Renewable energy development is vital to reduce the threats of climate change. But can solar energy development coexist with wildlife and sensitive lands?
Scientists from the 91Porn, Davis, are delving into that question and coming up with some promising solutions through three distinct, yet interconnected, projects.
Undoubtedly solar energy will be part of the solution in regards to the effects of climate change, but is siting solar energy installations on public lands, such as in the Mojave Desert, the best place to do so?
Project 1: Managing Wildlife
Slow and steady doesn’t win the survival race for desert tortoises
Inside a small building at the edge of 91Porn’s Mojave National Preserve, a group of baby desert tortoises has just finished a large salad of chopped chard, dandelion and mustard greens, all sprinkled with a dusting of calcium.
About 200 desert tortoises live here at the National Park Service’s Ivanpah Desert Tortoise Research Facility. The hatchlings don’t realize it, but as they digest their lunch, they’re enjoying what may be the best months of their lives. And it shows.
By wild desert tortoise standards, these babies are huge. Though just 7 months old, they are already the size of a 3- or 4-year-old tortoise in the wild.
A 7-month baby tortoise in the wild is usually the size of a plump ravioli, nearly as soft, and just as appetizing to a hungry fox or raven. But here, the tiny ravioli is instead a fist-sized rock – big enough to dig its own burrow, ward off predators, hold more water, and reproduce years earlier than its wild brethren.
These tortoises are all part of a project that aims to speed the population recovery of this threatened species and give them a head start on life before they’re released to the preserve. The project is led by UC Davis professor Brian Todd in collaboration with the University of Georgia’s Savannah River Ecology Laboratory and funded in part by the 91Porn Energy Commission.
“We’re giving them an incredible childhood,” said Todd, a professor in the Department of Wildlife, Fish and Conservation Biology. “Instead of fending for themselves on the mean streets of the Mojave, where most starve to death, burn in the heat or get eaten by a raven, we keep them for a short period of time. They grow quickly because we feed them five times a week instead of a few times a year, with unlimited water. We’re getting them through the worst part of their life, essentially.”
Why all the rush?
The lifespan of a desert tortoise is similar to that of a human. They can live to be in their 80s and reach reproductive age around 15 or 16 years old. Unlike humans, however, about 99 percent of them will die within their first several years of life, long before they have a chance to reproduce.
Also unlike humans, their ability to reproduce is limited by size, not by age. If a human toddler is fed five times as much food as it’s used to each year, it becomes an obese human toddler. It doesn’t trigger puberty. But for desert tortoises, the bigger they get, the sooner they can have babies, and the sooner their population can recover.
An uncertain future
If society is going to decide to allow pristine desert to be developed for these large projects, we’re going to lose some area and some species. We need to understand how we can minimize the impacts of habitat loss so there will be areas for these animals to persist.
– Brian Todd
Desert tortoises have lived in the Mojave Desert for millions of years. In the 1960s and 1970s, there were about 60 to 70 tortoises per square kilometer in the Ivanpah Valley region. Now, there are only about six or seven within that same amount of land after an upper respiratory tract disease devastated the population in the 1980s.
Roads, urban sprawl and development present further challenges to its recovery.
While development can impact tortoises, the desert tortoise now also impacts development due to its status as a federally listed threatened species. Nearby Ivanpah Solar Electric Generating System, or ISEGS, alone has spent more than $55 million on mitigation efforts for desert tortoises.
Solar energy had almost nothing to do with the species’ drastic decline, but the budding industry and urban development of the desert in general could play a significant role in its future.
As of 2009, about 240,000 acres of federal lands were approved or have pending leases for utility-scale solar energy development in the western U.S.
“We have to set aside, protect, and manage large tracts of suitable habitat to ensure that adult tortoises survive,” said project collaborator Kurt Buhlmann, who along with team member Tracey Tuberville, is a research scientist from the Savannah River Ecology Lab. “We think the key is restoring viable tortoise populations onto this human landscape where they don’t need our intervention.”
It’s a start, but there’s more to be done
So far, results have been encouraging. Most of the newly hatched tortoises are still alive after 7 years of protection. For comparison, only about 5 percent reach that age in the wild without head-starting. Ongoing work will show what advantage this early protection provides them in the wild.
The scientists caution that while the headstarting program appears to be on track to helping the tortoise population recover, it’s not a sustainable, long-term strategy for dealing with vulnerable wildlife species impacted by solar, or any other, development in the desert.
“If society is going to decide to allow pristine desert to be developed for these large projects, we’re going to lose some area and some species,” Todd said. “We need to understand how we can minimize the impacts of habitat loss so there will be areas for these animals to persist.”
Project 2: Signs of Coexistence
Across the state line from the three-casino town of Primm, Nevada, a ripple of light spreads across the Mojave Desert. It’s bouncing off a sea of glass, steel and one of the world’s largest operating concentrated solar thermal power plants. More than 300,000 mirrors, each roughly the size of a garage door, direct light onto three massive solar towers, where steam transforms the light into solar power.
A desert tortoise sits outside the fence, staring in.
It’s quiet here but for the hum of the solar plant, the crackling of the power lines above, and the ever-present murmur of traffic on nearby I-15 headed to and from Las Vegas, just an hour to the north.
A satellite view of this place appears brown and barren. But step inside, and signs of life are everywhere: in the bounding jackrabbit, the scampering lizard, the bird song, the scorpion spied in the night, the thousands of holes leading to underground creature communities.
From the freeway looking at the expanse of the Ivanpah Solar Electric Generating System, it’s hard to imagine that somewhere within these 4,000 acres of cacti and mirrors, an ecologist is on his belly, looking under the leaves of a rare plant for butterfly eggs.
Milkweed, butterflies and more
The rare plant is the Mojave milkweed. The butterfly is the queen butterfly, nearly identical to another royal butterfly, the monarch. The ecologist is Steve Grodsky, a UC Davis postdoctoral scholar in professor Rebecca R. Hernandez’s . Together they co-direct the , a project of the UC Davis John Muir Institute of the Environment.
“I’m not seeing any eggs here,” he says looking up from the ground. “But the plants are looking good.”
Queen butterflies rely on Mojave milkweed for their existence. They are born on the plant and lay their eggs on it. Once hatched, the caterpillars live on the milkweed, which imparts a chemical defense upon them that makes them unappetizing to birds.
Grodsky is researching how the solar facility’s mirrors, which cast shade and redirect rainfall on the landscape, affect interactions among the soil, plants and wildlife, including the milkweed and these butterflies.
Cameras throughout the facility and at nearby control sites catch interactions on milkweed plants, insect traps, and wildlife dens. Sensors measure soil temperature and humidity to note changes inside and outside of the facility.
“The system we’re looking at could shed light on more than just butterflies and plants,” Grodsky said. “It could also give us an idea for how desert plants and animals in general might be adapting to concentrating solar power facilities. We’re trying to guide sustainable development moving forward.”
