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This paper aims to explore the feasibility of establishing self-sufficient electricity generation systems in off-grid remote communities using renewable energy sources. It provides an overview of current trends and developments in Renewable Energy Communities worldwide, with a focus on remote locations. To assess the technical feasibility, simulations were conducted using PVGIS for irradiation data and a load generator for energy consumption data. Different scenarios combining photovoltaic modules with lithium-ion battery systems were simulated using a dedicated optimization model developed in the PYTHON environment. The simulations aimed to size the entire system for three distinct locations: Congo, Australia, and Canada. The optimal number of PV modules determined for each location was 50 for Congo and 55 for Australia, and the battery system sizes were found to be 225 kWh and 150 kWh, respectively, admitting usual practices for the energy not supplied. The results obtained regarding Canada pointed to a system difficult to justify from an economic standpoint due to challenging weather conditions, namely, the existence of several consecutive days without irradiation.

The freshwater microalga Haematococcus pluvialis is well known as the cell factory for natural astaxanthin, which composes up to 4–7% of its total dry weight. The bioaccumulation of astaxanthin in H. pluvialis cysts seems to be a very complex process that depends on different stress conditions during its cultivation. The red cysts of H. pluvialis develop thick and rigid cell walls under stress growing conditions. Thus, the biomolecule extraction requires general cell disruption technologies to reach a high recovery rate. This short review provides an analysis of the different steps in H. pluvialis’s up and downstream processing including cultivation and harvesting of biomass, cell disruption, extraction and purification techniques. Useful information on the structure of H. pluvialis’s cells, biomolecular composition and properties and the bioactivity of astaxanthin is collected. Special emphasis is given to the recent progress in application of different electrotechnologies during the growth stages and for assistance of the recovery of different biomolecules from H. pluvialis.

Hydrogen and carbon dioxide fermentation to methane, called bio-methanation, is a promising way to provide renewable and easy-to-store energy. The main challenge of bio-methanation is the low gas-to-liquid transfer of hydrogen. Gas injection through a porous membrane can be used to obtain microbubbles and high gas-to-liquid transfer. However, the understanding of bubble formation using a membrane in the fermentation broth is still missing. This study focused on the impact of liquid pressure and flow rate in the membrane, gas flow rate, membrane hydrophobicity, surface, and pore size on the overall gas-to-liquid mass transfer coefficient (KLa) for hydrogen with gas injection through a porous membrane in real fermentation conditions. It has been shown that KLa increased by 13% with an increase in liquid pressure from 0.5 bar to 1.5 bar. The use of a hydrophilic membrane increased the KLa by 17% compared to the hydrophobic membrane. The membrane with a pore size of 0.1 µm produced a higher KLa value compared to 50 and 300 kDa. The liquid crossflow velocity did not impact the KLa in the studied range.