Previously on the Green Blog, we examined several natural Islands that have managed to generate the majority, if not the totality, of their energy from renewable sources. These communities exist as a microcosm of the larger world, pioneering the application of alternative power sources on a utility-level scale. Green power Islands, however, represent a concept that would allow renewable energy to be applied to already thriving metropolises the world over.
A green power island is built around a variation on the concept of pumped hydro. In the case of El Hierro, a fully sustainable island in the Canaries which also utilizes the pumped hydro concept, wind power is used to move water into an elevated catch, from which it is released during low-wind periods to power electrical generators.
Developed by Copenhagen-based architectural firm Gottlieb Paludan, a green power island slightly modifies this concept by utilizing the construction of an artificial, sea-level lagoon as the central facet of a man-made island. Wind-driven power production is the main source of electrical generation in this concept, with excess power utilized to pump seawater out of the lagoon. When wind power is insufficient to meet production needs, seawater is then allowed to flow back into the island, powering generators in much the same way as the system on El Hierro, yet without the need for elevated storage.
The green power island concept removes certain limitations inherent with pumped hydro systems. An installation that relies on elevation is constrained by the size of its reservoirs and the difference in height between storage areas. By utilizing a man-made lagoon as the lower part of the system, a green power island essentially turns the ocean itself into an "elevated" reservoir.
Although the man-made island is primarily used for the storage of wind energy and hydrodynamic production as an alternative, it can also be utilized as a perfect platform for other renewable energy sources. In the concept design, green power islands can also house a concentrated solar collection plant, as well as an algae biomass. Tidal array power generation is nearly symbiotic with the infrastructure of a green power island, and with careful planning, such installations can be finely tuned to maximize the energy potential of seawater flowing into the island's basin.
As the lake at the center of the island will never fully be drained, it can be adapted for aquaculture purposes, which include seaweed as well as algae. Covering almost three square miles, a green power island could conceivably play host to beaches, harbors, recreation trails, or even business and residential construction.
For all of the inherent advantages, there are some concerns to be had over artificial islands. There are substantial engineering and environmental hurdles to clear during construction, to say nothing of economics. The sheer size of the undertaking involved presents a host of difficulties, not least of which is an uncertain environmental impact on a grand scale. The various ways in which a green power island will impact the seabed and surrounding habitat are subjective to each situation, and have very little precedent from which accurate projections can be derived.
Mixed-use planning is one way to mitigate these impacts, while the location of a green power island near a major metropolitan area would negate the need for energy transmission over long distances, potentially lowering the environmental impact of already extant infrastructure elsewhere.
While there are potential drawbacks, and a host of construction challenges to be surmounted when installing a green power island, Planet Save's Tom Schueneman notes that when viewed in the context of current energy production, the difficulties and scale seem eminently manageable.
"There are no doubt significant hurdles to overcome before Green Power Island could ever become reality," he points out. "Some might say that even if it were possible, it would be little more than a huge manmade offshore monstrosity. To those I would suggest, consider the options. We are digging deep into the ocean’s depths, wringing tar from sand, blowing the tops off of mountains – all for one more drop of oil, one more lump of coal. To most of us, this environmental destruction is largely out of sight, out of mind. That is, until disaster strikes, as surely it does, and surely it will."
Gottlieb Paludan has designed various green power islands that could potentially be constructed in Copenhagen, Denmark, as well as Tampa, Florida. Jiangsu, China, Tamil Nadu, India, and even Bahrain are also potential spots for the construction of green power islands, each adapted to the specific region and energy needs involved.