You Are Being Lied to About Dams

It’s a go. Brazilian President Luiz Inacio “Lula” da Silva just signed an agreement to build the Belo Monte dam on the Xingu River. It will be large: 3.75 miles of hulking concrete and 11,000 megawatts of power, enough energy to power 23 million homes. It will be the third-largest dam in the world, and is the very clear Brazilian answer to the question: Where will the 21st century’s energy come from? Dams are boasted as the best, cleanest, most sustainable response to that question, a far better option than decapitating the Appalachians, turning the Blue Ridge Mountains of West Virginia and the Cumberlands of Kentucky into wastelands.

Thus greenwashed, construction companies in the third world pour concrete as fast as they can mix it, while Clean Development Mechanism (CDM) credits pile up in the accounts of their governments. It makes for a neat-sounding plan: third world economic development gets powered by an infinitely renewable energy source, with salable credits from Western industrialized countries paying for the construction costs – clean capitalism for the planet. A neat plan, until you look a little closer, close enough to see the nitty-gritty substance. That’s where the trouble starts. Dams work by pushing pressurized water through turbines. That water spins them at enormous speed, creating energy. But how to pressurize the water? By building tremendous concrete barricades behind which it piles up in man-made lakes.

That’s where the trouble begins. Earthquake-inducing weaponry was long the province of science fiction writers, the object of Nikola Tesla’s feverish jottings about the “art of telegeodynamics.” Turns out it could be done, although not the way the more imaginative had envisioned. The sheer volume of water stored behind concrete dam walls can be so sizable as to actually cause seismic activity by affecting the stability of tectonic plates. Chinese scientists have implicated the Zipingpu Dam in the Sichuan earthquake of May 2008, in which perhaps 80,000 people died. Other scientists warn that the titanic Three Gorges Dam on the Yangtze could likewise cause tremors.

That would just be one more problem stemming from the Three Gorges project. That dam, audaciously immense, also required the relocation of rural and urban populations. Well before the project was complete, the government foresaw the forced migration of over 1.2 million people and the partial or total inundation of two cities, eleven countries, 140 towns, 326 townships and 1351 villagers, to create a bogglingly big reservoir – over 400 miles long. The reservoirs of such dams are breeding grounds for malaria mosquitoes and malaria prevalence in the regions ringing such reservoirs is far above the norm. The Chinese peasants who lived in the areas now flooded by Three Gorges’ reservoirs were pushed onto marginal or unfarmable land, effectively marginalizing them from meaningful economic activity.

In Brazil, meanwhile, over one million people have been displaced by the development of hydroelectric dams, with many human rights violations along the way. The Brazilian group MAB – Movement of those Affected by Dams or barragens, in Portuguese – contends that Brazilian hydroelectric power is another sop to industrial concerns, while the peasantry and indigenous groupings pay through massive spatial dislocation. Other beneficiaries include Western turbine manufacturers and joint Brazilian-Western industrial and raw materials processing enterprises that can make good use of cheap energy – cheap, because the price per megawatt doesn’t account for the ecological and human cost. Meanwhile, the middle and lower-middle classes, teetering perpetually on the brink of destitution, pay elevated rates as compared to the transnational conglomerates gorging on cheap energy.

But this isn’t some sort of not-in-my-backyard complaint. The carbon produced by fossil-fuel combustion goes into all of our backyards and hard decisions must be made: what to power, what to power it with, what will produce the least CO2 per unit of power? The surprising upshot is that even after deploying such relentlessly pragmatic measuring tools, dam construction may not be much good. Scientists working in Brazil have found that dams with wide, shallow reservoirs – particularly those in tropical biomes – may submerge so much forested or vegetation-covered territory that they may be net greenhouse gas emitters.

