ACLIEMAC

One of the goals of the European Union (EU) is to reduce greenhouse gas (GHG) emissions. To this end, internal combustion vehicles (ICVs) will be progressively replaced with battery electric vehicles (BEVs) over the course of a transition period that is expected to last until 2035. While GHG reductions have been extensively evaluated for continental territories, this is not the case for territories with isolated electrical power systems, as in some islands of the EU. Emissions generated in these territories are considerably higher than in continental systems because their electricity generation mixes commonly have more polluting fuels. In this study, a calculation is performed of the CO₂ emissions that result from the charging of a reference BEV in the different isolated electrical power systems of the Canary Islands (Spain). The results are then compared with the CO₂ emissions of ICVs. Results show that the Canary electrical power systems that consume the least energy are the most contaminating and that charging a BEV entails higher CO₂ emissions than those generated by an ICV. In addition, no significant differences were observed between BEV- and ICV-related CO₂ emissions in the electrical power systems of the islands with higher energy consumption. A small decrease in CO₂ emissions was only observed in isolated insular systems with energy storage systems and high levels of renewable penetration.

Pressure retarded osmosis (PRO) is a process that is able to convert a salinity gradient into electrical energy
through a turbine. This process has gained attention as a possible renewable energy technology for integration into desalination plants to improve their energy efficiency. Despite recent efforts, PRO is not yet commercially available due to drawbacks related to, among others, PRO membrane and module development. The aim of this study is to provide a simulation tool for full-scale PRO systems that allows accurate estimates of PRO-related energy generation to be made. The proposed tool enables analysis of single-stage systems with PRO modules in series and the setting of boundary conditions per module in terms of maximum flux recovery, and maximum and minimum feed/draw flow. The HTI OsMem™ 2521 spiral wound membrane module (SWMM) was evaluated considering an 8 in. diameter (high active area).

Increasing the number of SWMMs in series was found to increase permeate flow and the energy that can be generated, even when considering the pressure drop on both draw and feed side and the effect of the dilution and concentration of the draw and feed solutions.

The proposed tool allows to determine the safe operating windows and operating points for maximization of energy generation for fixed and variable operating conditions.

Reverse osmosis (RO) is the most widely used desalination technology for both seawater and brackish water. Unfortunately, RO remains an energy intensive technology despite the efforts being made to overcome this drawback. One of the factors that could help to minimize this issue is the optimal design and operation of RO systems. Membrane manufacturers are continuously improving and releasing new spiral wound membrane modules (SWMMs) that nonetheless need to be studied in order to determine how to achieve the best highest possible performance from them. The aim of this study was to evaluate the safe operating windows (SOWs) of 9 commercial SWMMs in pressure vessels (PVs) with 7 of these elements in a single stage seawater reverse osmosis (SWRO) system. The permeability coefficients of the SWMMs were taken from a novel membrane open database.

These coefficients and the characteristics of the SWMMs were introduced in a simulation algorithm to estimate the behavior of the SWRO system. SOWs were determined without considering any energy recovery device, although these were considered for the calculation of the minimum energy consumption. The SWMMs were compared and the optimal operating points were identified for each one. The results showed the highest difference was around 0.2 kWhm-3 between SWMMs in their optimal operating point with respect to the minimum specific energy consumption. It was also found that this difference increases slightly with rises in feedwater concentration. For a wide range of PV power inputs, the SWMMs were able to reach quite similar maximum flux recovery rates. Experimental work is needed to obtain more reliable predictions of SWRO systems working in wide operating ranges.