• Energy Research

Abstract This paper deals with a new method to calculate the higher heating value (HHV) of pyrolysis oils by using the analysis results of their gas chromatography–mass spectrometry or high-pressure liquid chromatography. This new method is called “GC–MS method” or “GCM”. The HHV which is calculated by this method is compared to the one given by the researchers (generally obtained by bomb calorimeter) on the one hand and those of Dulong’s and Vondracek’s formulae on the other hand. The results show that GCM and Vondracek are generally in a good agreement with the experimental values than those obtained with Dulong’s formula.

A new two-stage gasifier with fixed-bed has recently been installed on CIRAD facilities in Montpellier. The pyrolysis and the gasifier units are removable. In order to characterise the pyrolysis products before their gasification, experiments were carried out, for the first time onlywith the pyrolysis unit and this paper deals with the results obtained. The biomass used is Pinus pinaster. The parameters investigated are: temperature, residence time and biomass flow rate. It has been found that increasing temperature and residence time improve the cracking of tars, gas production and char quality (fixed carbon rate more than 90%, volatile matter rate less than 4%). The increase of biomass flow rate leads to a bad char quality. The efficiency of tar cracking, the quality and the heating value of the charcoal and the gases, indicate that: temperature between 650 °C and 750 °C, residence time of 30 min, biomass flow rate between 10 and 15 kg/h should be the most convenient experimental conditions to get better results from the experimental device and from the biomass pyrolysis process. The kinetic study of charcoal generation shows that the pyrolysis process, in experimental conditions, is a first-order reaction. The kinetic parameters calculated are comparable with those found by other researchers. (Resume d'auteur)

Abstract High heating value (HHV) is an important property which characterises the energy content of a fuel such as solid, liquid and gaseous fuels. The previous assertion is particularly important for vegetable oils and biodiesels fuels which are expected to replace fossil oils. Estimation of the HHV of vegetable oils and biodiesels by using their fatty acid composition is the aim of this paper. The comparison between the HHVs predicted by the method and those obtained experimentally gives an average bias error of −0.84% and an average absolute error of 1.71%. These values show the utility, the validity and the applicability of the method to vegetable oils and their derivatives.

To address the growing electricity demand driven by population growth and economic development while mitigating climate change, West and Central African countries are increasingly prioritizing renewable energy as part of their Nationally Determined Contributions (NDCs). This study evaluates the implications of climate change on renewable energy potential using ten downscaled and bias-adjusted CMIP6 models (CDFt method). Key climate variables—temperature, solar radiation, and wind speed—were analyzed and integrated into the Teal-WCA platform to aid in energy resource planning. Projected temperature increases of 0.5–2.7 °C (2040–2069) and 0.7–5.2 °C (2070–2099) relative to 1985–2014 underscore the need for strategies to manage the rising demand for cooling. Solar radiation reductions (~15 W/m2) may lower photovoltaic (PV) efficiency by 1–8.75%, particularly in high-emission scenarios, requiring a focus on system optimization and diversification. Conversely, wind speeds are expected to increase, especially in coastal regions, enhancing wind power potential by 12–50% across most countries and by 25–100% in coastal nations. These findings highlight the necessity of integrating climate-resilient energy policies that leverage wind energy growth while mitigating challenges posed by reduced solar radiation. By providing a nuanced understanding of the renewable energy potential under changing climatic conditions, this study offers actionable insights for sustainable energy planning in West and Central Africa.

Abstract Pyrolysis plays a major role in the optimization of process efficiency and gas quality in two-stage gasifiers. We developed an original reactor at pilot scale to investigate continuous fixed bed pyrolysis, in either allothermal or autothermal operating mode using air injection. Instrumentation and analysis enabled thermal profiles to be established inside the bed along with fine measurement of yields, char composition, permanent gases, and compounds at the outlet of the pyrolysis reactor. Under oxidative conditions, fixed-bed pyrolysis led to smoldering and the stabilization of an ignition front between 10 and 20 cm below the bed surface. With oxidative pyrolysis, yields of organic condensates were lower than with allothermal pyrolysis, whereas the production of pyrolysis water and permanent gases increased considerably. The main conclusion is that during autothermal pyrolysis in fixed-bed conditions, the presence of oxygen promotes oxidation of volatile matter and cracking reactions, thereby increasing the production of pyrolysis water and permanent gases. We observed a significant increase in yields of CO2 and CO, while the yield of char remained comparable to that in allothermal experiments.

Higher heating value (HHV) is an important property of a fuel, especially for vegetable oils, fats and their derivatives which are intended to replace petroleum fuels. There are lots of methods to evaluate the HHV of a fuel. In this paper, the HHV of vegetable oils, fats and their derivatives (biodiesels) is calculated by using the HHV of their pure fatty acids/methyl esters. The study reveals that, to be in a good agreement with the experimental values, the HHV of the neat compounds must be determined with the highest accuracy. With an error inferior to 2% by comparison to the experimental values, this work shows that the HHV of pure fatty acids or that of methyl esters can be judiciously used to calculate the HHV of the biofuels which they are the components.

The main objectives of this paper are firstly to investigate the behaviour of the thin layer drying of plantain banana, mango and cassava experimentally in a direct solar dryer and secondly to perform mathematical modelling by using thin layer drying models encountered in literature. The variation of the moisture content of the products studied and principal drying parameters are analysed. Seven statistical models, which are empirical or semi-empirical, are tested to validate the experimental data. A non-linear regression analysis using a statistical computer program is used to evaluate the constants of the models. The Henderson and Pabis drying model is found to be the most suitable for describing the solar drying curves of plantain banana, mango and cassava. The drying data of these products have been analysed to obtain the values of the effective diffusivity during the falling drying rate phase.

Abstract In this paper, we report the results of the study of the first model of solar photovoltaic refrigerator with three compartments: one for vaccine and medicines storage, the second one for the personal use of the medical staff, and the third one for water freezing. A cold storage is made around the evaporator in order to give the system several days of autonomy. The experimental study of the system has been made, as well as a dimensionment of the photovoltaic generator. The main results are the following: