Concepts of rainwater harvesting and its role in food security: the Ethiopian experience

Water harvestingFood securityIrrigation

Climate policy costs of spatially unbalanced growth in electricity demand: the case of datacentres. ESRI Working Paper No. 657 March 2020

We investigate the power system implications of the anticipated expansion in electricity demand by datacentres. We perform a joint optimisation of Generation and Transmission Expansion Planning considering uncertainty in future datacentre growth under various climate policies. Datacentre expansion imposes significant extra costs on the power system, even under the cheapest policy option. A renewable energy target is more costly than a technology-neutral carbon reduction policy, and the divergence in costs increases non-linearly in electricity demand. Moreover, a carbon reduction policy is more robust to uncertainties in projected demand than a renewable policy. High renewable targets crowd out other low-carbon options such as Carbon Capture and Sequestration. The results suggest that energy policy should be reviewed to focus on technology-neutral carbon reduction policies

Kinetic investigation and optimization of a sequencing batch reactor for the treatment of textile wastewater

Discharging of untreated or partially treated textile wastewater is common in Ethiopia, and this has detrimental effect to the environment. It is difficult to treat textile wastewater by conventional biological processes. In this study, real textile wastewater was taken and treated using sequencing batch reactor using a biomass taken from domestic wastewater treatment plant. Cycle period, air flowrate and sludge retention time (SRT) were initially optimized using the response surface methodology. The optimum ratio of cycle period/air flowrate/SRT which gives a 57% COD removal and 54% color removal was found to be 25 h/15 L/h/16 day. Using two types of wastewater substrate concentrations and various hydraulic retention times at optimized condition, COD removal, color removal, sludge volume index (SVI) and mixed liquor suspended solid were measured. The maximum of COD removal (73%) and color removal (65.8%) was obtained at an organic loading rate of 0.078 kg COD/m3 day. SVI at the optimized condition was found to be 90–92 mL/g. Finally, a first-order kinetic model was used to represent the degradation of textile wastewater

Characteristics of fungi contaminant in tissue culture of Bromheadia finlaysoniana (Lind.) Miq

Generative propagation of orchid plants has problems because orchid seeds do not have endosperm that need to be multiplied using tissue culture. Contamination is a limiting factor in the multiplication of plants in tissue culture. This study describes the types of contaminants found in Bromheadia finlaysoniana callus. This research was carried out in two stages. The first stage is carried out culture of various explants of Bromheadia finlaysoniana using murashige and Skoog media with enrichment of hormone Benzylaminopurine 1 mg/l; (Naphthalene acetic acid) 0.5 mg/l; 100 mg mynositol; pyridoxine-HCl 0.5 mg/l; thiamine-HCl 0.1 mg/l; nicotinic-acid 0.5 mg/l; glycine 2 mg/l. The second stage is observed and the percentage of contaminant fungi. The observed contaminants character includes the colour, the direction of growth, and the hyphae colony's shape. Determination of contaminants type compared to the morphology of references. The result is the highest contamination in flower stalk explants, 81%; most colonies on leaf explants are 28. Contaminant fungi grow predominantly of fungi with white and grey colour and a rough surface shape. The macroscopic character of contaminant fungi in tissue cultures mostly comes from the class of Deuteromycetes and Zygomycetes.Keywords: Bromheadia finlaysoniana ,  contaminant, fungi, tissue cultur

Using Box–Behnken experimental design to optimize the degradation of Basic Blue 41 dye by Fenton reaction

Degradation of a Basic Blue 41 dye using Fenton reagent was examined at laboratory scale in batch experiments using Box-Behnken statistical experiment design. Dyestuff, hydrogen peroxide (H2O2) and ferrous ion (Fe2+) concentrations were selected as independent factors. On the other hand, color and chemical oxygen demand (COD) removal were considered as the response functions. The value of coefficient of determination (R-2) for both color and chemical oxygen demand removal with values 0.98 and 0.99 shows the best agreement between predicted value and experimental values. Perturbation plots indicated that iron dosage has the most effect on both color and COD removal. Normalized plot of residuals also indicated that the models were adequate to predict for both responses. Color and COD removal increased with increasing H2O2 and Fe2+ concentrations up to a certain level. High concentrations of H2O2 and Fe2+ did not result in better removal of color and COD due to hydroxyl radical being gradually consumed by both oxidant and catalyst. Percent color removal was higher than COD removal indicating the production of colorless compounds. The second-order polynomial model revealed optimal process factor ratio. The ratio of H2O2/Fe2+/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195 mg/L/90 mg/L/255 mg/L

Capacity-constrained renewable power generation development in light of storage cost uncertainty. ESRI Working Paper No. 647 December 2019

The development of sustainable energy sources and their enabling infrastructures are often met by public opposition, resulting in lengthy planning processes. One proposed means of reducing public opposition is constraining the capacity of renewable energy projects onshore, leading to more small-scale, decentralised and possibly community-driven developments. This work computes the effects of same by performing a medium- and long-term generation expansion planning exercise considering two renewable development cases, in which renewable power expansion is spatially constrained to certain degrees, under high and low storage cost regimes. We employ an appropriately designed optimisation model, accounting for network effects, which are largely neglected in previous studies. We apply our study to the future Irish power system under a range of demand and policy scenarios. Irrespective of storage costs, the unconstrained portfolio is marginally cheaper than the constrained one. However, there are substantial differences in the final generation expansion portfolios. The network reinforcement requirements are also greater under the unconstrained approach. Lower storage costs only slightly mitigate the costs of capacity constraints but significantly alter the spatial distribution of generation investments. The differential in costs between the unconstrained and constrained cases increases non-linearly with renewable generation targets