In the green north of Spain, the Basque region has emerged as a renewable energy powerhouse over the last decade. Although high population density, mountainous terrain, and a lack of appropriate building sites have limited renewable energy production in the region, a number of Spain's most dynamic green energy firms have set up a dynamic manufacturing base there. With the wind energy market growing saturated, these firms have turned to solar and wave power. In the latter market, there is an interesting project going on in the coastal city of Mutriku which incorporates wave energy into breakwaters.
As the diagram below explains, the constant splash of small waves is captured through the inclusion of air chambers within the breakwater. As the waves enter and exit the chamber they drive air in and out, and these changes in air pressure are utilized to drive Wells turbines.
Recognizing that there was a need for a breakwater to be built to protect the harbor of Mutriku, the Basque regional government investigated the possibility of incorporating a wave energy component in a joint venture with Iberdrola, a regional power company.
Along 100 meters (~328 feet) of the break water a series of 16 Wells turbines was installed. Each turbine has an 18.5 KW capacity, for a collective potential of 296 KW. The estimated annual output is 600,000 KwH, yielding a capacity factor of 23.2%, roughly two thirds that of the average wind turbine.
The Basque regional government estimates that the inclusion of this turbine system (including work associated with the air chambers) added €6.4 million ($8.2 million) to the cost of the breakwater. The single largest component was civil engineering at €4.4 million ($5.7 million), followed by the costs of the turbines/transformers at €1.5 million ($1.9 million) and various licenses and tests at €0.5 million ($0.7 million).
That works out to €21.6 million/MW ($27.8 million/MW) or roughly ten times the costs of comparable capacity from wind turbines. Before you bail out here, remember that this was the first project of its kind, so costs will drop considerably as scale increases. Remember that the cost of wind power in the 1990s had dropped to roughly 1/10th the cost in the late 1970s. More to the point excluding civil engineering, the cost per MwH for a breakwater project falls to roughly $8.6 million/MW, which is probably a good proxy in the medium term (2-5 years) for costs.
Climate change has the ironic effect of making poor countries pay the price for the profligacy of the rich. Nowhere is this more apparent than in the low-laying nation of Bangladesh. As the image below shows, much of the nation lies less than a meter (3.3 ft) above sea level.
With the International Panel on Climate Change (IPCC) estimating that global sea levels will rise between 0.18 to 0.59 meters (0.6 and 2 feet) over the next century, the country faces a crisis. More imminent than the threat of being submerged is the simple fact that before any rise in sea levels is manifested in the water actually rising over low lying areas increased levels of erosion are likely. The waves will take the land to sea long before the land actually lies beneath the waves. Wealthy nations like the Netherlands already have extensive seawalls and breakwaters that will make this a managed process. In Bangladesh, poverty makes this a harder proposition. The country has a coastline of roughly 710 km (441 mi) that will need to be defended.
As if this wasn't bad enough, the country is industrializing. Although over half the population continues to lack access to electricity, Bangladeshi electric capacity has risen 70% in the last decade from 3,800 MW in 2000 (94% from fossil-fuel fired plants) to 5,376 MW as of 2010. This rate of growth will likely increase as the country becomes more integrated into world markets. Currently, Bangladesh has become a hub for textiles and clothing production. Nonetheless, per capita electricity consumption is 220 kwh (about 2% of American levels) meaning that there is a real need for that to increase. As the table below shows, this a country where investment in the electric infrastructure are needed.
As most power in the country is generated from fossil fuels, this creates a sad situation in which efforts to supply the population with electricity will only compound the threat posed by climate change.
But what if it doesn't have to be that way?
The technology being developed in the Basque country shows how this can happen. Breakwaters will need to be built in Bangladesh. These breakwaters can help solve the problem of increased emissions by generating electricity themselves.
The technology employed in the Basque Country has the capacity to produce 2.0-2.3 MW per km of breakwater. Bangladesh has 710 km (441 mi) of coastline. That means that using current technology, something like 1420-
1633 MW of capacity could potentially be supplied.
Two factors determine the ultimate potential here, and they are hard to quantify. First,it's hard to say how much of the coastline is appropriate for this type of project, suggesting that it will be somewhat smaller. Second, as first generation technology, these numbers might be low, because later models will likely produce more power at less cost.
Figuring on costs around $3 million/km for the actual sea wall, and another $9 million/km for the turbines and chambers, means $12 million/km.
For the whole 710/km coast, that's roughly $8.5 billion. Again, costs in Bangladesh are likely a fraction of that.
Figuring a 25% capacity factor, that's 3110-3576 GwH annually (12-13.5% of current net generation)
It's not a slam dunk, but the likelihood is that over the course of time technology of this sort will become both less expensive and more powerful making it more efficient and effective. The numbers here are to give a notion of the present potential, but the truth is that it's to early to tell. Yet, with the prospect of increased sea levels and erosion in the coming century upon us, it seems that it's time to consider ways to integrate power production into the defensive systems that are going to be needed to protect populations from the sea.