| Title | Daily and Seasonal Heat Storage for Greenhouse Food Production in Nunavik (Canadian Arctic) |
|---|---|
| Authors | Nicolò GIORDANO, Paul PICHE, Stephane GIBOUT, Didier HAILLOT, Cedric ARRABIE, Annie LAMALICE, Daniel ROUSSE, Xavier PY, Félix-Antoine Comeau, Jasmin RAYMOND |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | daily heat storage, seasonal underground heat storage, greenhouse, food, Nunavik |
| Abstract | Energy and nutrition are two of the main challenges for autochthonous people in the Canadian arctic territories. In Nunavik (northern Québec), Inuit people live in remote off-grid communities and diesel is the main source of energy providing both heating and electricity. Owing to global changes, traditional food such as wild fish, animals and berries are becoming more and more difficult to get, and imported food carried by boat and air more expensive. To date, 62 % of the Inuit families suffer from food insecurity and the development of means of local food production are critical for their future. Few community greenhouse projects have been developed in the last 20 years in different Nunavik villages, but none of them has heating systems and the production is therefore limited to a growing season that last about 4 months each year. This research activity aims at evaluating the potential of renewable energy systems for greenhouse production in Kuujjuaq, the capital and most populated village in Nunavik. In 2016, the community greenhouse in town has been instrumented with temperature, humidity and solar radiation sensors. Monitoring data have shown a significant day/night temperature difference that prevents optimal plant growing. To partially reduce daily temperature changes, in the fall 2018 a bed of pebbles with known thermal properties has been placed underneath the plants’ soil to provide a daily heat storage medium. A controlled air circulation system transfers heat to the pebbles during the day and backwards during night-time. The first results show that the system is reliable and can guarantee an efficiency of 3, with 40-50 kWh of solar heat that would otherwise be lost through air ventilation. Horizontal and vertical underground seasonal storage systems were additionally simulated to evaluate the possibility of extending the production season currently ending in September. Even though the ground hosting the horizontal system shows lower thermal properties than the deeper saturated sediments, the horizontal storage option can guarantee better performance in terms of available energy, with 13 MWh of energy transferred to the greenhouse from October to December and 57 % of heat recovery. Nevertheless, the system should be better optimized in order to provide a higher and more stable temperature of the fluid circulating into the heating system. In conclusion, coupling daily and seasonal storage technologies can be an interesting and cost-effective option to provide renewable heat to northern greenhouses in order to both anticipate and extend the growing season by at least 2-3 weeks. |