Waste Geothermal Hot Water for Enhanced Outdoor Agricultural Production

Abstract

In Iceland there is a super abundance of waste hot water from geothermal power plants. Some of this is re-purposed (sequentially used) for district heating and heated swimming pools. This vast underused energy source can also enable the growth of out of zone plants, enhance agricultural production by 20% and extend the growing season. The authors have developed and field tested an energy intensive shallow system of bottom heat using the existing heated sidewalk materials. Tomatoes that do not survive outdoors in Iceland have produced ripe fruit. A zucchinis harvest was documented and the test banana plant was still alive in September after the first frost. These plants all died in the control garden which had the same piping system, and identical soil types and depths. Heat transfer data, infrared analysis and plant growth data were gathered to preliminarily document and quantify the system’s viability and market potentials.

Advanced Thermoelectric Materials for Energy Harvesting Applications

“…This can be achieved more precisely via creating proper material "nanostructuring" inducing a large number of interfaces and facilitating thus a phonon scattering resulting into low thermal conductivity values. The TE material's research and the promising nanostructuration approaches are part of the wider field of nanotechnology, where key elements are the long-range ordering with controlled nanostructures for enhanced optical [21][22][23][24][25][26][27][28][29], electrical [30][31][32][33][34][35][36][37][38][39], mechanical [40][41][42] and magnetic [43,44] properties. Figure 3 demonstrates the number of publications on TE materials from 1965 to today, highlighting the slight increase of TE research rate from 1965 to 1993 and the rapid increase from that year to now, due to the flagship stimulating work of Dresselhaus (data collected from Science Direct data library using "thermoelectric" as the keyword).…”

“…The authors have developed an intensive open-field heat agriculture system using geothermal steam and steam condensate that extends growing seasons and enables the cultivation of out-of-region, non-native crops [31,32]. It has an underground piping system in Iceland that is similar to the method for heating sidewalks and how waste heat from combined heat and power (CHP) systems warm green roofs [33].…”

Geothermal Energy for PICTs

“…Most geothermal power stations are large, costly, and can sometimes function as a nucleus for large subsidiary industries based around waste heat from the power plant. Pioneering installations in Iceland and New Zealand provide testimony of the economic and environmental success of subsidiary industries, displaying a plethora of waste heat uses including timber drying, food drying, aquaculture, greenhouses, and thermal spas (Dell et al 2013;Kelly 2011).…”

An Assessment of the Sustainability of Lignocellulosic Bioethanol Production from Wastes in Iceland

“…This situation means that grasses turn green and tillage can be performed, but little else is grown [9,11]. Based on these conditions, biofuel production efforts in Iceland should focus on MOW as part of the second-generation biomasses.…”

“…Thus, the only products that can be developed must have a growing time within this period and the temperature required for growth must be compatible with the environment temperature (5-7 • C). This situation means that grasses turn green and tillage can be performed, but little else is grown [9,11].…”