Life cycle analysis of the embodied carbon emissions from 14 wind turbines with rated powers between 50Kw and 3.4Mw

In order to facilitate increased renewable energy production, there continues to be a global increase in wind turbine installation. When quantifying the carbon offsets from these installations, the production emissions are rarely accounted for. This paper reports on the embodied carbon emissions from the production of 14 wind turbines, rated between 50 kW and 3.4 MW. The embodied emissions were quantified from emission factors specific to each material involved in manufacture, transport to site, and installation of the turbines. The resulting trend was that higher-rated turbines had greater embodied carbon emissions with one 3 MW turbine incorporating 1046 tCO2eq compared to only 58 tCO2eq for an 80 kW turbine. However, the greater electricity output of the turbines offset these emissions more quickly with a recovery in 64 days for a 3.4 MW turbine compared to 354 days for a 100 kW one. This also resulted in lower carbon emissions per kilowatt hour of electricity generated and quicker payback as a percentage of lifetime of 0.9% for a 3.4 MW turbine compared to 4.3% and 4.9% for a 50 and 100 kW turbines, respectively. The findings of this analysis indicate that a preference for installation of higher-rated, over lower-rated, turbines should be favoured for greater environmental benefits

Improved sustainability and ecosystem services from seaweed additions to an old agricultural production system

Throughout the UK, and in other areas of the northern hemisphere, where there has been human settlement from the 17th century onwards, evidence of parallel ridges can still be seen today. These ridges, sometimes called lazy beds, are a remnant of a production system that offered small, often remote communities cropping potential on land that would be considered today as less favourable or unsuitable for production. With a move away from this type of small-scale, labour-intensive production system, over the last century, communities in these areas have generally undergone a shift from self-sustainability to a reliance on the importation of human and animal feed. This has led to abandonment of these cultivation systems. As modern communities become increasingly dis-associated from historic cultural practices, living memory of the management of these systems is also now being lost. There is an argument in support of restoration of these historic systems, in light of rising global pressures for both sustainable food security and land availability for agricultural production. Such restoration should be underpinned by, scientific understanding as to how these methods were able to provide a sustainable system for cropping and yield over time, and the environmental impacts of these systems. A project has been established on the island of Grimsay (North Uist) to reinstate a series of abandoned ridges, which have not been worked in over 50 years. As part of this project a series of studies have been initiated to examine the historic management practices (and their impacts) associated with these agricultural systems. A pilot study was run to determine if the traditional use of seaweed (particularly Ascophyllum nodosum) was of benefit, or indeed essential, to the longevity of these rotational systems. This trial was placed within the wider context of an experiment investigating the ecosystem impacts of reinstating this type of agricultural practice and its utilisation of local, natural resources. The findings of the pilot study indicated that historical knowledge is essential in reinstating this type of production, seaweed is both a required and sustainable addition to the system, ecosystem impacts were minimal and that production was both viable and greatly increased when labour was available

Marine macroalgae as food for earthworms: Growth and selection experiments across ecotypes

Historically, subsistence farmers around the Atlantic coast of NW Europe utilised marine algae as a fertiliser in agroecosystems, a practice that continued in small areas and is now considered to have real potential for re-establishing sustainable food production systems on marginal soils. Earthworms form a significant component of soil fauna and their ecosystem services are well documented. Therefore, palatability of marine organic amendments to faunal detritivores of terrestrial systems is of interest. This work aimed to assess the potential for growth of Aporrectodea caliginosa, Lumbricus rubellus and Aporrectodea longa fed with two common macroalgae (seaweeds), Laminaria digitata and Fucus serratus. In addition, choice chambers were constructed to permit earthworm selection of these macroalgae with more conventional organic materials, horse manure (HM) and birch leaves (BL). Over a period of two months, earthworm species showed significantly greater mass gain with conventional food (p<0.05). Laminaria outperformed Fucus, which in turn was superior to soil alone. Similarly, when given a choice, a significant preference (p<0.001) was shown for the more nitrogen-rich HM and BL over the seaweeds. No removal was recorded for A. caliginosa when offered seaweeds only. By contrast, L. rubellus and A. longa showed significant preferences (p<0.001) for Laminaria over Fucus and fresh material over degraded. These results underline an interest to profit from natural resources (seaweeds) to maintain or improve soil biological quality in marginal coastal areas