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This paper presents the results of a comparative economic analysis of residential solar photovoltaic systems throughout the provinces of Canada in 2013 and 2016. The study was conducted using the discounted cash flow method. Basic economic theory involving the concepts of net present value, payback period, and internal rate of return was used, based on data from 2013 and 2016. The solar photovoltaic market is dependent on supporting policies and incentives. Thus, the relevant federal and provincial supporting policies for building implementation are briefly described and considered in the calculations. Results are presented in the form of summary tables showing selected major cities, classified into different categories, in terms of financial viability. The results show that in 2013 there were 9 cities out of 13 for which the payback period was expected to be higher than 30 years but in 2016, only Montreal PV projects remain infeasible. Furthermore, sensitivity analyses were conducted to establish new values for the selling price of electricity, initial cost of the proposed project, and percentage of subsidy required to ensure project attractiveness, that is, a short payback period of only 5 years for residential buildings.

In the north of Québec (Canada), off-grid aboriginal communities rely on diesel for both space heating and electricity production. Renewable alternatives are therefore necessary to reduce the impact of burning diesel in a region with strong population growth and increasing energy needs. The main challenges are the subarctic environment (more than 8000 heating degree days), the presence of permafrost and the lack of local expertise on drilling and installation of borehole heat exchangers.The communities of Kuujjuaq (58 °N) and Whapmagoostui-Kuujjuarapik (W-K, 55 °N) were chosen as case studies to evaluate the shallow geothermal potential and predict the long-term behaviour of ground source heat pumps (GSHP) and underground thermal energy storage systems (UTES). Local geology mainly consists of low permeable and thermally conductive crystalline bedrock (thermal conductivity of 2-4 W/mK) underlying highly permeable, frost-susceptible and poorly conductive marine sediments (thermal conductivity of 1-1.5 W/mK), generally not thicker than 30-40 m. Electrical resistivity tomography and ground penetrating radar surveys have been carried out to locally evaluate the presence of ice-rich ground that strongly depends on the local hydrogeological conditions. Average underground temperature in the first 100 m is around 1 °C in Kuujjuaq and 2 °C in W-K. Geothermal gradient and heat flux were estimated to be on average 15 °C/km and 40 mW/m2, respectively.Results of the studies carried out in these villages show that both GSHP and UTES are viable technologies to replace part of the current diesel consumption of residential buildings and drinking water facilities, with 10% to 50% primary energy saving depending on the technology. Fifty years’ life-cycle cost analyses demonstrated that the levelized cost of energy for GSHP and UTES is as low as 0.10 and 0.19 USD$/kWh, respectively, compared to the business-as-usual scenario standing at 0.21 USD$/kWh. It also turned out that the energy and drilling costs are key obstacles to a widespread deployment of these technologies in the North. A cost of 110 USD$/m has been defined as a threshold for getting interesting paybacks on the initial financial investment. UTES is also a valuable technology aiming to extend the growing season of community greenhouses in place in both Kuujjuaq and W-K. In Kuujjuaq, a coupled daily and seasonal heat storage is under study to provide renewable heat and help increase the food security in Nunavik.Future activities aim at the set-up of a first demonstration plant to be tested in a subarctic environment with underground close to permafrost conditions. A 200-m well will be drilled in 2020 in W-K and the installation of a borehole heat exchanger will be showcased for technological transfer. Conventional thermal response tests (TRT) and a novel approach of oscillatory TRT will also be carried out to evaluate the in-situ thermal conductivity and heat capacity.

Phase change materials (PCM) used in thermal energy storage systems present high storage capacity and require low temperature variation to allow effective heat charge or discharge density. However, these materials involve too low thermal conductivities ( −1 K −1 ) which can limit the heat transfer power between the heat transfer fluid and the phase change zone. In the first part of this study, high power level composites made of PCM (organic and also inorganic) and graphite have been elaborated in the thermal range from 50 to 350 °C in order to increase the effective thermal conductivity. In a second part, the assessment of their use as solar absorbers has been realized. Results show that these composites present high absorptance with respect to the whole solar radiation spectra. This allows new potentiality of integration of such materials in solar thermal processes offering a direct management of heat variation at the very first step of the process.

