After Geoengineering

by Holly Jean Buck

  Wilcox’s concept was to grow the giant kelp Macrocystis in the surface waters of the open ocean. Because most of these surface waters are a desert, nutrient wise, he proposed to pump water up from the nutrient-rich waters that lie about 300 meters below. But building the structures on which kelp would grow, as well as the mechanisms for pumping water up, presented immense engineering challenges. What’s more, storms and biological organisms plague human efforts to cultivate this fluid terrain. How could the kelp be held together in a farm unit without being lost to tides and currents? To solve these problems, Wilcox imagined free-floating farms that would use propulsion systems to keep them circulating around the ocean’s massive eddy patterns.

  The scale was also a problem: to make fuel out of kelp, you need a lot of it. Dr. Wilcox’s calculations indicated that the farms would have to stretch 100,000 acres or more to be a cost-competitive source of energy. Moreover, at the end of the 1970s, the gas sector was deregulated, and oil embargoes ended. And by 1982, the funders were no longer interested.

  However, there has been remarkable progress in engineering in marine environments, and technology more broadly, since the 1970s. Could advances in robotics help kelp farms scale?

  The startup Marine BioEnergy could be seen in some sense as a descendant of OFEF, as it was founded by the son of Dr. Howard Wilcox, Brian Wilcox, and his wife, Cindy. Marine BioEnergy is investigating cultivation of long-line kelp in robotic farms—work that has attracted press interest from the likes of Fast Company, National Public Radio, and the New York Times.

  The new kelp farm concept is simple: the entire kelp farm gets moved down at night to receive nutrients from deeper waters, and up during the day to reach sunlight. This is a significant difference with the 1970s concept: submerging the kelp rather than building a large pumping infrastructure saves a lot of money because it means the farms can be smaller. Drone submarines would tow these kelp farms to new waters, communicating with harvesters by satellite, which would save labor costs. The drones could also submerge the farms to avoid big storms and passing ships. It’s an ambitious but well thought-out project, involving many collaborators and supported by ARPA-E.

  The first step for the Marine BioEnergy consortium is to figure out the mechanics of kelp farming. As Cindy Wilcox told me, “Right now the biology question is the dominant question: Does a fast-growing kelp thrive when submerged to depth to absorb nutrients and surfaced during the day to absorb sunlight?” Marine BioEnergy is working with marine biologists and scientific divers at the University of Southern California to better understand this piece of the puzzle. The various species will be tested on an anchored research buoy—also known as “the kelp elevator”—near Catalina Island. The buoy has a boom that is surfaced during the day and submerged at night to find out which species thrive in this environment. The target kelp, Macrocystis, grows a foot a day with adequate nutrients. Moreover, some of these kelp plants have been found to grow up to three times faster than their neighbors, implying that there is much more to learn about why some plants are more productive (something other researchers like Dr. Yarish are also working on).

  The second step is to harvest the kelp and make a biocrude out of it. Researchers at Pacific Northwest National Labs have devised a process to convert kelp into biocrude (a hydrothermal liquefaction and catalytic hydrothermal gasification process) that takes about an hour in a reactor and doesn’t require fermentation; in theory, methane output from the process itself could be used as power source. Then, an open question is whether it makes more sense to bring the harvested kelp back to land to process it, or instead to process it on the open ocean and have tankers come and fill up out there. Marine BioEnergy’s latest idea is to rendezvous the drones with the harvesters four times a year. The technology for all of this exists, but it needs to be integrated for this new application, Cindy Wilcox told me. “Right now we are working to determine the most cost-effective methods to implement the subsystems and get the end-to-end process underway.”

  The fuel could also complement renewables, supplying both liquid fuels and methane: as Cindy Wilcox suggests, on days without wind or sun to power the grid, carbon-neutral methane could fuel the turbines. “We don’t expect batteries or pumped hydropower to provide adequate storage on the scale needed at a cost-competitive price. Kelp-based methane pumped through the current pipelines will meet the need and stabilize the grid,” she explains.

  From ocean farming to carbon removal

  The idea of cultivating seaweed went under the radar between the 1970s and today, but it didn’t disappear. During the 1990s, there were several workshops held on the marine biomass concept—and they were specifically focused on climate mitigation. More recently, an interdisciplinary team has proposed a method for using seaweed not only to mitigate climate change but also to achieve negative emissions. Described as “ocean afforestation,” the concept, outlined by marine botanist Antoine de Ramon N’Yeurt and colleagues in a 2012 paper, entails several steps: growing and harvesting the seaweed, digesting it as biomethane, extracting the separated carbon dioxide and methane, recycling the nutrients, and permanently storing the carbon dioxide via some geophysical or geochemical technology. (One idea is to store the carbon as liquid with seawater, inside a geosynthetic membrane tube resting on the seafloor.) They calculate that afforesting 9 percent of the world’s ocean surface could be sufficient to replace fossil fuel energy, remove 53 billion tons of carbon dioxide, and increase sustainable fish production.8 Some of the people involved with these initial calculators are continuing their work within a network called the Ocean Foresters.

