A Green Energy Dilemma?

The demand for energy has increased by 3.6% in the past 30 years (Saidur et al, 2011). Renewable energy sources are consistently proposed as ways of meeting this demand whilst reducing our CO2 output, thus slowing down our contribution to climate change, and also of halting our unsustainable use of fossils fuels. All renewable energy sources have their critics, though, and Wind Turbines often generate protest when someone proposes constructing a wind farm.

There's the NIMBY (Not In My Back Yard) groups who claim they're a blot on the landscape, and there is large concern that homes near wind-farms lose up to a third of their value (Express & Echo, 2013). It is no surprise that recent plans to construct turbines in Ireland (Telegraph, 2014), Wales (WalesOnline, 2013) and Scotland (BBC, 2013) have been opposed. Personally I find wind-farms a pleasant site, though that might have something to do with having grown up in the industrial north with Teesside power-station, the former ICI (now Syngenta) chemical works, and the Hartlepool nuclear power-station sandwiching my home-town. If they're being built out at sea, there are still groups who claim they're aesthetically unappealing, and then there's the issue of cloud formation behind the turbines, that may reduce visibility and pose threats to sea-faring vessels (Emeis, 2010).

My focus upon both onshore and offshore wind-farms, however, will be the apparent threats they pose to bats and birds. Are the number of fatalities of flying animals really as high some groups make them out to be? And do wind-farms result in more or less deaths than other methods of energy production?

Saidur et al (2011) proclaim that wind energy "is the energy source that is most compatible with animals and human beings in the world". Though bird mortality does occur, wind turbines have been demonstrated to kill fewer birds (~20 times) than fossil fuels, and many more times less than human activities. Amongst anthropogenic causes, building windows largest cause of bird mortality with 97-976 million deaths a year. Pesticide poisoning causes a further 72 million deaths, direct hunting more than >100 million deaths, and collisions with cars and trucks around 50-100 million fatalities. (Sovacool, 2013)

A recent study by Sovacool (2013) estimated that whilst fossil fuel power stations are responsible for roughly 5.2 deaths per gigawatt-hour (Gwh) of electricity, wind farms and nuclear power stations only account for between 0.3 and 0.4 fatalities. In the USA alone, this estimate means that an estimated 20,000 birds have been killed by wind farms in 2009, but over 14 million by fossil fuel power plants.

The number of avian deaths per year in 2009 in the United States - from (Sovacool, 2013).

There are direct and indirect ways in which electrical generation can impact upon birds and other wildlife. Wind farms pose threats during their construction, and the construction of associated infrastructure; large areas of land, roughly 2.5 acres per turbine, are also required (Katz, 2010). Fossil fuel stations post the same threats, and even more. Emissions such as mercury, which is especially a threat to water birds, may lead to fatalities. Acid rain pollution is another threat, causing an estimated 0.5 deaths per GWh, and climate change as a result of CO2 equates to around 4.98 deaths per GWh.

The number of bird and bat collisions with turbines has been show to correlate with weather conditions, with poor weather leading to a greater number of fatalities (Saidur et al, 2011)(Sovacool, 2013). Poor visibility, rain and high winds may lead to birds flying at lower altitudes, becoming disorientated, and birds may become attracted to lights around the wind farms, thus increasing the chances of collision. (Saidur et al, 2011). Older turbines also pose a greater risk as turbines are often spaced more closely and have blades rotating at higher speeds. The lattice-shaped towers of older turbines may also attract nesting birds (Saidur et al, 2011).

Though collision is an issue, the greatest risks to bats appears to be the rapid reduction of air pressure around wind turbines, which leads to fatal barotrauma; the rupturing and internal haemorrhaging of bats' lungs. Barotrauma is not an issue for birds, as their lungs are more adapted to sudden changes in pressure (Sovacool, 2013).

Overall, it is undeniable that Wind Farms pose a threat to birds and other avian animals, but the threats are much less than those of Fossil Fuel plants. I think it important that instead of fighting against protests against wind power, that we instead focus upon ways to reduce the risk to birds and bats, and ways to decrease their offensiveness towards people.

Wind turbines on the Isle of Lewis, Scotland - image by Lews Castle UHI on Flickr.

Minimising motion smear, the blurring of the tips of the turbine blades because of their high speed, has been proposed by Hodos et al (2001) as a way to reduce avian collisions with turbines. They suggest that patterning the blades of the turbines will help birds see turbines more clearly.

Active damping systems may help neutralise the low buzzing noise that wind turbines give off, thus allowing them to be operated at a full load whilst not disturbing local residents (Alternative Energy, 2008). An alternative to building traditional turbines may be instead to use existing infrastructure for wind turbines, such as placing them inside of electricity pylons. By locating the turbines in or on existing structures, complaints that they are an eyesore may be reduced (Alternative Energy, 2009). In China, street lights have been erected in PingQuan with small wind turbines (and two solar panels) atop each structure (Urban Green Energy, 2012); small scale projects like this may be useful for powering local infrastructure, thus reducing the amount of energy required from other sources.

Bird Friendly Tuna?

Many albatross and petrel deaths attributed to pelagic long-line fishing for tuna and similar species in the southern hemisphere. In a study of seabird deaths due to pelagic longline fishing in the southern Atlantic Ocean between 2004 and 2008, Yeh et al. (2012) estimated that between 3446 and 6083 birds were killed per year. These deaths lead to many breeding-site populations reducing in number (Roberston et al, 2013).

A shoal of Skipjack Tuna (Katsuwonas pelamis) - image
from Wikipedia Commons.

There are ways to reduce mortality, such as setting lines at night, but this method -and several others- may mean that industries are unable to set their lines at times that optimise catch rates.

Robertson et al. (2013) suggest that focusing on branch-line weighting may be a way of reducing mortality rates of seabirds in the Australian fishing industry. Weights are not a new innovation in longline fishing, but Robertson et al. (2013) carried out experiments that differed from previous weighting methods. In their tests, weights were positioned differently upon the lines; in the first test, a 120g weight was placed ≤ 2m from the hook, and in the second test a 40g weight was placed directly at the hook. The purpose weighting the lines is to reduce time it takes for the hook and its bait to sink, thus reducing risks to seabirds by reducing the exposure of bait at the surface where birds may become caught.

Concern is often expressed that weights reduce catch, but Robertson et al. (2013) found no reduction in catch rates of Yellow-fin tuna; rather, catch rate correlated with bait type. For the other species caught, neither weighting or bait type seemed to have an effect on catch rates.

Though the heaver weighting method had faster sink rates, the authors acknowledged the implications of the extra weight in the gear bins. For this reason, they suggest using the lighter weighting method. They also indicate concerns for the loss of lead weights through shark bite-offs. Though not so much an economic problem, there is some concern that lead weights will become deposited on the seabed, or that they could be swallowed by sharks which may be later caught for human consumption. A way round this dilemma would be the replacement of lead with another substance.

Robertson et al. (2013) also state that loss from bite-offs may be minimised by placing weights on shorter leads; having the weights nearer hook is also safer for members of the fishing crew, as their experiments show such placement to reduce 'fly back' of the weights when hooks are bitten off. Other benefits they raise are reduced labour times for fishing crews due to less tangling and less like breakage (and therefore less repairs) of lines, as well easier line deployment.

New weighting regimes therefore seem like a win-win situation for both seabirds and the fishing industry. I just don't think the tuna will be all that happy...