The use of phase change materials (PCMs) to increase solar domestic hot water (SDHW) system efficiency has been already studied by different ways. Some studies place the storage material in the water tank, others directly in the solar thermal collector. However both of them show that the effectiveness of such a use is not relevant. This paper is devoted to a new approach: the PCM is placed in the heat transfer fluid solar loop from the SDHW system. This configuration is studied under different weather conditions and system parameters. On the contrary to previous results, this parametric study highlights a significant increase of the system efficiency due to the PCM. Then, a genetic algorithm allows proposing an optimized system configuration.

Thermal energy storage is now a key parameter to overcome the delay between energy supply and demand in many applications. To address this issue, the use of phase change materials (PCM) tends to be more and more common. Given the attempted objectives of such applications, performances of the PCM are a cornerstone of the whole system. Therefore, a correct determination of their intrinsic properties is crucial. To perform this step, one may use a calorimetry experiment. Unfortunately, the interpretation of the thermogram is not straightforward and consequently, when not feasible at all, estimations may be wrong. As an example, pure substance as sometimes said to melt at a non-uniform temperature (their enthalpy being smeared over several degrees), and binary solutions are associated with liquidus temperature and latent heat that do not match the correct form of their enthalpy. The present work proposes a new method to avoid such issues. To summarize the novelty of our approach, the main idea is to use an inverse method to identify the thermodynamical parameters of the sample through a matching step between the experimental curves and theoretical ones. It means that contrary to many others methods, we do not directly extrapolate the thermodynamical properties ( e.g. the enthalpy) from the thermogram. Instead, we suppose an a priori formulation of the enthalpy, based on thermodynamical principles. Thus the thermodynamical parameters are inputs of which only values are computed from the experiments. Capabilities of the method are shown on pure substances and binary solutions examples.

The overall objective of this work is to evaluate the potential of compressed expanded natural graphite (CENG) and phase change material (PCM) composites to improve the performance of solar domestic hot water (SDHW) systems. To achieve this target, an original approach has been chosen. Comparatively to other studies, in which the storage material is usually placed on top of the water tank, the proposed approach was to place the composite directly inside a flat plate solar collector in substitution to the traditional copper-based solar absorber. In a previous paper ( Haillot et al., 2011 ), elaboration and characterization of various composites led to the selection of three relevant composites suitable to their integration into a solar thermal collector. The present paper is devoted to the analysis of such a system to evaluate its actual performance. To reach this objective, a numerical model is proposed and its reliability validated by mean of corresponding experimental data. Despite the fact that under summer meteorological conditions the performed simulation highlights an increase of the system efficiency by adding a composite to the solar collector, the cumulative annual performance of such a system is penalized by low efficiency during winter time. However, the obtained simulated results allow us to offer a perspective of work that would maximize the benefits of adding storage composite to a SDHW system.

This work aims to evaluate the performance of a solar domestic hot water (SDHW) system including a latent storage material. The originality of our approach consists to place a composite made of compressed expanded natural graphite (CENG) and phase change material (PCM) directly inside a flat plate solar collector in order to replace the traditional copper-based solar absorber. According to this target, the study is composed of two steps: the composites preparation and characterization; and the analysis of the system to achieve optimal integration of the material in the process. The present paper is focused on the selection of the most promising composite to implement in the solar collector. In order to reach this objective, several composites based on CENG and various storage materials (paraffin, stearic acid, sodium acetate trihydrate and pentaglycerin) have been elaborated and characterized. The synthesis of all these measurements allowed us to select three composites whose characteristics match their integration into a solar thermal collector.

