The Droop model is a mathematical model capable of predicting growth rates of algae whilst accounting for deficiencies in nutrient, such as nitrogen or phos­phorus. Nutrient uptake (nitrogen, phosphorus, vitamins, etc…) and biomass growth are known to be uncoupled processes for microalgae and the biomass is observed to continue growing for a few days after […]

CONTENTS 6.1 Droop Model……………………………………………………………………………………………… 212 6.2 Photosynthetic Factory of Algae Growth…………………………………………………….. 218 6.3 Cellular Automata Model of Wood Combustion………………………………………….. 225 6.4 Exercises…………………………………………………………………………………………………… 234 Biofuels are an important contribution to our energy supply, and have histor­ically made up the majority of our energy requirements (prior to fossil fuels). Legislative mandates are being enacted with the purpose […]

Wake models are computer models used to consider the coordinated distri­bution of wind turbines within a given region. In particular, a wind turbine extracts energy from the wind, and in turn slows down the speed of the wind downstream from the wind turbine. The effects of the wind turbine will de­crease with distance, and at […]

In the previous section we derived the Betz limit, where we considered how the change in momentum, as the rotor interacts with the air, and the motion of the air combine to give us a predicted ideal efficiency and a wake velocity. However, in the above analysis we didn’t take into consideration the geometry of […]

CONTENTS 5.1 Betz Limit…………………………………………………………………………………………………. 175 5.2 Blade Element Momentum Model………………………………………………………………. 180 5.3 Wake Models………………………………………………………………………………………. 194 5.4 Elastic Deformation of a Wind Turbine Blade……………………………………………. 200 5.5 Exercises…………………………………………………………………………………………………… 208 Wind power simply consists of extracting the kinetic energy from the wind and converting it to electrical energy. While the electronics and control system are an incredibly important […]

Solar cells capture incoming photons of light and, ideally, convert these pho­tons into free charge that can be extracted as electricity from the device. There are many steps in the process that influence the efficiency of the device, but the first step is how sunlight interacts with the solar cell. Initially, on reaching the top […]

Monte Carlo models are stochastic in nature. Typically, a Monte Carlo (ab­breviated MC) model will randomly sample the phase space of a system (for example, by allowing the constituents in a system to randomly relocate). As the phase space is randomly sampled, a new configuration is either accepted or rejected based on a stochastic scheme […]

In polymer solar cells the excitons dissociate at the donor-acceptor interface. The donor-acceptor interface is not always uniformly distributed throughout the polymer solar cell (as was assumed in the previous model). For example consider the charge carrier concentrations, in Figure 4.9, which can be numer­ically obtained in a polymer solar cell consisting of a bilayer […]