The authors expect that the future will bring

• Limited resources of natural gas

• Increased demand for biomass to gas and liquids for the transport sector

• Increased windmill capacity (+photovoltaic and wavepower)

• Increased demand for electricity regulation

That means that heat production mainly has to come from renewable energy (not biomass) and “waste” heat from electricity regulation.

The most efficient systems to solve these problems are district heating systems. So a main part of the solution of the above mentioned problems will be

Solar Thermal systems have only recently become popular in the UK. Research shows that in the year 2000 only 151,000 m2 of water collectors (both flat plate and evacuated tube) were in operation in the UK [1]. This equates to <3 m2 of collector area per 1,000 inhabitants, which is significantly lower than countries like Greece (264 m2), Austria (198 m2), Denmark (46 m2), Switzerland (37 m2) and Germany (34 m2). There is a false impression, shared even amongst architects and designers, that there is insufficient solar energy in the UK to achieve solar fractions which would contribute significant energy savings and carbon reductions. This paper shows the solar thermal potential for Wales. Twelve house types, considered as representative of the entire Welsh Housing stock are modelled and the thermal energy demands for space heating, cooling and domestic hot water preparation for each house type are predicted. The share of the total thermal energy requirement that can be met by solar energy, instantaneously and by means of thermal energy storage techniques for each house type is analysed.

[1] Introduction

Solar pond is a simple and low cost solar energy system which collects solar radiation and stores it as thermal energy in the same medium for a long period of time. When solar radiation penetrates on the solar pond surface, the infrared — radiation component will be firstly absorbed rapidly in the surface mixed layer. However heat loses to the atmosphere by convection and radiation. The remaining radiation will subsequently be absorbed party in the non — convective zone before the last of the radiation reaches the bottom of the pond. The saline concentration in this layer is higher than the others. The more obvious application for solar ponds are for heating and cooling of buildings, power production and desalination.

The first recorded solar pond to a natural solar lake was that of Kalecsinsky who decribed the Lake Madoc (Medie Lagoon), located at (42 ° 44’N,28 ° 4 5’E ) in Transylvania This lake showed

[3] Conclusion

Composite material based on CENG and PCM has been directly implemented behind a solar absorber. The insertion of this composite provides new storage functionality to the collector. A MUE of 0.26 has been found and considering the efficiency of the solar absorber, 67 to 89% of the solar energy collected has been stored. The high conductivity of the storage composite gives rise to a high level of power restitution of the stored energy.

A numerical model had been developed for charge and discharge processes. Comparison between experimental and simulated temperature profile allowed us to validate this model.

Nomenclature

Table 1. Nomenclature, greek symbols and superscripts.

Nomenclature

A Area (m2) Cp Calorific capacity (J. kg-1.K-1)

[5] Introduction

[6] Description of the Alstonvale Net Zero House