The AAD generates solar power in a number of different situations, including powering VHF radio repeaters, remote radio installations, automatic weather stations and in remote area power supplies, which harness both wind and solar energies for use in remote field locations.
VHF repeaters and remote radio installations
The AAD has deployed a number of repeaters in Antarctica and on Macquarie Island over the years in different locations for use by scientific and operational programs. VHF repeaters extend communications coverage around the stations for hand held and vehicle radios. Coverage may be extended up to 100 km depending on the line of sight.
Almost the whole of the Vestfold Hills region around Davis, for example, has VHF coverage. The VHF repeater on Tarbuck Crag makes it easy for expeditioners in the field to maintain communication with Davis with just a small hand held radio.
At some of the repeater sites, energy is generated by a combination of wind and solar power. However, as most repeaters are placed in remote locations on hills and mountain tops subject to extreme wind conditions (and hence damage), there is a greater reliance on solar power.
The winds at Macquarie Island do vary in direction and may reach considerable strength. Experience has shown that many wind generators will not survive the conditions present at the top of the mountains of Macquarie Island so we only use solar power to recharge the batteries. Measures are taken to ensure that the repeaters consume minimal power, thus extending battery capabilities. These include selection of radios for their low power consumption; fitting repeaters with a 'sleep mode' that switches off certain parts of the circuitry in the event of the repeater not being used for a set period of time, then 'wakes up' the circuitry when a signal is detected; and selection of regulators that disconnect the load when the battery voltage drops to a set level, thus preventing the battery from completely discharging.
Where wind generators are used, they are generally bolted to the top of cut-down 200 litre drums or mounted on a mast. The wind at each of the repeater sites tends to blow predominantly from a single direction and, hence, the generator does not need to swivel with changes in wind direction. The blades of the generator are shortened so as to increase survivability during periods of intense wind. Batteries are installed in insulated containers in order to minimise reduction in capacity due to cold.
The Tarbuck repeater shown in the photographs is powered both by a small wind generator and solar panels. The fibreglass housing for the solar panels was purpose designed by AAD engineers, and is known as a 'Tardis' box.
Remote Area Power Supply (RAPS) unit
The Remote Area Power Supply units (RAPS), came into being following a safety and environment audit. The report dealt with the condition of the Macquarie field hut electrics, and the methods used for storing of flammable liquids (ie petrol).
The first two modules were installed during the 2000-01 summer at Bauer Bay and Green Gorge, and three more were later installed at the Brothers Point, Hurd Point and Waterfall Bay field huts in 2001-02.
The 'remote area power systems' can generate power from three sources - petrol, sun and wind - and store it in batteries. They feature self-contained weatherproof accommodation, external to the huts, for all power needs.
The RAPS units can easily be transported by helicopters when necessary. An identical unit is kept at the station for training and spares. Installation is easy: they are levelled using adjustable feet, tied down with guys, the mast is raised and cables rolled out to the hut. Maintenance and access are straightforward, with all parts consistent between installations and careful attention to corrosion proof fastenings.
The modules incorporate batteries, petrol generator, fuel storage, refuelling pumps, solar panel, wind generator using a collapsible mast, instrumentation for monitoring battery condition and charging, full electrical protection, and capacity to drop out to protect battery cells from excessive discharge.
The RAPS units solve many of the occupational health and safety issues raised in the audit, and have been designed to minimise and contain any accidental fuel spills which may occur in the sensitive environment of Macquarie Island.