Energy from thin air

The renewable energy sources are more important than ever before. Wave or tidal energy hasn’t really been available in the Bothnian Bay, so we are looking at a possible future with a lot of offshore windmill parks in the SEAmBOTH area.

Calm sea and wind mils on the background.
Photo by Pekka Lehtonen, Metsähallitus.

Wind energy is a renewable and an infinite form of energy, but as green as it may sound, we still need to consider the consequences. Without going to the technology of producing the windmills or to the battery technology and the rare metals that they use, the effects that the offshore windmill parks have on marine nature can be both positive and negative. Some of the effects are still at guess work stage. We don’t, for example, know for sure, how the electromagnetic fields of the underwater cables affect the fish (Marcus C. Öhman, Peter Sigray and Håkan Westerberg, Offshore Windmills and the Effects of Electromagnetic Fields on Fish, Ambio Vol. 36, No. 8, December 2007). Or, to be more precise, we do know that the electromagnetic fields have an effect on fish, but we don’t know how the fish react to the growing number of cables at the bottom.

2 wind mils on suns shine.
Photo by Johanna Kantanen, Metsähallitus.

Large offshore windmill parks will, of course, have a large effect on the scenery. The horizon will be dotted with white windmills and some will find this a hugely negative issue while others may see it as a green energy scenery from the future.

Some of the effects that the windmills will have are bringing new habitats to monotonous sea bottoms. Right now, the wind energy field is focusing their planning to deep offshore areas which will, at least in the SEAmBOTH area, most probably be muddy bottoms. Bringing new structures to this kind of area will bring a new hard habitat to the world of only soft and pelagic habitats. This will enable fauna like the sponge animal Ephydatia fluviatilis or flora like water mosses or algae to attach to the new surface. This, in turn, will attract invertebrates to feed or hide in the vegetation and they will lure fish to the area to feed on the invertebrates. Windmill structures will also provide hiding places for fish, and many species of fish are generally attracted to large objects in the otherwise featureless soft sea bottom.

A wind mil in peaceful picture of sunset.  Water birds swimming past.
Photo by Pekka Lehtonen, Metsähallitus.

On the other hand, the windmill structure will destroy all benthic flora and fauna under the foundation, and the vibration of the windmill tower might drive away fish and seals.

The good thing about offshore windmill planning is that at least on the Finnish side, the companies have moved their focus from the shallow areas to deeper areas further away from the shore. With this move, the shallow areas, which are the ones with the most nature values like fish spawning grounds and underwater vegetation, will be spared from dredging and building. The scenery handicap will be the same, but there are remarkably less nature values in the deep offshore areas compared to the shallow nearshore areas.

Sea and 8 wind mils on the shore. Behind them is industrial activity and air pollutants.
Photo by Jussi-Tapio Roininen, Metsähallitus.

Now that the marine spatial planning (MSP) is under way in both Sweden and Finland, offshore windfarm areas are also put on maps. On the Swedish marine spatial plan, the windmill areas exist mostly south from the SEAmBOTH area. On the Finnish side of the SEAmBOTH project area, there are many opportunities for windmill park development. So many windmills have already been built on land and at least Finland is moving to the sea.

Written by Essi Keskinen


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