This article aims to define the category of energy colonialism in order to analyse the conflicts that are arising due to the deployment of renewable energy megaprojects in the Global South and in the peripheries of the Global North. First, the limits of the corporate energy transition are questioned, and based on an exhaustive bibliographic review, the category of energy colonialism is formulated along with six dimensions that characterise it: geopolitical; economic and financial inequalities; power, violence, and decision making; land grabbing and dispossession; impacts on territories and commons; resistance and socio-territorial conflicts. Based on this framework, we analyse and juxtapose different expressions of energy colonialism in four case studies; the isthmus of Tehuantepec (Oaxaca, Mexico), the territories of Western Sahara occupied by Morocco, the Saami territory in Norway, and the rural territories of Spain. The results from this study allow us to conclude that energy colonialism is a useful concept for understanding and critiquing the effects of the corporate energy transition and establishing a base for grassroots and decolonial alternatives in both the Global North and South.

Nowadays, there is a wide scientific consensus about the unsustainability of the current energy system and at the same time, social awareness about climate change and the IPCC’s goals is increasing in Europe. Amongst the different pathways towards them, one alternative is the radical transition to a democratic low-carbon energy system where the local scale has a key leading role. Under this scope, this research is framed within the mPOWER project, financed by the European Commission’s H2020 programme, which promotes collaboration among different European municipalities in order to boost the transition to a renewable-based participatory energy system. This paper presents the starting point of the mPOWER project, where the main energy features of 27 selected European municipalities are collected and analysed for the year 2016. An open public tender and selection process was carried out among European cities in order to choose the candidates to participate in mPOWER project. A view of this situation will be taken by the mPOWER project as a diagnostic baseline for the following steps: a peer-to-peer knowledge-sharing process among these European municipalities, and subsequently, among a more extensive group. The first finding of the paper is that, even if those municipalities are trying to reduce their greenhouse gas emissions, they are highly dependent on fossil fuels, even in cases where renewable energies have significant presence. Second, their energy consumption is logarithmically related to the human development index and gross domestic product but not to the size of the cities and their climate characteristics. Finally, despite the work that these cities are making towards energy transition in general and within the mPOWER project in particular, the paper shows a high difficulty mapping their energy systems. The lack of accurate and unified data by the municipalities is a sign of disempowerment at a local and public level in the energy sphere and makes difficult any strategy to advance towards a bottom-up energy transition. Among other goals, the mPOWER project aims to reveal these kinds of difficulties and help local authorities in managing their transition paths.

One of the key factors that currently limits the commercial deployment of thermal energy storage (TES) systems is their complex design procedure, especially in the case of latent heat TES systems. Design procedures should address both the specificities of the TES system under consideration and those of the application to be integrated within. This article presents a fast and easy to apply methodology for the selection of the design of TES systems suitable for both direct and indirect contact sensible and latent TES. The methodology is divided into four steps covering: (a) description of the thermal process or application, (b) definition of the specifications to be met by the TES system, (c) characterization of the specific TES system under consideration and (d) the determination of the TES design. This methodology needs as major inputs the operation conditions of the energy system where the TES system will be integrated, that is, temperatures and mass‐flow; as well as the charging and discharging time performed by the TES system under different conditions. The latter can be generally deduced from the Fourier number, which can be obtained both theoretically (ie, by simulation) or empirically from the analysis of the TES technology under consideration. The methodology is then applied to a 10 kW residential cogeneration application considering two TES technologies. One consists of a direct‐contact hot water storage tank and the other, of an indirect‐contact plate‐based latent heat TES system developed by the authors. The resulting volume needs for the hot water storage tank is approximately twice the volume of the latent heat TES system, respectively, 5.97 and 2.96 m³. The presented methodology eases the design process of TES systems and decreases the amount of time needed to size them from days/hours to minutes.

The development of a prototype linear solar collector Type Fresnel, has a purpose the use of direct solar heat radiation for water heating and/or steam production, as an alternative to supply conventional water heating systems or steam generators, which consume energy from fossil fuels. For the development of the system, used the solar radiation of the UTS, located in Bucaramanga, Colombia, is identify the mathematical models to perform the sizing, then materials based on technical specifications and availability in Colombia, in order to perform the assembly and field tests, measuring the ambient and in the collector temperature to determine the efficiency of the model. It should be noted that, the model presented does not have a control system for flow, temperature, pressure and level, it has no solar tracking of any kind; Its movement was done manually with each reflex. Finally, the model does not have a hydraulic system forced, and has a preheater at the entry of the concentration point.