Drawing energy from algae farms is still costly, but can someday soon join a growing family of sustainable green biofuels.
Our newest sustainable and green biofuel may be right around the corner as we improve ways to draw energy from algae farms.
Photo courtesy Jurvetson
The available energy sources on our planet and beyond are staggering in potential, but as Powering the Future (Basic Books, 2011) explains, the market will only move to such sources once the prices drop. From the possibilities of drawing energy from algae farms to tapping the almost limitless bounty of solar energy, renewable energy waits only for humanity to find effective means of production. Nobel Prize Winner Robert B. Laughlin describes a world in which we’ve burned every drop of petroleum and consumed every bit of coal, yet still have methods of sustaining our ways of life. In this excerpt from the chapter “Calling All Cows,” Laughlin writes of the potential for farming energy from algae farms, and the hurdles we need to overcome before it is a sustainable alternative for green biofuels.
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The plants most likely to be exploited in the long term as an industrial carbon crop are saltwater microalgae. This prediction is somewhat of a stretch, because there is no saltwater agriculture industry at the moment from which you can make crop comparisons. However, microalgae grow, and thus fix carbon from the atmosphere, faster than any other plants in the world, so they’re very strong candidates. Their near-term production cost per unit mass is probably between five and ten times coal’s. This makes algae farms badly uncompetitive as an industrial carbon source while coal is plentiful but a potentially acceptable one when coal is exhausted. Other saltwater plants would have to beat this cost to win in the marketplace, and none of them can do so at the moment.
Microalgae also have an immense public relations advantage over other potential energy crops in that drawing energy from algae is quintessentially green. They’re not just natural things compatible with the environment; they’re the fundamental food source for the ocean’s entire ecosystem. These free-floating one-celled plants are visible at most ocean beaches as a green or greenish-blue tint of the light passing through the peaking surf. The powder blue color we find in open sea or in warm tropical waters indicates that the nutrients necessary for aggressive algae growth, chiefly nitrates and phosphates, are in short supply. But given a flow of nutrient-rich coastal runoff or a deep water upwelling, as we find on the Grand Banks of Newfoundland or Peru’s Humboldt Current, the water becomes turbid and green and abounds with life. Filter feeders such as shellfish, corals, and larval zooplankton eat the algae and multiply with abandon. Fish eat the filter feeders — and each other — eventually becoming abundant. Higher predators such as birds, seals, and killer whales eat the fish and likewise prosper. Commercial fishing operations thrive. The central role that algae may eventually play in the human economy when the coal runs out is thus extremely appealing, in that it echos the role they already play in the sea.
Farming algae is difficult, however... The fundamental reason why is that they achieve their great fecundity by avoiding responsibility, not by being gifted. A conventional food plant like corn has stems to erect, roots to put down, leaves to unfurl, seeds to generate, and so forth, not to mention longer-term things such as waiting for spring. But algae do none of these things. They lead a short, brutal life of freedom rather than a long one of endless toil, and they just don’t care about tomorrow. As a result, we have to do their chores for them if we want to raise them, and that costs money. The extra costs wind up being so great that no one can figure out how to farm algae profitably. That isn’t so surprising, for pure algal biomass is a green substitute for coal, a resource that is extremely cheap at the moment and correspondingly hard to beat. But the problem is worse than that, for algae become less productive than conventional agricultural plants, not more productive, once we discount the extra costs of raising them. Algae farming will probably not become a significant industry until both coal supplies and land resources for agriculture have run out.
Algae’s monumental cost problems make it almost impossible to take present-day algae biofuel companies seriously. We want to believe, but we find ourselves thinking instead about all those nutritious government subsidies. The most unforgettable of these subsidies is the high-priority U.S. congressional mandate that the Air Force secure a supply of green jet fuel at any price. Exactly how much the Air Force is paying isn’t public knowledge, but rumors are that it’s about ten times the cost of jet fuel made from petroleum. Not surprisingly, saltwater agriculture is a rather low priority with startups jockeying to supply this fuel, as is agriculture generally. For example, one of them is reported to be growing algae in plastic bags (made from petroleum) stacked in warehouses. Another isn’t engaging photosynthesis at all but is instead grazing its algae in the dark on cheap sugar, presumably obtained from conventional crops such as beets or cane. Another eschews growing algae completely and plans instead to harvest the fish that eat them, no doubt with the objective of grinding the fish up and processing the happy brew into gasoline and diesel fuel.
