The proposed project is a combination of a new, crosssectoral technology of energy transfer and integrated building design. The main aim is to increase the viability and potential cost reduction for large scale solar heating and cooling with combined water treatment.
Advanced energy transfer
Compared with conventional thermal collectors, cost reductions can be achieved by using condensation aided heat transfer outside of the collector on a central, cheap plastic heat exchanger inside of a cooling-/heating-tower, that can also be used at reverse modus for space heating. A huge exchanger-surface allows the use of low input heating temperatures (up to 5-10K), leading to the use of an extended accumulation amplitude and, by this more efficient storage capacity.
Double/Triple use of solar input
The use of evaporation and condensation as a short time energy-storing effect induces delayed, cascade-like temperature growth. By this, the low-temperate part of the collector surface can be replaced by greenhouses, allowing double use of the surface for additional agricultural use. Additional profitability: 30-40%, in moderate/cold climate by using waste heat from a building: 20%, by additional use of composting waste heat: 60%. A third synergism of the process is given by the integration of water-treatment applications: Water condensation can be used for irrigationwater recycling from greenhouses and for seawater desalination from further evaporators in the collector without additional energy demand.
In context of fading water ressources, water re-use and seawater desalination will lead to an enormous additional energy demand, especially in the agricultural sector. Coupled with plant production, irrigation water recycling and waste-water treatment inside of an integrated system, solar desalination is able to become competitive with other decentralised (secure) systems.
Day-night thermal balancing
Greenhouses can be chilled during the hot summer season and heated during winter to expand vegetation period and increase plant productivity. This is only done infrequently because of high energy costs. By using day-night thermal balancing through the proposed system, primary energy can be reduced significantly. Seasonal extension of production becomes valuable by lowered running costs.
Due to cost reduction in modern, southern European house building, thermal mass of buildings is commonly reduced and substituted by air-conditioning, thus leading to high energy costs for cooling and often – compared with traditional building structures – to a reduction of comfort. Climate control by natural buoyancy, induced by the interior shape of PT2, combined with thermal balancing via day/ night thermal accumulation can replace conventional air conditioning. By this, space cooling can be performed at significantly reduced demand of primary energy, even at the use of light construction materials.
Seasonal balancing, building heat supply
The costs for a combination of solar collectors and central heating by using one unique heat exchanger can be lowered, thus enlarging the competitiveness of solar thermal applications.
Seasonal balancing, greenhouse heating
Energy is a main cost factor in greenhouse horticulture for central and northern Europe. Seasonal energy accumulation as a possible solution for the future is quite expensive. As the required temperatures in the greenhouse are lower than in buildings, it’s obvious to share accumulators with building heating systems to take advantage of a maximum storage temperature amplitude. A combination of enhanced cover isolation, seasonal accumulation, coupling with building heating system and the use of waste heat from composting is scheduled.
Reduction of building material
By using thermal accumulation, light constructions can be developed more radically, since the thermal mass of the building material can be completely substituted by the storage medium. By using durable and light ETFE-membranes for greenhouse- and solar collector covering, material consumption can be radically minimised. Energy demand and waste generation induced by building materials can be reduced.
Total economical viability
The project contains a study on future applications for the existing urban and sub-urban context, including a comparing study of the system’s economical viability. The emphasis will be onto an extended definition of urban energy demand, including energy content of basic investments (building and infrastructure materials) and basic consumables (water, food, material-/transport-losses.