In his lab at Washington University in St. Louis, researcher Himadri Pakrasi shows another researcher some of the cyanobacteria colonies that have been engineered to produce higher amounts of hydrogen. (illustration credit ill.8)
YOU’VE PROBABLY CALLED it scum. But that slimy blue-green goo floating in ponds and on the ocean comes from a group of species so hardy that humanity’s fumbling attempts to adapt to our environments would be a joke to them. Well, it would be if these blobs of raw biological productivity had a mean sense of humor, or brains, or even mouths to laugh with. We’re talking about our old friend cyanobacteria, whom we met billions of years ago, in the first chapter of this book. At that time, it was busily unleashing enough oxygen to transform the composition of Earth’s atmosphere. Its subsequent 3.5-billion-year career as a life-form proves that this ancient breed of scum has gotten something fundamentally right. Cyano, as it is fondly known among scientists, evolved one of the planet’s greatest adaptations: photosynthesis, or the ability to convert light and water into chemical energy, releasing oxygen in the process.
Cyano has also had a secondary career as a biological building block for other life-forms. About 600 million years ago, sometime before the first multicellular life appeared, cyano began forming symbiotic relationships with other organisms, slowly merging with them over the millennia. Eventually these early cyano evolved inside other cells to become chloroplasts, tiny organs (known as organelles) that handle photosynthesis for plant cells. Every plant on Earth is, in fact, the result of this merging process. You can think of chloroplasts as both engines and batteries for plant cells; photosynthesis creates forms of energy that plants can use immediately as well as store for later. Cyano’s great adaptation is so powerful that plants and even a few animals like sea anemones have survived by absorbing cyano and turning it into their own adaptation.
Brett Neilan, a biologist at the University of New South Wales, has spent his life studying cyano among the ancient rocks of Australia’s coastline, and he thinks the secret to the algae’s success is simple. Cyano’s ancestors won the evolution game because they worked with what the Earth always had in good supply: sunshine, or some form of light, and water. Like most plants, cyano are called autotrophs, a word that means “self-feeding,” and refers to their ability to feed themselves without consuming other organisms. In a sense, cyano generate the food they consume. As a result, they can and do live everywhere. They’ve been found in Antarctica and in the boiling, acidic waters of Yellowstone’s geysers. Not only are they seemingly impervious to dramatic temperature changes, but they are virtually immune to famine as well. According to Neilan, cyano prevent themselves from starving in times of scarcity by storing extra nutrients like nitrogen in little sacs tucked inside their cellular walls. If these food caches are not enough, cyano can go into stasis. The microbes put themselves into a kind of suspended animation and can endure without food for years, waiting out droughts or other disasters that affect their food supply.
Cyano have other incredible abilities, too. They can live as individual single-celled organisms, but they can also join together with other cyano, Mighty Morphin Power Rangers–style, to form a multicellular creature. They are the simplest organism on Earth whose biological processes are regulated by the circadian rhythms of light and dark. Like humans, with our sleeping and waking cycles, cyanobacteria engage in different metabolic activities depending on whether it’s day or night. This allows them to engage in two separate chemical processes for nourishment—photosynthesis and nitrogen fixation—which would normally interfere with each other. Thanks to their circadian clocks, cyano can do photosynthesis by day and nitrogen fixation by night. They thus benefit from two kinds of nutrient production. Other plants benefit, too. Just as some organisms absorbed cyano to create choloroplasts, others have formed symbiotic relationships with the bacteria to reap the benefits of the energy produced by nitrogen fixation.
Cyano have succeeded so well on Earth because they create their own food, using a power source that is ubiquitous and sustainable. It’s such a good strategy that other life-forms learned from cyano’s success millions of years ago and absorbed these tiny engines into their own fuel-production processes. Humans may not be able to merge with cyano on a biological level—at least, not with current levels of technology—but many scientists are working on ways we could use photosynthesis to create more sustainable energy sources to help humans survive as a mass society.
One of these scientists is physicist-turned-biologist Himadri Pakrasi, who runs Washington University’s International Center for Advanced Renewable Energy and Sustainability (I-CARES). With a thatch of curly black hair just beginning to turn gray and a ready smile, Pakrasi radiates enthusiasm for his work. The first time I spoke to him, by phone, it was to find out how his lab had managed to create energy using water, light, and bacteria. “You should come out here and see!” he exclaimed. Very few scientists would invite a writer they’d never met before to visit their labs, but Pakrasi is the kind of guy who wants to get people engaged with his work—even strangers from halfway across the country. It was easy for me to understand how he’d built up a large international group of collaborators at Washington University, including scientists, city planners, and engineers.