For example, the Balbina hydropower project in tropical Amazonas, one of Brazil’s northernmost states, submerged more than 2,600 square kilometers of forest for a small output of “clean” hydropower and a large output of greenhouse emissions. The emissions come not merely from the inevitable costs of building concrete and turbines and shipping in construction workers and construction materials, but also from the way the dam disrupts the ecology in which it sits.

When reservoirs build up behind gigantic shields of concrete, they flood and drown endless hectares of vegetation – trees, shrubs, savannahs, scrub. As the dead flora slowly rots, decomposing in the lower depths of pools of frigid reservoir water, it produces methane, which remains mostly stable, due to the way the water in the bottom reaches of the water is pressurized – although some still bubbles up to the surface. But when that methane-riddled water bursts through churning turbines, the methane dissolved in it shoots into the atmosphere, flooding it with a greenhouse gas significantly more potent than carbon dioxide. As Phillip Fearnside, the chief researcher focusing on tropical dams, especially in the Brazilian Amazon, comments, “The ultimate contribution of dams to carbon emissions is the difference between the carbon stock in the forest prior to flooding and that in the reservoir once the forest has decayed and an equilibrium is reached.” That can be a lot.

Dam reservoirs are effectively a form of deforestation, except the flooded areas will not regrow until they are unflooded, as opposed to clear-cut forests, which can regrow if they don’t undergo desertification. Once we see tropical reservoir creation as necessarily entailing deforestation, Green hydropower seems more like the pat advertising slogan that it is than the accurate description of reality that its boosters hold it out to be.

And what about the Asian mega-dams reliant upon Himalayan headwaters or dams in areas with relatively low stocks of vegetation, which won’t be veritable methane factories when massive tracts of land are submerged? Ask the experts. Anthropologist Thayer Scudder of Caltech, a member of the World Commission on Dams and formerly a consultant to the World Bank on dam projects, comments, “Climate change is going to very adversely affect big dams. These dams are going to meet relatively short-term needs. What’s the situation going to be 30 to 50 years from now, which is when they think the glaciers may be gone?”

The leading East Asian environmental historian Kenneth Pomeranz adds that the Himalayas are young mountains, with lots of dirt. As a result, the water that descends from them into South and East Asian watersheds and Bhutanese, Indian, Chinese and Nepalese dams are loaded with tons of dirt. Dam reservoirs will quickly silt up, giving the massively expensive dams abbreviated life spans – while the even slight vegetative stocks will be permanently removed from the bio-carbon cycle and the never negligible costs, pecuniary and ecological, of building the dams themselves will remain sunk. The peasants ushered off their land in the name of cheap energy won’t be building submersibles for algae farming either. Their lives will be permanently disrupted, as they shift to barely arable land or become additional unwilling émigrés to what urban theorist Mike Davis calls a planet of slums. It is for that reason that Pomeranz comments, “At least in the long run, technologies such as wind and solar seem much better bets to provide genuinely clean and affordable power.”

So, why are dams getting built willy-nilly? One could argue that it’s endemic short-sightedness, an affliction to which state managers under capitalism are particularly prone. But that’d only be part of the story. The other part is institutionalized bribery or, in the technocratic argot of climate change negotiations, the CDM. Through this bit of legislative chicanery, first world countries purchase carbon credits from third world countries, in effect paying for “green” infrastructure projects. In turn, the industrialized countries of the West can elect to postpone carbon reductions, since they’re already reducing carbon: just not in their economies, while third world countries get paid to develop clean energy sources so that they won’t dump even more greenhouse gases into an already overstuffed atmosphere. It’s all a bit of a stretch. At best: International Rivers Executive Director Patrick McCully argues, “This is a huge scam … Three-quarters of them are already built when they go for carbon credits. It’s hard to argue that they need the carbon credits to get built.”

So, can we get clean energy from moving water? Absolutely. Small dams might be built judiciously, while run-of-the-river dams, with turbines that don’t interrupt riverine flow, could also work well. And tidal dams might work, too, although they pose their own problems to marine life. But mega-dams? Not a chance.