Going Carbon-Neutral With Miscanthus

So how does a Canadian succeed? Dean slides open a greenhouse door to show me. Forget tomato bushes. I am looking into an eight-foot- tall solid wall of tomato vines that extends the sixty-foot length of the greenhouse. It is densely hung with tomatoes, the largest, reddest ones toward the bottom, little green ones at the top. I peer through the wall, and see another one just a few feet behind this one. Dean tells me there are about a hundred tomato walls—he calls them rows, but that doesn’t do justice to their bulk—in each greenhouse. This is tomato growing at its most intensive and efficient.

We look at the base of one wall. Forget soil. Two tomato vines, thick as ropes, emerge every foot or so from a foam block set in a narrow trough in the concrete floor. A black umbilical cord of water and nutrients runs into each block. Far above, a horizontal wire runs the length of the greenhouse just below the ridgeline. Spools of string hang down from the wire every few feet. Each vine is assigned its own string and has been trained to grow up along it. Every two weeks, the spools move farther along the horizontal wire and unwind about two feet of string. Every week, a worker on a lift twirls a newly grown length of vine up the bare string toward the overhead wire. The tip of each vine grows farther and farther from its base. Eventually the tips will be sixty feet from their roots. The lengthening of the strings effectively lowers the older portions of the vines, so that great ropes of parallel, leafy, tomato-filled vines slope very gradually from floor to ceiling.

At the top of the vines, new leaves and a cluster of little yellow flowers emerge. I run my eyes down a vine and count eight clusters of tomatoes. The tomatoes in the topmost cluster are small and green, and each successively lower group is in a greater state of ripeness. By the time the tomatoes are perfectly ripe and bulging, they’re about knee height. The low drone I hear in the greenhouse comes from air circulation fans, but it could be the thrum of tomatoes growing at full throttle. Every leaf in here is green and healthy; every fruit is blemish-free.

Dean tells me he can now grow as many pounds of tomatoes in one acre indoors as his Mexican counterparts can grow outdoors in forty-seven. In the last ten years, he has tripled production per acre, thanks to improvements in greenhouse technology and the breeding process. He also has refined his crop selection, choosing to grow only specialty tomatoes—including twenty-six varieties of heirlooms—that have higher profit margins. The only variable he can’t improve is the Canadian climate and his concomitant need for fuel. About 40 percent of his cost of production is energy, and he feels the pain of every penny increase. More than any other worry—competition, blight and bugs, labor costs—it is the volatility of energy prices that keeps him up at night.

“My father burned coal to heat the greenhouses until 1967,” Dean tells me. “Then oil refining became a business in the Port Huron area, and he burned ‘bunker oil,’ the thick oil left at the end of the refining process. By the time I got involved in the business, the infrastructure for natural gas had arrived, and I kept switching between gas and coal, going back to coal when it was cheap. Then, in 2002, all fuels skyrocketed. Our heating costs went from thirty thousand dollars an acre to one hundred thousand dollars in one season.

“The situation was dire, and I looked around for any alternative, and ended up moving into wood. There’s no forest around here, but I found construction debris that otherwise would have ended up in a landfill. Every time I saw someone tearing down a building, I was there asking if I could haul away the lumber. For a while, it was fantastic: I saw my energy costs drop to twenty thousand dollars an acre. But soon everyone was going after the stuff, and builders stopped giving it away. It became a commodity. Then it got scarce, and the price went way up. Fortunately, by that time coal had become cheap again. Right now I’m burning natural gas.”

About five years ago, Dean explains, his inability to get “a line of sight” on future fuel costs and his experience burning lumber inspired him to look into biomass for energy. If he could grow his own fuel, he might fix his long-term energy costs and sleep better. Maybe, with fixed energy costs, he could offer longer-term sales contracts for his tomatoes, which would attract buyers. And he figured that if a cap-and-trade system for carbon emissions ever develops, as it has for sulfur emissions, he could sell his carbon credits.

Miscanthus giganteus

In 2006 he took a tour of European biomass farms. The English and the Germans had more varied experience with growing biomass than North Americans, who were focused on fermenting corn into ethanol to supplement gasoline. He stopped in on farmers cultivating willows and poplars, Japanese knotweed, switchgrass, and miscanthus. Knotweed turned out to be an invasive species in the United States, and therefore a nonstarter. Willows and poplars, while fast growing for trees, nonetheless take thirty years to get to harvest. In the interim, the crop could be devastated by disease, insects, or fire. Switchgrass, a perennial grass native to the North American plains, was an interesting possibility. But even more attractive was miscanthus, a perennial grass native to Asia and Africa. In Germany, researchers were having success with a hybrid called Miscanthus giganteus, a variety that grows as tall as twelve feet, and produces at least twice as much biomass per acre as switchgrass.