  Ocean afforestation sounds grandiose—but that may be because we don’t have institutions that work on this kind of ecosystem-scale research and development. Most innovation is undertaken by narrow specialists pursuing particular niche products, whereas this idea evolved from a whole host of people, including a former wastewater engineer and a marine botanist from Fiji. Indeed, the authors note, it would be like putting a man on the moon, though likely a much better return on investment; it also involves low-tech components that could scale quickly. The Ocean Foresters have evolved their concepts in the years after the publication of this paper, and their ecosystem-level proposal has captured the imagination of popular science writing—including in the essay collection Drawdown (2017), or Australian author Tim Flannery’s Atmosphere of Hope: Searching for Solutions to the Climate Crisis (2015). Mark Capron of the Ocean Foresters points out that it’s not a pure carbon removal technology; rather, seaweed cultivation is best viewed as holistic mitigation and adaptation. Nevertheless, there has been little actual momentum to pursue these types of multi-step, holistic solutions, which, in order to form even demonstration projects, require coordination of multiple scientific and engineering fields as well as among ocean users.

  Industrial or boutique production?

  Carbon removal at climate-significant scales with seaweed seems to imply industrial production: vast monocultures that can reap economies of scale. But many seaweed enthusiasts are interested in a different model, a polycultural approach to marine agronomy called integrated multi-trophic aquaculture (IMTA). It can be thought of as a counterpart to some of the agroecological practices on land, in which by-products from one species are recycled to become inputs for another. There are plenty of traditional models. For instance, in carp polyculture in China, mulberry was cultivated using nutrient-rich pond sediments, the leaves were fed to silkworms, and waste from silk production and processing was returned to fishponds stocked with Chinese carp.9 And today, in Sungo Bay in the Shandong Peninsula in Northern China, there’s a system where abalone feed on kelp, and their waste is then used by sea cucumbers; in turn, the kelp assimilate the waste produced by both the abalone and sea cucumbers.10

  A small but dedicated community of academics, entrepreneurs, and NGOs is advocating for this type of aquaculture. In the United States, from Connecticut to Maine to Alaska to California, cottage cultivators are experimenting
with how to set up a seaweed industry compatible with sustainability and social justice principles. One oft-profiled organization, GreenWave, advocates for “3-D ocean farming,” where kelp-and-shellfish farms make use of the whole water column. It isn’t an easy task: How can you stand up a seaweed industry according to social justice and sustainability principles, when industrial production elsewhere is so much cheaper? People in Europe are thinking about this as well: for example, colocation of seaweed production and wind farms in the North Sea (though one study found this totally uneconomical, as the seaweed would face heavy competition from Chinese production).11 Dr. Yarish explains, “We can’t employ technologies that you see in Asia, where labor costs are very low; we have to adapt.” This means using techniques that require not ten people but one or two. Part of his approach to helping the industry get on its feet is to make all his work open source. “I made a decision a number of years ago that in order to develop a seaweed cultivation industry in North America—the biggest problem had been people trying to always do things quietly. Secretly … And I felt that at least the primary research should be open source, so people would not have that as a limitation.” Yarish’s team has a free handbook for cultivating seaweed, as well as a great six-part introduction on YouTube. But another fundamental challenge is that in Western cultures, there is no culture of seaweed cultivation. So how does seaweed production start in a community? You want coastal communities to have a “fair return on their investment,” Yarish explains, in terms of their labor, their energies, their nurturing of the farm system. If outsiders come in and start showing people how to grow seaweed, or begin investing the capital, it might not flow back to those communities. At the same time, to quickly scale up a seaweed industry that could support big goals like marine biomass for carbon removal, there would have to be some diffusion of knowledge or technology. In the absence of strong government intervention, the seascape favors big companies—or otherwise, requires a coordinated, collective effort by farmers working together, the beginnings of which we can see in places like Connecticut.

  Seaweed cultivation can come with environmental co-benefits, such as reducing commercial fishing activity and allowing fish stocks to recover.12 In China, seaweed aquaculture is already of such a scale “that it may be of regional biogeochemical significance”—for instance, it’s playing a pivotal role in addressing the problem of coastal eutrophication, according to a paper in Scientific Reports. Scientists Xi Xiao and colleagues found that the seaweed industry is already removing 75,000 tons of nitrogen and 9,500 tons of phosphorus from coastal waters each year. Just 1.5 times more seaweed cultivation would be able to remove all the phosphorus flowing into the seas,13 though it would be hard to take up all the nitrogen. Capturing these co-benefits will to some extent rely on good system design. For the time being, seaweed cultivation, because it is a new industry—for the West, anyway—is mostly unregulated.

