Abstract: A solar energy collection system can include a plurality of heliostats configured to reflect sunlight to a target mounted on a tower. Each of the heliostats can include (i) a mirror assembly, which can include at least one mirror, at least one support arm and a pair of diagonals attached to each end of the support arm, the support arm attached to the backside of the mirror along its entire length, (ii) an elongated central support element, (iii) at least one connecting element configured to attach the mirror assembly to the elongated central support element. The location of attachment points on the at least one connecting element can define the curvature of the mirror in at least one dimension.

Abstract: A high capacity primary (single-use; non-rechargeable) battery pack for high current portable appliances such as cellular phones employs electrochemical cells that use ambient oxygen for one of the electrodes. The pack makes possible a simple low cost design by providing for oxygen supply in a completely passive yet compact configuration. Cells may be arranged inside a housing in a tightly packed arrangement by providing internal spaces that are sized to permit diffusion and, if possible, bulk air flow. The highest volumetric energy density is achievable by permitting bulk flow of air into the housing. It has been found that in practical use, in applications such as cellular telephones, that bulk air flow can play a significant role in gas exchange required for operation. A number of design criteria are developed for providing for a mix of molecular diffusion and bulk flow in the design of battery packs according to the invention.