Surface structure on abandoned upland blanket peatland tracks

Temporary permissions are often granted for track use on peatlands. However, even when peatland track designs attempt to minimise environmental impacts via use of mesh systems, such linear disturbances may have persistent impacts. We evaluated the surface peatland structure of five abandoned tracks (four with a mesh surface, one unsurfaced) with varying past usage frequencies, at an upland site in northern England. Simplification of the surface nanotopography was found on all tracks compared to surrounding control areas, with increased micro-erosion patterns in rutted areas, and invasive species on some treatments. The frequency of previous usage was not found to be a significant factor controlling nano-topographic loss. Edge effects and hillslope position were influential in places, but these effects were not consistent across treatments. Nano-topographic recovery was found to be inhibited when track usage commenced within a short time frame after track construction. Mesh tracks appear to create a spatial constraint leading to poor development of plants and a reduced ability to form characteristic structures which are integral to mire function

Impacts of peat bulk density, ash deposition and rainwater chemistry on establishment of peatland mosses

Background and aims Peatland moss communities play an important role in ecosystem function. Drivers such as fire and atmospheric pollution have the capacity to influence mosses via multiple pathways. Here, we investigate physical and chemical processes which may influence establishment and growth of three key moss species in peatlands. Methods A controlled factorial experiment investigated the effects of different peat bulk density, ash deposition and rainwater chemistry treatments on the growth of Sphagnum capillifolium, S. fallax and Campylopus introflexus. Results Higher peat bulk density limited growth of both Sphagnum species. S. capillifolium and C. introflexus responded positively to ash deposition. Less polluted rain limited growth of C. introflexus. Biomass was well correlated with percentage cover in all three species. Conclusions Peat bulk density increases caused by fire or drainage can limit Sphagnum establishment and growth, potentially threatening peatland function. Ash inputs may have direct benefits for some Sphagnum species, but are also likely to increase competition from other bryophytes and vascular plants which may offset positive effects. Rainwater pollution may similarly increase competition to Sphagnum, and could enhance positive effects of ash addition on C. introflexus growth. Finally, cover can provide a useful approximation of biomass where destructive sampling is undesirable

Blanket bogs exhibit significant alterations to physical properties as a result of temporary track removal or abandonment

Temporarily consented tracks made from high-density polyethylene (HDPE) mesh have been used to mitigate both the physical and ecological impacts on peatlands from low-frequency vehicle usage. However, the impacts of mesh track removal or abandonment at the end of the consented period remain poorly understood. Over a 2-year period, we studied replicate sections of abandoned mesh track which, at the start of the experiment, had been unused for approximately 5 years, on a UK blanket bog. Some sections were removed (using two treatment methods – vegetation mown and unprepared), whereas others were left in situ. Metrics were compared both between treatments and to undisturbed reference areas. Significant differences in surface soil moisture were found between abandoned and removed tracks depending on season. Control areas had higher volumetric soil moisture than track locations. Compaction was significantly higher across all track locations in comparison to controls (p < 0.001), but rarefaction was not recorded post-removal, suggesting long-term deformation. Overland flow events were recorded in rut sections for a mean of 16% of the time, compared to <1% in control areas. Sediment traps on the tracks collected 0.406 kg compared to 0.0048 kg from the control traps, equating to a per trap value of 7.3 g from track samplers and 0.17 g from control samplers. Erosion and desiccation features occurred on both removed and abandoned track sections. Both abandonment and removal of mesh tracks have a wide range of impacts on the physical properties of peatlands, suggesting that only where access is a necessity should such a track be installed

Floating Wind Offshore Turbines - Installation Engineering

This is the final version.Institution of Mechanical Engineers - Wind Turbine User Group 2023, 17 - 18 May 2023, London, UKFloating offshore wind turbines are an emerging source of marine renewable energy. Installation engineering of these large floating structures is required to provide confidence to owners and insurers that they are constructed in a safe and cost effective manner. This paper covers the construction and installation of various substructure types including barges, Spars, semi submersibles and tension leg platforms. This paper details the engineering requirements for installation vessels and large onshore cranes required for the construction of floating substructures that support offshore wind turbines. Each of the installation phases, such as load-out, fit out, tow out, mooring connection and cable laying poses challenges in the use of existing technology and the development of new installation techniques. The presentation will give an overview and comparative analysis of lessons learnt for offshore installation of floating offshore wind turbines. 3 key phrases i. Floating wind turbines nearshore construction ii. Requirements for installation vessels and onshore cranes for floating wind iii. Technical advances for floating wind installatio

Floating offshore wind turbines installation methods

This is the final versionFloating offshore wind turbines are an emerging source of marine renewable energy, in deep water offshore locations, with minimal visual impact from the shore. The presentation reviews the installation methods for floating wind types such as barges, Spars, semi submersibles and TLPs and offers suggestions for improvements. This floating wind presentation will be useful for stakeholders in the offshore wind engineering sector who are offering installation solutions for floating wind installations. The overview of the installation challenges for different substructure types will provide important information to developers of floating wind

Installation Aspects of Floating Offshore Wind Turbines

This is the final versionFloating offshore wind is an emerging source of marine renewable energy. The installation of floating wind turbines can take advantage of the UK oil and gas industry and the fixed offshore wind platforms. The presentation reviews the installation development of different types of substructure namely: barges, Spars, semi submersibles and TLPs. The installation challenges for the various substructure types are investigated and suggested areas for future development for floating offshore wind are included. Design for installation includes expanding the weather window in which these floating substructures can be transported to site and facilitate mooring and electrical connection. The simplification of installation methodology will reduce time spent offshore and minimises risks