When I arrived in St. Louis a couple of months later, Pakrasi told me that he’d been fascinated by photosynthesis his whole life. “Every plant is a fantastic power reactor,” he explained. “Let’s learn from nature how to do that ourselves. Let’s have a perpetual synthetic plant that makes energy.” He and his colleagues at I-CARES are convinced humans could be using algae to fuel our cities in a century. The cornfields outside Pakrasi’s office window would bloom with photosynthetic antennae, or superefficient solar cells atop flexible structures, their light-consuming faces twisting to follow the path of the sun across the sky. Energy breweries the size of local beer megacorp Anheuser-Busch would be packed with vats full of bubbling blue-green algae that could be used in batteries or other chemical processes. Humanity would survive the fossil-fuel age by drawing energy from cyano. But before Pakrasi’s visions can come to pass, scientists need to figure out how photosynthesis works.
In his lab at Washington University in St. Louis, researcher Himadri Pakrasi shows another researcher some of the cyanobacteria colonies that have been engineered to produce higher amounts of hydrogen. (illustration credit ill.8)
Despite what you may have learned in high school biology, photosynthesis isn’t simple. In fact, it’s a chemical process that follows some seriously weird and mysterious pathways—some of which we still don’t understand. Another Washington University professor, the physicist Cynthia Lo, flipped her laptop open to show me her work on photosynthesis, glanced at some diagrams, and looked momentarily exasperated. “You know why most plants are green?” she asked rhetorically. “It’s because they’re terrible at capturing and absorbing green light. So they capture blue light, but they reflect green. And that’s what you’re seeing in this bright green algae.” Lo is one of Pakrasi’s research collaborators at I-CARES, and the principal investigator on the Photosynthetic Antenna Project. She’s working out the basic science that might one day lead to Pakrasi’s vision of superefficient solar cells collecting light to power the city of St. Louis. Lo clicked through some diagrams of how photosynthesis works at the atomic level, photons colliding with molecules called pigments to produce energy.
Then Lo returned to a theme that would come up a lot in our conversation: cyano are actually terrible at reaping the benefits of photosynthesis. Not only are they missing out on green light, but they only convert about 3 percent of the light they harvest into energy. By comparison, commercially available solar cells convert about 10 to 20 percent of incoming light into electricity. But, Lo said, today’s solar cells can only harvest a small percentage of the light wavelengths that cyano collect—so the bacteria are still way ahead of us in that department. But not for long, if Lo and her lab have anything to say about it.
Lo’s research into the physics behind light capture could help engineers build solar cells that replicate the molecular smashup we see during photosynthesis. Engineers call this biomimesis, or the practice of imitating biological forms to make artificial systems work as efficiently as living systems do—or more efficiently. “A biological system is intriguing because nature has optimized it,” Lo explained. But it’s not optimized enough. Algae harvests light really efficiently, but doesn’t convert it into energy efficiently. Solar cells are efficient at making energy but not at light harvesting. Ultimately, Lo’s goal is to figure out what it would take to develop what she calls a biohybrid solar cell that combines the light-capturing abilities of cyano with the energy-conversion abilities of existing solar-energy technology.
By trying to copy the energy reactors inside each cyano cell, Lo and her team are learning the best possible lesson they can from this mega survivor. They are trying to diversify our energy supply, creating new ways for us to gain energy from the environment so that we can survive long-term with a sustainable electrical grid. It may be decades before we crack the code on photosynthesis, but this ancient organism could guarantee a better future for the planet—just the way it did billions of years ago.
Another of Pakrasi’s collaborators is working on a strategy to take us from a world run by coal to one powered by plants. Environmental engineer Richard Axelbaum, a wiry man whose office desk is decorated with angular chunks of coal, is interested in the near future of alternative energy. Pakrasi and Lo are looking perhaps half a century ahead, while Axelbaum looks just 10 to 20 years out. He has to be a pragmatist. That’s why he works on “cleaner coal” technology and carbon sequestration, the practice of sustainably disposing of coal’s greenhouse gas by-products.
