 gallons a day. But within a year, WaterFX intends to begin expanding that one small startup plant into a sprawling collection of 36 machines that together can pump out 2 million gallons of purified water daily.” Given California’s droughty water crisis and the broader need for solar-powered desal plants in other corners of the globe, the startup’s intriguing, cost-competitive approach bears watching.

Desert defender Chris Clarke of the KCET Rewire blog casts a wary eye in his latest post on that other, much larger, and more notorious concentrating solar thermal plant, Ivanpah. Though a huge supporter of renewable energy in general, Chris is a consistent critic of utility-scale solar farms sited on ecologically sensitive lands. This time, his article actually takes NASA to the woodshed, because of a poor bit of mapping on the agency’s Earth Observatory website. Apparently, in a map of Ivanpah shown on the site, the location of the CSP plant is depicted incorrectly. The solar project “was not built ‘within Ivanpah Dry Lake,’ AKA ‘the playa.’ The project is actually several miles uphill from the barren dry lake, on an alluvial fan once teeming with wildlife. A half-trained eye could look at the Landsat image and see that’s so.”

Chris goes on to elaborate in detail why the distinction between the two locations is important. He notes that solar developers would not want to build a system in a dry lake bed and that alluvial desert areas—like the terrain where much of Ivanpah is located–are much richer in plant and animal life than the “playas.” Although he says NASA “may not have intended to downplay the site’s ecological significance,” its mistake “reinforced the spin of those who do so intend.” Whether one agrees with Chris’s vigorous environmentalist stance or not, his voice is a welcome counterbalance to those in the solar and renewables industry who, in the name of progress and the fight against climate change, downplay the possible impacts of major PV and CSP deployment on the delicate desert ecosystem.

Source: http://www.solarcurator.com/