Port and shipyard requirements for the installation of floating wind turbines

This is the author accepted manuscript. The final version is available from the Royal Institute of Naval Architects via the link in this record As the floating offshore wind turbine industry continues to develop and grow, the capabilities of established port facilities need to be assessed as to their ability to support the expanding installation requirements. This presentation assesses current infrastructure requirements and projected changes to port facilities that may be required to support the floating offshore wind industry. Understanding the infrastructure needs of the floating offshore renewable industry will help to identify the port-related requirements. The naval architecture aspects of port development include loadout ballasting and mooring, intact stability during floatout from a drydock and fit out of turbine components. The capabilities of established port facilities to support floating wind farms are assessed by evaluation of size of substructures, height of wind turbine with regards to onshore cranes for fitting of blades, distance to offshore site and offshore vessel characteristics. In addition large areas are required for laydown of mooring equipment, turbine blades and nacelles. The floating offshore wind industries are in early stages of development and port facilities are required for substructure fabrication, turbine manufacture, turbine construction and maintenance support. The presentation discusses the potential floating wind substructures to provide a snapshot of the requirements at the present time, and potential technological developments required for commercial development. Scaling effects of demonstration-scale projects will be addressed, however the primary focus will be on commercial-scale (30+ units) device floating wind energy farm

Port and installation constraints of Tension Leg Platforms (TLP) floating wind turbines

This is the final version.Floating offshore wind needs to go from pre commercial phase to full commercial use if it’s full benefits are to be realised. The port and installation requirements for barge, semi submersible and Spar substructure types are understood, though more research is needed to reduce cost. Floating Wind Tension Leg Platforms (TLPs) have constraints on tow out intact stability and complications in installing the tension moorings. The paper will review the port and installation requirements of TLPs as floating wind substructures. The TLP has the advantages over other substructure types for low in place motions and minimum area taken up on the seabed. There is experience from the offshore oil and gas industry of TLPs which can assist in developing cost effective TLP designs for floating wind. The priorities are the turbine fit out port and the vessels required for TLP offshore installation. Cost reduction during the port and installation phases are based on the best techniques from the offshore oil and gas industry, from bottom fixed wind turbines and the installation of other floating wind types. Installation methods considered are: variable draft between tow out and operations, piece small installation offshore and fitting temporary buoyancy for the tow out phase. Design for installation includes expanding the weather window in which the TLP floating substructure can be transported to site and configurations to facilitate mooring. The simplification of installation methodology will reduce time spent offshore and will minimise risks to personnel

Challenges during installation of floating wind turbines

This is the author accepted manuscript. The final version is available from ASRANet via the link in this recordFloating wind turbine substructures are an expanding sector within renewable power generation, offering an opportunity to deliver green energy, in new areas offshore. The floating nature of the substructures permits wind turbine placement in deep water locations. This paper investigates the installation challenges for the various floating offshore wind types and suggests priority areas for future development to help reduce costs. Specifically tailored design for installation includes expanding the weather window in which floating substructures can be transported to and from site and making mooring and electrical connection operations simpler. The simplification of installation methodology will reduce time spent offshore, by installation vessels, and minimise risks to personnel. The paper reviews best towing practice for offshore installation and the possible return to port for maintenance. The installation process for a floating offshore wind turbine varies with substructure type e.g. Barge, semi-submersible, Spar and TLP which are discussed in detail. TLPs will need temporary buoyancy or specialised offshore crane vessels to enable installation of these substructures. Spars require deep water for construction and tow out. Return to port for maintenance is only feasible for Barges and semi-submersibles Floating offshore wind structures require an international collaboration of shipyards, ports and installation vessels, The installation phases, in particular the maximum draft of the substructure, are affected by the construction materials i.e. steel or concrete. . Steel Semi Submersibles and Barges, have a smaller draft than concrete substructures, and thus require out-fit quays with less water depth. In order to facilitate the installation and to minimize costs, the main aspects have to be considered strategically i.e., the required vessel types, the distance from fit out port to site and the weather restrictions. The fit-out port should be as close as possible to the offshore installation site to minimise weather downtime during tow-out. Of the main substructure types, the Spar has the greatest average installation cost, driven by the vessel requirements and the sheltered/calm conditions required for turbine assembly. The nature of the Semisubmersible substructure and its moorings lead to lateral movement of the turbine, which presents a challenge for the export cable connection. This paper will be useful for researchers and stakeholders in the offshore wind and offshore engineering sector offering or considering technology solutions for floating offshore wind installationsEngineering and Physical Sciences Research Council (EPSRC

Celtic Sea - Installation of Floating Offshore Wind Turbines

This is the final version.Floating offshore wind turbines are part of the future for marine renewable energy. Both demonstrator and pre commercial floating wind turbines are being considered for installation in the Celtic Sea. As the floating offshore wind turbine industry continues to develop, the capabilities of new crane vessels can play a crucial role in their installation. This presentation assesses current installation vessel requirements and capabilities in particular for installing the moorings and sub sea cables . The water depths, average wind speed and potential areas of the Celtic Sea are discussed. The naval architecture aspects of floating wind turbine installation for tow out include intact stability, bollard pull and motions. In addition as the floating offshore wind turbine is being installed there are motion considerations of connecting mooring lines and electrical cables. The floating offshore wind industry is in early stages of development and installation vessel requirements are still being considered. The presentation discusses the potential of different floating offshore wind substructures types for installation in the Celtic Sea