Investigating the Potential Impact of Wind Farms on Lake Erie
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Our traditional energy sources are mainly non-renewable resources like coal and oil. These fuels, when burned, have a negative impact on our environment due to release of greenhouse gases, and they are not replenishable. So, the world needs other sources of energy to prevent an environmental crisis. Green energy produced from sources like wind, solar, geothermal and hydro, etc., is renewable and has much less impact on our environment. In our study, we focused on the potential impact of wind farms on Lake Eries dynamic and thermal structure. We used COHERENS (a Coupled Hydrodynamical-Ecological model for Regional and Shelf Seas) numerical software for the simulations. They were applied in 1 and 3 dimensions. In both cases, we used real wind speed and other meteorological data including atmospheric pressure, air temperature, humidity and cloud cover to simulate possible temperature and current variations over the ice-free season in Lake Erie. We worked on Erie, since this lake has the highest potential for offshore wind turbine installation due to its proximity to population centres and its shallow depth. In 1D mode, vertical profiles of temperature and water currents are driven by solar radiation and surface fluxes derived from observed three-hourly meteorological data, coupled with vertical mixing processes within the water column. Results are obtained for nine months of open (ice-free) water, March to November 2013, with different water depths of 10, 25 and 60 m. The model was run twice. In the second run, we used a reduced wind speed associated with the potential effect of wind turbines. For initial calculations, we used 25 percent reduction as a representative value. In 3D mode, we investigated the circulation and thermocline pattern for the months of May to October, 2005. As in the 1D mode, the model was run twice. The model is forced by solar radiation plus momentum and heat fluxes (sensible and latent) at the surface derived from North American Regional Reanalysis (NARR) and Canada Centre for Inland Waters (CCIW) data, plus initial conditions and with tributary flows represented as current vectors at river mouths. The Detroit River is the main inflow while outflow is via the Niagara River. With precipitation and evaporation balanced there was net zero accumulation of water in the basin. In the first run we explored water circulation patterns and the thermal structure (including the thermocline), of the lake and in the second run, we simulated the same parameters but added a large wind farm with 432 offshore turbines located in the shallow southern waters of the central basin. We compared our first run COHERENS output with both the Princeton Ocean Model (POM), and the Estuary and Lake Computer Model (ELCOM) results, run by the National Oceanic and Atmospheric Administration (NOAA) and the Canada Centre for Inland Waters (CCIW- Environment Canada), respectively. Generally, good agreement was achieved with these runs, which in turn had compared satisfactorily with field measurements. Results from the second run are used to estimate the potential impact of a large wind farm on the circulation and thermal structure in the areas of the lake within and around the wind farm.