The Australian Defence Force (ADF) can't afford to spend too much building many such systems. I suggest one "sweet-spot" is for deployable, shipping container sized modules (as used for the US Air Force system). A shipping container sized module can be built in a factory and transported to a military base and set up to operate. When needed, it can be packed up and shipped to a bare base to supply power. Shipping containers can be transported by civilian trucks, trains and ships, as well as military helicopters and fixed wing aircraft.
As a target size I suggest an ISO 20 Foot Shipping container. This is large enough that commercial off the shelf power systems can be used, but small enough to be moved easily. The industry standard for a shipping container allows 30,400 kg maximum
gross weight. However, the RAAF's larget helicopter, the Boeing CH-47 Chinook, can only carry 12,700 kg, allowing for 10,500 kg of equipment in the container. The weight is unlikely to be the limiting factor, as while diesel generators are heavy, solar panels are not.
The USAF containerized power supply requires three containers and considerable setup. This is not ideal for deployment on a military operation, where speed is of the essence and there is limited skilled labor available. I proposed the Australia unit should be usable with one container (but expandable with multiple units). It should be able to be assembled, or disassembled, by one technician who has received three hours of familiarization, supervising four military personnel who have received no special training, in six hours. There should be no tools or additional equipment required, apart from what comes in the container.
Container ContentsThe container would have mounted in it a conventional diesel generator, power regulating electronics and a fuel tank (for seven days supply). There would also be space for solar panels, the framework to mount them, cables, tools and manuals.
A container has a volume of 33.1 m³. Assume a design which provides a conventional diesel generator and 20% solar power (a cost effective combination) and seven days fuel supply (on diesel alone). It is then necessary to calculator what capacity system would fir in the container.
Solar PanelsThe Sharp NU-A188EY solar panel has a typical output of 188W and is 1328 x 994 x 57.5mm and weighs 16.5kg. Assuming an adjustable stand (which doubles as a cradle in the shipping container) and cables for this doubles the volume and adds 25% to the weight of the panel, this makes volume of 0.15 m³, or 0.807 m³/kw and 110 kg/kw. Assuming the entire container was filled with these panels, there is room for 220, providing 41kw. However, there has to be room for a generator and fuel.
Generator and FuelA typical generator set (CAT 300 kVA : 3406C) is 4.3 x 1.1 x 2.2 m,10.2 m³, or 0.034 m³/kw. It weighs 3,454 kg or 12 kg/kw. The fuel required, running at 50% power is 38.5 l/hr. Assume the solar panels replace 25% of the fuel, reducing consumption to 29 l/hr, or 4.9 kl per week, or 0.016 m³/kw and 163 kg/kw (allowing for tank).
Calculating Capacity of a Containerized System
|Volume ISO m³||33.1|
|% total capacity||86%|
|Total weight kg||12745|
|CH47 Capacity kg||12700|
|% total capacity||100%|
So allowing for solar panels, generator and one week's fuel, a shipping container could hold a 37 kw power supply. The capacity of the container would be limited by weight, rather than volume.
However, the ADF already has diesel generators. So a simpler alternative energy supply would be one purely solar powered. This would remove the safety issues around transporting liquid fuels. An ISO container could hold a 41 kw solar array, which could then be linked to one or more diesel generators.
CostAssuming $2,000 per kw for solar panels, mounting hardware and cables. A diesel generator costs about $300 per kw. Allowing for the cost of the container and construction, the cost would be about $200,000 per unit.
|Total per kw||$2,327.00|
|Total for module||$86,099.00|
Number of ContainersA reasonable deployable solar capacity for the ADF to aim for would be 200 shipping container sized modules, producing 7.4 MW, at a cost of $40M. That might sound like a lot of shipping containers and money, but they would all fit in the Navy's two LHD ships, now under construction at a cost of $2B.
Smaller Containers and ModulesAdvanced Power's 16 kVA, APD016. Also for maximum flexibility, the equipment should not be permanently mounted in the container. The container could have minimum modifications from a standard unit, with a generator and fuel tank which can be removed for separate use. The PV panels which could be in packs which can be carried out by two personnel and set up by hand, with no lifting equipment required.
PV Panels to Supplement Small GeneratorsAdvanced Power's 1.3 kW APD1300, or four with the 2.5 kVA, APD2500. These configurations would be small enough to be transported by the Light Cargo Trailer of a Mercedes-Benz G-Wagon and a medium utility helicopter.
Normally connecting a PV array to a generator is a complex process requiring a trained technician. Instead the modules could be fitted with their own electronics and a simple plug and socket to connect in between the generator and the load. There would be no need for any controls on the PV panel: it would be simply plugged in and supplement power from the generator, lowering fuel use and providing a constant voltage for sensitive systems.