Latent heat storage systems, using phase change materials (PCMs), present the advantage of a high storage density at nearly constant temperature. They offer intrinsic advantages for heat storage in combination with steam as heat transfer fluid. Important applications of these storage systems are the areas of solar industrial process heat supply and heat recovery in industrial batch processes. The presented work aims to identify the most suitable PCMs, according to the studied temperature range (120–150 °C) and is based both on literature review and thermal analysis measurements. The thermal behaviour of eleven potential storage materials was studied by means of thermogravimetry (TG) and differential scanning calorimetry analysis (DSC), coupled with a quadrupole mass spectrometer (QMS). The paper emphasizes the importance of the measurement conditions on the results. In particular the impacts of the type of crucible (open/closed), the atmosphere (N2, N2/O2) and the cycling stability are presented.

Composite materials based on expanded natural graphite (CENG) and various phase change materials (PCM) have been developed for low temperature solar applications (323–373 K). The integration of such composite materials directly into the solar collector could allow new storage functionality. A numerical model has been developed to describe the materials behaviour. Composites properties are presented and discussed.

International audience; Originally applied to fields related to oil and gas production and flow assurance, high pressure differential scanning calorimetry (HP-DSC) has now been involved in several new studies such as carbon dioxide sequestration by CO2/CH4 exchange in naturally occurring gas hydrates or CO2 hydrate reversible formation/dissociation for refrigeration loops. However, the technique still has some limitations, which are linked to the fact that the gas hydrate formation occurs at the gas/liquid interface, and because the hydrate nucleation can be rather difficult in small volumes especially in quiescent conditions. It leads to several problems such as inefficient gas dissolution, long induction times, formation of a hydrate crust covering the gas/liquid interface, low hydrate to water conversion, etc. As a result, it is very difficult to determine accurately the heat capacities and the kinetics of formation/dissociation of several systems involving gas hydrates. This study presents two prototypes of calorimetric cells equipped with an in-situ mechanical agitation system, which allow performing experiments under pressure (150 bar maximum for the cells used in this work). The first system presented, called MIXCEL®, was developed for macro-calorimetry analysis (experiments carried out with a BT 2.15 Calvet Calorimeter from SETARAM Instrumentation). Very recently, we have developed a novel prototype of micro-calorimetric agitated cell (called MICROMIXCEL®) for microDSC analyses (experiments carried out using a microDSC7 evo from SETARAM Instrumentation). Both technical aspects, and results obtained at macro and micro scales with gas hydrate systems are presented and discussed.

International audience; Les hydrates de gaz sont des composés cristallins qui se forment sous certaines conditions (généralement sous haute pression et basse température), lorsque des molécules d'eau sont en contact avec de petites molécules de gaz. Lors de leur formation, l'eau (molécule hôte) forme alors un réseau constitué de plusieurs cages, dans lesquelles sont piégées les molécules de gaz (molécules invitées) comme par exemple le méthane, l'éthane ou le propane, mais également les gaz acides à savoir le dioxyde de carbone ou le sulfure d'hydrogène. Ce type de structure aux propriétés intéressantes présente un large spectre d'applications pratiques, en particulier pour le captage, le transport et le stockage du CO2. Certaines propriétés thermodynamiques de ces hydrates de gaz (comme par exemple les données d'équilibre de phase, les enthalpies de formation, les chaleurs spécifiques, etc.), dont la connaissance est indispensable pour les applications visées, peuvent être obtenues par calorimétrie. En revanche, un des inconvénients majeurs des cellules calorimétriques sous pression actuellement sur le marché, est leur absence d'agitation, ce qui peut s'avérer problématique dans certains cas (solubilité du CO2 contrôlée par la diffusion, problème de métastabilité à la cristallisation, etc). Dans un premier temps, ce travail consiste à présenter les détails techniques d'un nouveau prototype de cellule calorimétrique récemment breveté, agitée mécaniquement, fonctionnant sous pression, et compatible avec le calorimètre BT 2.15 de la société Setaram. Dans un second temps, les potentialités de ce nouveau dispositif sont évaluées pour l'hydrate de CO2 en termes de temps d'induction à la cristallisation (avec/sans agitation et comparaison avec la micro HP-DSC), et de données d'équilibre de phase.