Seeing the Forest for the Trees
Todd Dawson’s field equipment always includes ropes and ascenders, which he and his team use to climb hundreds of feet into the canopies of the world’s largest trees, California’s redwoods. It’s laborious work, but he’ll soon be getting a little help. From drones.
Dawson, a professor of environmental science, policy, and management (ESPM) and of integrative biology, has teamed up with a company called Parrot to test using drone-based research tools to monitor the Sierra Nevada’s giant sequoias more intensively. The new tools will help him learn how the trees utilize water and sunlight, as well as predict how they will deal with a warmer Earth and changes in water supply.
The need is urgent, Dawson said. Since 2010, more than 102 million trees, mostly pines and firs, have died in California because of drought—62 million in 2016 alone. Dawson and others wonder why the pines and firs are succumbing while thousand-year-old sequoias survive, and whether that trend will continue.
Dawson and Gregory Crutsinger, a plant ecologist and the head of scientific programs at Parrot, performed their first test on a “quadcopter” drone, which is equipped with a state-of-the-art multispectral camera that takes photos in red, green, and two infrared bands. Called the Sequoia, the camera works like more expensive satellite and airborne sensors, measuring the sunlight reflected by vegetation in order to assess physiological activity or plant health.
“Before, a team of five to seven people would climb and spend a week or more in one tree mapping it,” Dawson said. “With a drone, we can do that with a two-minute flight. We can map the leaf area by circling the tree, then do some camera work inside the canopy, and we have the whole tree in a day.”
After the data and photos were stitched together by a software program called Pix4D, Dawson and Crutsinger ended up with a three-dimensional representation of the foliage that Dawson’s team had never seen before—information that will be used to determine how much carbon the tree takes up each day and how much water it uses. This will provide the basis for assessing what might happen with higher carbon dioxide levels in the atmosphere and less water on and in the ground.
“With repeat flights, you can watch a forest grow without ever actually measuring any trees in the forest,” Dawson said. “I think drone technology holds a lot of promise to do some very innovative science over time and in three-dimensional space with a relatively cheap tool. It’s really pretty amazing.”
Tree Mortality Testimony
ESPM professor Scott Stephens spoke at the Little Hoover Commission’s public hearing on California forest management in Sacramento in January. He provided background on the causes and magnitude of tree losses happening throughout the state, and he offered suggestions for both legislation and forest management techniques that could restore resilience to California’s forest ecosystems.
Gaming the Grid
As the clean-energy economy grows, sustainable sources of electricity are being added to power grids around the world at an increasing rate. Keeping those grids stable and affordable through “renewables integration” has become an urgent challenge. But experts are concerned that necessary grid improvements could be slowed or blocked by an inadequate power-engineering workforce or by uninformed voters or lawmakers.
While studying energy-system modeling with the Energy and Resources Group, Michael Cohen, PhD ’16, wanted to help inform the public about what it means to add clean energy to our power grids. Taking inspiration from “edutainment” simulation video games like the SimCity series, he created Griddle, a PC game that enables players to design, operate, and grow their own power grids. Players tackle real-world challenges like meeting California’s renewable energy regulations while controlling costs or stabilizing Japan’s power system in the aftermath of the 2011 earthquake and tsunami. In the process, they learn about the historical operation of traditional power systems, as well as changes triggered by new technology and environmental awareness.
Cohen also developed a high school curriculum to accompany the game prototype and tested both at local schools. He noticed that students wanted to dive into the game quickly, jumping ahead of his planned levels to add wind and solar energy sources early on. “From a values perspective, that was very exciting!” he said. But students had difficulty managing blackouts and controlling costs, Cohen added.
“They learned about the complex realities of adding renewables, from the intermittency of wind and solar power to the cost of implementation.” And he hopes that intrigued them. “I want more people to see that the migration to more sustainable energy sources is a challenge, yes, but an interesting and exciting one.”
Cohen is now working as a power-systems engineer for the Union of Concerned Scientists. He hopes to find more funding to further develop Griddle and eventually make it more widely available.
Powered-up Poo: Turning Feces Into Fuel
Electricity generated from the world’s collective human feces could power up to 138 million households in developing countries, according to research by the United Nations University Institute for Water, Environment, and Health. In September 2014, a Kenya-based company, Sanivation, began commercially treating human waste with the heat of the sun to create an environmentally friendly fuel source. And in August 2016, the company launched a new continuous-flow system that will enable it to take in non-sewered waste from numerous sources.
The treatment process begins with the collection of fecal waste from in-home, dry container-based toilets distributed by Sanivation and ends with a fuel briquette. A reflective parabolic disk acts like a solar concentrator with a heating fluid, continuously heating the feces within a screw conveyor.
The waste is sanitized as the heat removes harmful pathogens. Although research shows that pathogens disappear once the waste has been heated to 60 degrees Celsius (140 degrees Fahrenheit) for one hour, Sanivation errs on the side of caution and keeps it at 60 degrees Celsius for three hours. New research suggests that waste might be effectively treated in mere seconds at 80 degrees Celsius.
The company has been processing less than one metric ton of waste every month, but hopes to increase its capacity dramatically in the months ahead. “The continuous-flow system has allowed us to scale up quite a bit,” said Sanivation chief technology officer Emily Woods, a PhD student in the Energy and Resources Group (ERG). “We’ll soon be able to accept waste from other sources, not just our own distributed lavatories. We want to be an on-site waste treatment provider in areas that don’t have their own treatment options.”
What’s more, Sanivation can now put its newer, more compact equipment in shipping containers for transport to more remote areas. For example, it recently installed a treatment system with a capacity of up to 6 metric tons of waste a month in the Kakuma refugee camp—home to refugees from South Sudan and Somalia. The team hopes to get the system processing over 10 metric tons per month by 2018. While Sanivation has focused on selling briquettes to small businesses and restaurants first, because they use larger quantities, the company plans to expand into the retail household market as well.
“Sanitation impacts every aspect of developing communities—from health to gender to livelihoods to environmental sustainability,” Woods said. “Until now, less than 5 percent of human waste in Kenya has been treated properly before being dumped into the environment. I believe that by solving this problem in a cost-effective manner, we can help communities to grow in a positive way.”