  If you’ve never thought about seaweed regulation—I hadn’t, before writing this book—you might be mystified: Why would seaweed need regulation? But there are matters like the spread of invasive species, or diseases. For example, a bacterial disease called ice-ice infects a red seaweed called Kappaphycus, turning its branches into ghastly white icicles. During the past 10–15 years, the disease caused millions in crop losses in the Phillippines and Indonesia, before it spread to farms in Tanzania and Mozambique in the Indian ocean.14 There’s also regulation to help consumers. In general, people eating seaweed might want it to be traceable and clean, reputably sourced. Policy aimed at seaweed could also aid farmers by helping them cope both with low prices (most of the value is added in processing rather than in growing), and with the impact of climate change (since seaweed farming is vulnerable to increasing storm activity). State-subsidized aquaculture insurance, such as in Korea, could also support farmers. Another regulatory challenge will be to figure out how to incorporate seaweed farming as carbon removal into climate policy, at both national and international scales. For now, it’s tough for seaweeds to qualify as carbon sinks under the UN Framework Convention on Climate Change. The definition has been set up for trees—in terms of carbon turnover time—but with seaweeds, the carbon they draw down is easily decomposed and released again, and the turnover time is less than ten years (versus several decades for trees), excluding for the detritus that goes into the depths.15 Of course, there are a variety of ideas about how to sequester the biomass—sinking it into the deep sea, into submarine canyons, and so forth, which researchers have termed “seaweed carbon capture and sink,” or “seaweed CCS.”16

  Despite all the challenges, the dream of multifunctional seascapes near coastal communities holds powerful promise. The Ocean Foresters’ vision includes construction of restorative coastal infrastructure, enhancement of biological infrastructure like mangroves and dunes, and use of tensile fabric to make flexible breakwaters. The automated offshore production would be stewarded by human attendants: the submarine and the aerial drone enable “boutique forest management,” generating a decent living for the people taking care of the machines.17 Other designs involve the use of offshore wind turbines to anchor seaweed cultivation. The production of sustainable biofuels would also help meet the energy needs of island and rural coastal communities. This all might sound futuristic, but the future is rapidly crashing down on us. In short, if we are to avoid repeating agriculture’s grave mistakes of the past in fluid territory, now is the time to advocate for sustainable worker and community-oriented models of marine crop production.

  From the perspective of researchers experimenting with seaweed for carbon removal, there are two looming risks—on top of the more basic risk of economic unfeasibility, namely, that the policy and public interest needed to support and nurture it fails to grow. The first risk is climate change. All over the world, for example, warming sea temperatures are decimating natural kelp forests. One scientific report graphically describes the “urchin barrens” that are settling in where kelp forest used to be—these warm-water species mow down everything in their path. Apparently, they are “almost immune to starvation,” living for over five decades. And when they get hungry, they destroy more: their jaws and teeth actually enlarge when they are experiencing severe hunger. The report offers more grisly details: when stressed, they form fronts that march across the seafloor, hunting for food.18 And the voracious urchins are just one instance among the many ways that climate change makes all kinds of agriculture trickier.

  The second risk for people working on seaweed is that some other innovation comes along and makes the first technology obsolete. We often think of carbon removal, and decarbonization more generally, as a portfolio or series of wedges, each of which will be necessary and appropriate in a particular social context. In reality, however, some technologies come at the expense of others. It’s quite possible that some of the geologic or chemical techniques for removing and storing carbon would be more attractive to current actor-interest groups than the natural and cultivation-based techniques described in this section. This is something the farmers and cultivators of the world may not be so thrilled to contemplate. Even so, seaweed biofuels potentially offer a transformative fuel source, and it’s worth thinking about how the industry might look at the end of the century.

  Sketch: Ghost Bar

  A sign at the horizon read Ghost Bar. The blue neon bobbed on the dark water.

  On-screen, a clump of glowing green showed seaweed waiting to be harvested, and two red lights signaled farms in need of attention. A barnacle in the gears, maybe. Have you tried turning it off and on again?

  Someone else could have that gig. She didn’t need to be top of the repair charts, just to make enough that she could save a little. She wanted to stop.

  She’d been on the boat a week. She frowned at the mirror, rubbed citrus oil into her skin, tied back her hair as she drew close. The geopolymer base floated on fiberglass tubes. Nestled between the bar and the barkeeper’s quarters was a tiny greenhouse and a chicken coop. She
tied up among the boats docked at the platform edge.

  A blast of ocean air followed her through the heavy door. There was no one behind the bar. She held her breath. And then the bartender stood from below the bar and saw her, and smiled. She smiled too.

  “How are you doing, Vilma?” he asked.

  “Another day in paradise,” she said. She pulled up a stool.

  One wall was all window. She saw a palm tree swaying in its bolted bucket. The sky was streaked with magenta and violet clouds.

  “Usual?”

  “Surprise me.”

  He went into the back. A black cat wound its way around her feet. The bartender returned with sliced tomato and a fried egg on hot flatbread. “Fresh,” he said. “The egg.”

  “Awesome.”

  He poured her a generous glass of gin, twisting a banana leaf into an umbrella.

  “This is gorgeous,” she said, admiring the food. He poured himself a whiskey. They touched glasses.

  She couldn’t think what to say. After her last breakup, she’d wanted solitude, to work on her music. Hence the marine systems repair course, hence the boat: the only solitary place in the world was the open ocean. But there’d been months of it now, and she had six compositions, none of which she was quite content with.

  He told her stories: about his customers, about the chaotic week when the real-time translator had broken down. She asked after the health of the chicken. The biocrude heater came on. Someone put nueva-bhangra on the virtual jukebox. The lights auto-adjusted to warm tones.