In Dean’s eyes, the crop had additional attractions. Not only is it a perennial; it has proved to be particularly persistent. He saw experimental plots in Germany that had been growing for two decades. In Japan, where miscanthus has been cultivated for centuries as roof thatch, some stands are two hundred years old. Because giganteus is a sterile hybrid, it couldn’t go to seed and escape his farm and invade his neighbors’ fields. Nor would it, like kudzu, colonize by creeping: After twenty years, Danish experimental stands have expanded by only a few feet. If the crop didn’t work out, it would be easy to uproot. Pests have no interest in its tough leaves, and after the first year, it grows so tall so quickly, it shades out its weedy competitors. Miscanthus can remain in the field, straw-colored and sere, until late fall or even spring, when idle harvesting and baling machines can take it down. The longer it stands in cold weather, the drier—and the better for burning—it gets. Bales of miscanthus can be left in the field for months without degrading, so there would be no storage costs.

Unlike the corn grown for ethanol in North America, miscanthus grows well on marginal land too steep, too sandy, or too low in fertility to grow row crops. In the late fall, as it stops photosynthesizing, it sends the nutrients in its stalks and leaves back underground, which means a field of miscanthus needs few or no costly fertilizers. And giganteus is unpatented and freely available. The only downside seemed to be that no one had yet figured out how to plant it efficiently, so initial planting costs would be high, but Dean figured he could overcome this. On his return from Europe, Stephen Long, professor at the University of Illinois and one of the world’s leading miscanthus researchers, gave him five rhizomes to try in Ontario.

Dean takes me outside to see one of the miscanthus fields descended from those rhizomes. From a distance, the field reminds me of the blocky mesas that rise abruptly out of the landscape in the American Southwest, except, instead of ochers and beiges, here the hues are emerald and dark green. As we approach, the mesa reveals itself to be a dense mass of vertical canes well clothed in bladelike leaves. The whole assemblage sways and shivers in the morning’s brisk breeze. Dean urges me to stay back a minute to take a photograph, and he strides ahead to position himself at the front edge of the field. With Dean in the photo, it is clear that the plants are already nearly twice his six-foot height, and it is only mid-July. Giganteus, indeed.

When Dean and I stand at the edge of the field to look more closely at the plants, I can see that the leaves, dark green with a thin, white stripe down the midline, emerge at every joint of a segmented cane. With two hands, Dean grabs a cane near its base and, tugging hard, pulls it out of the ground, along with its subterranean anchor. He is careful not to grab the leaves, which are covered in microscopic silica, a deterrent to insects and small herbivores. (He recently got in trouble with his wife, he tells me sheepishly, for letting their two youngest sons play hide-and- seek in a miscanthus field. When his wife put the boys in a bath with Epsom salts that evening, they shrieked with the sting from invisible cuts.)

He snaps off the cane and hands me what looks like a piece of thick, gnarly root about eight inches long. It’s not really a root, he explains, but a rhizome, a stem that grows horizontally underground. The rhizome is segmented, and each segment or node has a large and stubby bud. The buds are capable of producing either a new rhizome, a fibrous root, or a new cane, depending on the hormonal signal they receive. Over time, many of the buds will become new canes.

Although it is the tough canes that are harvested for biofuel, it is miscanthus’s leaves that are key to its success. Grasses are newcomers to the planet’s flora, coming on the scene just as the dinosaurs vanished 65 million years ago at the end of the Cretaceous. No one knows for sure why they evolved so late in the geologic day, but climate change likely played a role. At the time, the higher latitudes in the continents’ interiors were becoming more arid and fires more frequent. Grasses are well adapted to fire because their growing tips are at or even below ground level where, sheltered from flames, they can regenerate that very season. Trees, on the other hand, are either killed outright or take years to recover.

The evolution of large mammals in the post-Cretaceous era also helped the grasses evolve. By 55 million years ago, grazing hoofed animals, the ancestors of modern horses, antelopes, cattle, and camels, were clipping the tender tips of shrubby plants and small trees, stunting or killing them and opening more territory for grasses. Grazing animals might munch grasses to the ground, but when the herd moved on, the grasses sprang up again. By ten million years ago, temperate regions were covered in vast grasslands much like the modern prairies of North America, steppes of Eurasia, pampas of South America, and veldt of southern Africa.

About that time, in hotter, drier environments closer to the equator, a new class of grasses, what you might call supergrasses, proliferated. These species are today’s critical food crops of sugarcane, corn, millet, and sorghum, as well as bamboo and (ta-da!) miscanthus. The key to their success was their reinvention of photosynthesis.

Most plants and the older grasses photosynthesize in a “C3” fashion, and as successful as they were and are, they have a physiological weakness. One of the steps in fixing atmospheric carbon dioxide into sugars involves the enzyme RuBisCO. But, RuBisCO regularly makes a mistake and fixes oxygen instead of carbon dioxide. The plant then needs to shed that oxygen, and in doing so, loses some carbon it recently trapped. In hot weather, the problem gets worse.

When plants need to conserve water—that is, when they are losing more water through evaporation from their leaves than their roots can replace—their stomata automatically close. When the stomata close, waste oxygen can’t escape and accumulates—and is fixed by RuBisCO—in the leaves. In hot conditions, C3 plants make fewer sugars.

