We've been pleasantly surprised to find that the diesel generator now needs to run for only 7 to 8 hours per day. This compares to 24 hours per day previously, and to 12 hours per day if the system saved 50% as predicted. Now we have silent, emissions-free power for 16 to 17 hours per day from direct solar input or from power stored in batteries. And this is at a time when our power needs are high because the station is fully occupied, and during a period that has been quite cloudy. We couldn't be happier with the new system!
It has taken a while to get used to the system and we're still working out the best way to run it. Currently, we turn a generator on at 8 am and run the power-hungry scuba compressors to fill the air bank for the day's diving. Excess power is channeled to the batteries which are low after powering the station the previous night. At about 10 am, the generator is turned off and the sun then provides enough to power the station during the day and to increase the charge in the batteries. We then leave the computer to control the system. It's set to start a generator when the battery charge falls to a particular level, and that generally happens at about 10 pm. The generator runs until the batteries are charged to about 90%, which takes four to six hours. The generator then switches off automatically in the early hours of the morning and we run on battery power until 8 am.
Energy audits conducted during the design phase for the system showed that our highest power draw occurs in the late afternoon and early evening - just as the sun is getting low. That is when people return from the field and are cooking dinner. Now that we have a feel for how the system works on "automatic", we will probably change the parameters to match that usage pattern. We hope that it will work to run a generator from about 4 pm. By 9 or 10 pm, there should be enough charge in the batteries to run the station throughout the night - and give us all a good night's sleep without the generator rattling away in the background.
The system comprises:
- 144 solar panels capable of producing 30kW of power
- 288kWh of sealed gel batteries
- 30 kW inverter
- existing diesel generators
The Sanyo solar panels used at LIRS are specifically designed to perform well in the high temperatures experienced in the tropics. They are mounted on a purpose-built structure that is 32 metres long. Underneath the structure are two rooms that house the batteries, the inverters and the equipment to control the operation of the solar power and the interface with the generators.
The generators now operate much more efficiently. Before, their output was governed by power draw and there had to be excess capacity to avoid blackouts. This meant that fuel usage was not optimal. Now, when the generators are on, they are always operating at high output. This uses fuel more efficiently and excess power is stored in batteries for later use.
The whole system cost $550,000, most of which was funded by money raised for the 30th Anniversary Development. Two special purpose grants from the Fred P. Archer Trust (managed by The Trust Company) and one from Abercrombie & Kent Philanthropy contributed to the cost of the solar panels. Completion of this system now has been made possible by deferring some other upgrade works, as the $200,000 Federal Government subsidy that was budgeted for the solar system was canceled at short notice by the Government in 2009.
Bob Lamb, long-time maintenance staff at Lizard Island, is to be congratulated for the planning and implementation of this system. The engineers who commissioned the control system complimented Bob by saying that it was the best organised system they had seen. Instead of the normal three-day period needed to commission a system of this size, they were able to complete the job in just one hour!
We thank the Lizard Island Reef Research Foundation and all donors to the 30th Anniversary Development Project for enabling this wonderful new facility.
Some text for this post was contributed by Charlie Shuetrim.