Since the Deepwater Horizon disaster, the U.S. media and public have begun to focus in earnest on the risks and uncertainties associated with maintaining our reliance on fossil fuels as resources in ever-more-remote and hostile environments are exploited.  The April 20 blowout and subsequent release of vast quantities of oil and methane into the Gulf of Mexico has captured the public’s attentions and sparked many a passionate debate over our need to maintain something like current oil  production levels to satisfy our dependence versus the need to actively build a transition to more sustainable sources of energy for the future. 

What path will we choose once the smoke clears?

The New York Times, for instance, recently published a letter of mine (#2 here) written in response to an article calling for an end to President Obama’s moratorium on new offshore wells until new safety and oversight standards can be developed to prevent a repeat of the incident.  While nobody can or should minimize the economic impact of temporarily shutting down one of the Gulf Coast’s largest industries, by the same token, nobody should be rushing to reopen waters to new drilling unless and until measures are put in place to ensure that the technology is truly ready and that such careless practices as led to the Macondo blowout will never again be allowed.  I would support a requirement for relief wells to be pre-drilled and ready to go in case of any future incidents, to prevent the months of delay and gushing oil we have seen in response to this crisis.  If that means the price of gasoline goes up, so be it: that is what we call appropriate risk pricing.

Deepwater Disappointment

One point that has been largely missed in the discussion of economic impacts from both the blowout itself and the drilling moratorium that followed is that while expensive deepwater oil may provide economic benefits for the Gulf of Mexico, it is not so good for the economy of the rest of the United States or the world.  Rising oil prices from more expensive projects result in higher costs not just at the pump, but also for all goods and services whose production or transportation depends upon oil, including the most basic and necessary commodity of all: food.  I posted an article recently discussing the staggering production decline at Thunder Horse, the largest offshore field under development in the Gulf of Mexico, which illustrates the tremendous uncertainty involved in estimating reserves and production rates even when deepwater fields come online successfully.  Other, smaller Gulf of Mexico deepwater projects have largely met with similar results.  A similar story appears to be unfolding at an even larger scale off the coast of Brazil, home of Tupi, a complex of oilfields believed to be the largest find in the past thirty years.  Discovered in 2006, the first exploration wells came online in 2008 during that year’s dramatic spike in oil prices, but no production wells have been drilled since prices crashed later that year.  The field presents unprecedented technical challenges, as the oil sits below a layer of salt which acts as a fluid under such pressures as are found in the depths being explored (and drilling through fluid is not exactly easy).  While Tupi oil is likely to come online eventually, you can say you heard it here first: it will be slow, expensive, and energy-intensive to produce.  Don’t be deceived by high initial reserve estimates.

Tupi and adjacent deepwater oil fields, image from offshore-technology.com

For the past decade, many petroleum executives and peak oil skeptics have argued that plenty of oil remains to be found if we adequately explore the deep recesses of the seventy percent of the Earth’s surface covered by ocean.  The best available evidence today suggests that such exploration will be far more expensive and risky, and far less productive, than the optimists have suggested.  However, it is worth noting that drilling for deepwater oil resources is far from the only way to harness energy from our planet’s vast expanses of ocean.  Renewable ocean energy technologies are in their infancy today, but it is far from unreasonable to suggest they may ultimately provide the majority of the energy needs of the planet’s human population.  Many of the same developments that have made shallow- and eventually deepwater oil resources viable and competitive sources of energy may ultimately stand to benefit renewable ocean energies as well due to considerable overlap in the technologies used.  By combining technology to utilize these energies with electrified transport options, which have the advantage of flexibility in their source of primary energy, we could reduce or even eliminate the reliance of the transportation sector on high-quality but non-renewable and depleting liquid and gaseous fuels.

Let’s have a look at three types of renewable power to be harvested from the seas, starting with technology that has already been commercialized in Europe and soon to be built in the United States, then moving to more experimental but also proven and scaleable technologies that are likely to come into play in the coming years and decades:

Offshore Wind: Harder, Better, Faster, Stronger

Onshore wind power represents some half of all new installed electric generating capacity in the United States today, and as costs have come down and performance has improved, wind power has become the most cost-effective source of new electric power production in many areas.  The United States is blessed with the world’s best wind resource, but the best winds have yet to be utilized for energy production: those blowing some 150 meters above the surface off the shores of the Atlantic, Pacific, and Great Lakes.  While offshore wind energy production is more capital-intensive and technically challenging than conventional onshore wind, the experience of installing and operating some two to three gigawatts of offshore wind power in Europe over the past two decades has already helped to resolve many of the challenges; for instance, nacelles at Denmark’s Horns Rev offshore wind farm had to be replaced due to marine corrosion, and today all offshore wind turbines are built with pressurized nacelles to prevent corrosive elements from sea spray from entering the gearbox and drivetrain.