Certain grasses in the tropics evolved a couple of anatomical and physiological tricks that allowed them to get around this inefficiency. These “C4” plants developed a new biochemical pathway (only discovered by scientists in 1966) that starts by putting carbon into a four-carbon, instead of a three-carbon, compound (hence “C4” and “C3”). That compound is pumped into bundle-sheath cells, the cells that surround leaf veins. In C4 plants, the bundle-sheath cells themselves photosynthesize, while in C3 plants they typically do not. More important, in the C4s these cells are able to concentrate carbon dioxide at a higher level than is in the atmosphere. RuBisCO therefore contacts and interacts with more carbon dioxide molecules than it otherwise would, so more sugars are created. Because the bundle-sheath cells are impermeable to oxygen, less wasteful oxygen fixation occurs.

In sum, C4 plants learned how to make more hay—about 40 percent more—while the sun shines. That is why although they represent only 1 percent of the world’s plant species, they represent 20 percent of the Earth’s vegetation coverage and produce about 30 percent of terrestrial carbon. That is also why fourteen out of the eighteen of the world’s worst weeds (we’re looking at you, crabgrass and pigweed) are C4 species. And that is why miscanthus is a prime candidate for making biofuel. Moreover, it turns out that among C4s, miscanthus is especially good at accumulating carbon, even in a climate as untropical as Ontario. In the spring, miscanthus sends up new shoots from its rhizomes several weeks earlier than corn, which has to develop from seed, and even switchgrass. Its leaves continue to photosynthesize weeks after those two have called it a season. I am not surprised to learn, looking at the impenetrable mass of leaves in front of me, that miscanthus has more leaves with a larger collective surface than other C4s.

By the spring of 2008, using a combination of microscopic tissue culture and by manually dividing and redividing rhizomes, Dean turned Dr. Long’s five rhizomes into thousands, and planted them on sixty acres. By the end of one growing season Dean had ten times the number of plants that the university had. By 2014, Dean expects his tomato farm will be energy self-sufficient.

The psychological benefits of energy independence are considerable, but does growing miscanthus make business sense? Dean has four hundred marginally productive acres of his own in miscanthus, and he contracts with neighboring farmers to grow the rest. Dean figures that the cost of a gigajoule (a billion joules) of miscanthus-made energy is $4.20. Natural gas, which is cheap at the moment, costs about $6.50 per gigajoule. It doesn’t take a special furnace to burn the biofuel. At least on paper, miscanthus fuel is a winner.

The environment comes out ahead, too. Burning coal, natural gas, and oil that has been sequestered underground since the Carboniferous era releases climate-warming carbon dioxide into the atmosphere. While burning miscanthus in the winter adds carbon dioxide to the atmosphere, miscanthus took that carbon dioxide from the atmosphere in the spring and summer as it grew. The only fuel Dean uses in producing miscanthus energy is a little diesel for harvesting and baling the crop. In three years, he expects his farm will be nearly carbon neutral, which in a world where carbon dioxide levels are rising at an unprecedented rate is a significant accomplishment.

There are other environmental benefits, as well. Over the course of a summer, as the canes grow, the older, lower leaves fall off. They decay gradually, and will eventually return carbon and nutrients to the soil, but until then, the thick leaf litter provides good cover for small wildlife. The fallen leaves also slow evaporation from the soil. The underground portion of a miscanthus plant is equal in mass to the aboveground portion, which means it has a substantial impact on the subterranean ecology. The perennial roots of miscanthus reach deep into the ground, where they aerate the soil, leak nutrients to worms and insects, and add organic material to create a rich subterranean ecosystem. In terms of environmental impact, it is a crop much like perennial wheat, the holy grail of the Land Institute. Even better, it grows where no self-respecting wheat would grow.

Denmark, Spain, Italy, Hungary, France, and Germany have started multiple research and commercialization projects, and the European Union projects that 12 percent of its energy will come from miscanthus by 2050. In the United States, the USDA is supporting projects that are expected to have 100,000 acres in miscanthus. BP recently invested $500 million for miscanthus research at the University of Illinois.

I am fascinated by the prospect of new biofuels in general, and intrigued by miscanthus. When Dean tells me it would probably take about an acre and a half of miscanthus to heat a typical house in Ontario, I mentally add a good stand of miscanthus to my dream house, the one in the country where I won’t have to wonder whether a neighbor’s leylandii will fall on my roof. Miscanthus can’t fill all our energy needs. You can’t put miscanthus directly in your gas tank. But thanks to a million years of evolutionary fine-tuning, each leaf is a marvel of a machine for turning sunlight into stored energy.

This excerpt has been reprinted with permission fromA Garden of Marvels: How We Discovered That Flowers Have Sex, Leaves Eat Air, and Other Secrets of Plantsby Ruth Kassinger and published by William Morrow, 2014.