One of his projects is a prototype coal-combustion facility called the Advanced Coal and Energy Research Facility, located in a huge, high-ceilinged warehouse on the Washington University campus. The facility sustains tanks of healthy algae using a by-product of coal processing. From a viewing gallery two floors above, Axelbaum showed me a tangle of thick pipes, cylindrical tanks, and a grid of shelves packed full of bubbling aquariums. Axelbaum pointed to a tank that looks like an outsized metal barrel turned on its side. “That’s the coal-combustion chamber,” he explained. Unlike typical coal-burning plants, this chamber burns the coal in a pure oxygen environment. As a result, the only by-products of the process are “cleaner” because they’re composed almost entirely of carbon dioxide and ash, with no nitrogen compounds mixed in. “Every generation has had its clean coal,” Axelbaum remarked. Early twentieth-century facilities improved on the extremely dirty coal-burning practices of the nineteenth century, for example. And now he’s hoping that we can improve the process even more, bringing us one step closer to truly clean energy.
Axelbaum’s finger followed a thick duct emerging from the combustion chamber. “That goes to a white-ash capture chamber,” he said, identifying a big, rectangular bin. Normally, coal ash is stored in large open-air ponds, which can cause environmental damage. “Our hope is that all this ash can be put to use, whether in concrete or new kinds of conductive materials,” Axelbaum said. As for the carbon dioxide? “That’s going over to the algae tanks.” Axelbaum pointed at pipes leading to the aquariums. The algae absorb the carbon, thriving on the gas. Axelbaum’s oxy-coal combustion could be feeding (literally) the next generation of superclean energy production.
A couple of years before I visited Pakrasi, his team made an incredible breakthrough. They were working with a mutant strain of cyano that releases hydrogen instead of oxygen during photosynthesis, and they managed to coax the algae to produce ten times more hydrogen than other strains had. Hydrogen is often called a clean fuel because when it’s burned it releases mostly water. Hydrogen fuel has been used for rockets, but its production is too expensive for consumer markets. Still, its widespread use in every home is part of the future of cyano-powered energy that Pakrasi, Lo, and Axelbaum dream about.
Imagine a world where brewers grow hydrogen fuel by feeding cyano with the carbon dioxide released from burning coal. The Pakrasi lab’s cyano also consumes glycogen, a by-product of biodiesel production. So basically, these algae cells are eating two harmful by-products of energy production to produce a form of fuel whose consumption releases almost no toxins at all. “They give you a lot of bang for your buck,” Pakrasi said with a laugh. Eventually, we could wean ourselves off coal and make the leap into a cyano-powered world full of new kinds of green fuel.
Pakrasi imagines a future where biologists could even develop specific strains of cyano to transform all aspects of industrial production. The bacteria could eventually replace petroleum, and aid in the production of chemicals like polypropylene, which is used in the synthesis of everything from rope and lab equipment to thermal underwear and durable plastic-food containers. Famed scientist and U.S. secretary of energy Steven Chu has talked about replacing the oil economy with a biofuel “glucose economy.” But Pakrasi and his colleagues in I-CARES have refined this notion even further, and speculate about a global algae economy whose engines run on photosynthesis.
Pakrasi, who studied physics in India before coming to the States for his Ph.D. in biology, says he often looks to India and China for inspiration when he thinks about how to implement the discoveries he’s making in the lab. “It’s hard to [test new energy systems] here or in Europe because these countries have stable infrastructures that are already built. We’re always trying to catch up, to retrofit,” he mused. “But in China or India, it seems like every millisecond they are setting up new structures. These are the places where the technology we’re developing here can be applied directly.” Under Pakrasi’s guidance, I-CARES has developed strong relationships with universities in India and China, and researchers in St. Louis collaborate with colleagues across the world. They’re even reaching out beyond the sciences, to bring in experts in ethics and sociology. “As scientists, we’re good at coming up with technical solutions,” Pakrasi said, “but as far as the policy and human angles, we have to collaborate with [other branches of the university too.]”
I-CARES is the kind of institution that we’ll be seeing more often at universities and in industry, combining people from many disciplines to come up with global solutions to problems that straddle the line between science and society. Already, the U.S. Department of Energy has funded a massive effort in California, the Joint Center for Artificial Photosynthesis, whose aims are similar to I-CARES. Its team of over a hundred scientists, many based at Caltech and the Lawrence Berkeley National Laboratory, aims to develop a way to extract clean energy from sunlight, water, and carbon, just the way plants do.
This futuristic collaborative research could one day save the world. And it grew out of the simple cyanobacteria and its best lesson, which is to adapt and diversify by taking advantage of a sustainable form of energy. In the next chapter, we’ll learn about another life-form with an extraordinary survival mechanism—one that may have helped bring it back from the brink of extinction. You might say that this animal, the gray whale, lives by memory alone.