Offshore wind has two performance advantages over conventional wind power that may allow it to supply something that resembles the energy-dense baseload power supplied today by coal and nuclear plants.  First, offshore winds blow faster and more reliably than continental winds, allowing capacity factors of 50% or higher to be achieved, compared to 30% or so from onshore turbines.  Higher capacity factors are also easier to achieve using high-altitude winds, and larger and taller offshore turbines give the combined advantage of greater power output and higher capacity factor.  Second, each turbine can provide a greater power output than an onshore turbine: it is easier to ship the large components necessary to build large turbines by barge than to ship them over land by truck and rail, and the power output of a given turbine is proportional to its swept area, and hence its size.  Today’s onshore turbines produce power in the range of 1.5-2 megawatts, but most analysts expect offshore turbines in the range of 5 megawatts or more.  Today’s manufacturers are already beginning to offer direct-drive turbines without gearboxes at around 4 MW, which could considerably reduce costs of installation by eliminating a great many moving parts from the nacelle.  Matt Simmons’ Ocean Energy Institute has proposed building turbines as large as 50 MW; theoretically, there is very little to limit the size of offshore wind turbines.  The only true limiting factors are what is achievable given today’s materials and offshore construction equipment, and the use of lightweight materials such as carbon fiber and simplification of the technology through direct-drive turbines and other innovations offers considerable promise for developing larger and better wind turbines going forward.

Wind turbines can take advantage of cost reductions available through utilization of other offshore-platform construction technologies.

Wave Power: Wave of the Future?

Ocean waves embody considerable energy: it takes a lot of power, driven by winds and circulation of ocean currents, to move all that water up and down.  The energy to be potentially harnessed from waves is measured in kilowatts per meter, which gives a sense of the considerable energy density that would be available if the technology to do so is commercialized.  The primary challenge in harnessing wave power, in fact, comes not from the low energy density often cited as a criticism of renewable energy, but the very opposite: wave power systems must be designed to be robust enough to survive not just the mild movements of water that would be needed to generate power commercially, but also the occasional highly energetic event like a tsunami or hurricane.  Fortunately, businesses like Oyster Energy are up to the challenge of building reliable machines to convert wave energy into commercial power.  The company has been testing its 800 KW system over the past few years and recently acquired funding to deploy the first commercial wave energy systems in the UK.  The tremendous potential of wave power, especially for the majority of the world’s population that lives near coastlines, demonstrates that various sources of ocean power are very likely to make waves as we evaluate the feasibility of sustainable energy technologies for the twenty-first century and beyond.

Estimated worldwide wave power potential in kilowatts per meter, 2007; by some estimates waves could provide over twice the world’s current energy needs.

Ocean Thermal Energy: Rising to the Occasion

Ocean thermal energy conversion, or OTEC for short, refers to technologies that utilize the temperature differential between the upper and lower layers of the ocean to drive a heat engine.  The fundamental premise is the same as that used in geothermal, solar thermal, and even convential thermal power plants such as coal and nuclear plants: power is derived from the flow of heat from high-temperature to low-temperature reservoirs.  Cold water is drawn up to the surface using a long submerged pipe in order to provide the cool reservoir.  The best ocean thermal resources are therefore located in tropical and subtropical deep waters, where very warm water is available at the surface and very cold water in the depths.  While OTEC might seem like nothing more than a pipe dream at first glance, the technology has already been shown to be viable and in some cases, such as in Hawaii and other island settlements, already cost-effective compared to extant power generating systems.  Lockheed Martin holds many patents related to OTEC power production, and a 70 KW-net pilot plant was operated for seven years in Hawaii before OTEC research was de-funded during the Reagan administration.

Ocean thermal energy systems have three primary cost elements: the platform, the cold water pipe, and the heat exchangers.  Advances such as prefabricated cold water pipes made from cheap, lightweight composite materials, new technologies to more cheaply utilize low-grade thermal resources to generate power in advanced geothermal and solar thermal applications, and new offshore-platform construction techniques, all have the potential to significantly lower the cost of OTEC technology in the coming years.  Another advantage of some OTEC systems is the ability to produce desalinated water as a byproduct.  The temperature differences that exist naturally in our oceans therefore offer a practical and viable resource, especially in regions scarce in both energy and fresh water resources.

None of the energy sources described above are able to directly substitute for oil used in transportation, at least not without a simultaneous investment in electrified transport.  But the tremendous potential for offshore wind, wave power, and ocean thermal energy demonstrates that we have yet to tap into some of the largest and best renewable energy resources available.  Many of these technologies are in their infancy today, but they have all been shown to be technically feasible, and they demonstrate that we need not feel trapped by reliance on fossil fuels, an assumption that continues to dominate in discussions of our energy future.  The above represents just a handful of the high-quality, dense renewable energy flows available to us, should we choose to develop the technology and build the political willpower needed to make the switch.  With even modest increases in the price of fossil fuels, all but inevitable given the increasing difficulty of accessing such resources and their various environmental externalities, commercial investment in renewable ocean power seems highly likely to take place, and sooner than you might think. 

Now, now…no need to get all blown out over one deepwater disaster!