The absurdity of green biofuels that never see the sun is actually not funny, as it’s symptomatic of attempts to contravene the laws of economics — presumably out of fear of what those laws may portend. If the big energy companies won’t make algae biofuels, so the reasoning goes, we must do it for them, thus heading off impending catastrophe when the oil runs out. But there is no need at the moment to create saltwater agriculture that spares land and water for food production. If there were, we would have such agriculture. There also is no need to generate as much biomass as we possibly can as a carbon resource. The world is awash with cheap carbon fuels. The world also has agricultural land to spare. It pays farmers not to plant the fields they already have. It struggles to find buyers for subsidized butter and cheese in oversupply.
The energy industry’s sudden interest in algae might also be part of this absurdity, unfortunately. Green politics powerfully encourages “greenwash,” the practice of associating yourself with green causes to look more environmentally friendly than you actually are. Although the investments that the oil majors are presently making in algae look technically legitimate, they might just be public relations expenditures. We can’t tell, for the amounts of money involved, though considerable, are smaller than the potential costs of taxation, regulation, and political vexations that might be visited upon them for not being sufficiently green. Absent some truly unprecedented discovery or breakthrough, it will be hard not to smile knowingly whenever world-famous geneticists begin explaining their strategic algae oil partnerships that involve no farming until sometime way in the future, if ever.
Ironically, algae are easy to farm theoretically because all we need do is overfertilize them. This induces a population runaway called a bloom, a kind of plant version of a nuclear explosion. The growth rates we get are blistering — in some cases four times the seasonal average of the best corn fields. These artificial algae blooms emulate natural ones caused by nutrient upwellings in all the world’s oceans. Natural algae blooms are often hundreds of kilometers in size and can be seen from space by satellites. Rates of biomass creation in them can approach traditional food crop values, even though the blooms aren’t farmed. Some of this blooming is actually important for healthy ocean ecology. A well-known example is the spectacular phytoplankton bloom that occurs as pack ice retreats in the Antarctic spring. This algae bloom causes krill populations to explode, thereby enabling great blue whales and armies of penguins to stuff themselves in the southern oceans. Blooms can also be detrimental, as they are, for example, when noxious red tides sweep in from the oceans and poison clams. They also cause dead zones, such as the famous one just off the coast of Louisiana, where zealously producing algae die, sink to the bottom, use up all the oxygen by decaying, and thus kill the fish.
Algae’s practical biomass production rate is probably about twice corn’s. Nobody knows the precise number because commercial algae farms don’t yet exist, but this is a reasonable guess given what’s known. The twofold advantage only applies to warm, sunny climates, however, such as Hawaii or the deserts of Southern California. Algae farmed in places where there are seasons stop growing in the winter and thus produce, as a yearly average, roughly the amount of biomass corn does. Corn, it turns, out, has growth spurts too, and it’s a tough competitor. Assuming that the weather is warm, so that we can produce the energy from algae year round, the amount of pond area required to produce the energy equivalent of all the oil presently consumed in the United States is about twice the area presently planted in corn, or slightly more than the total area of Texas.
The long-term cost of transport fuel made from algae when the coal runs out is likely to be about twice the present cost of transport fuel made from petroleum, not ten times more, as present-day estimates suggest. The reason is simply that costs will lower over time in response to competitive pressures and improving economies of scale. The sole exception will be farming costs, which will then become the main price-determining factor, just as they are today in the food industry. The farmer’s cost to raise a given dry weight of biomass can be reasonably estimated at the cost of raising the same dry weight of corn silage. The cost of a given dry weight of corn silage, in turn, is about twice the present-day cost of the same weight of coal. But the price of coal is pegged to the price of conventional transport fuel through the implicit threat, if the latter stays high for too long, of competition from Fischer-Tropsch synthetic fuels. Thus the long-term cost of algae-based fuel probably cannot exceed the cost of Fischer-Tropsch fuel made from coal, pro-rated by the price difference between farmed corn and mined coal. That lies somewhere between two and three times present-day fuel prices, depending on the relative importance of the hydrogen and energy content of the biomass.
The industrial processes by which people convert this agricultural biomass into transport fuels (and carbon-based products generally) will probably be brute force gasification followed by catalytic synthesis. It’s conceivable that microbial processing will become cheaper than those methods and supplant them, thus reducing the amount of dirt and noise people have to put up with. But it’s a long shot because carbon, not energy, will be the expensive commodity by that time. To be competitive microbes would have to both maximally exploit carbon and make molecules suitable for trucks and cars. That’s a lot to ask of them.
Reprinted with permission from Powering the Future: How We Will (Eventually) Solve the Energy Crisis and Fuel the Civilization of Tomorrow by Robert B. Laughlin and published by Basic Books, 2011. Buy this book from our store: Powering the Future.
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