Editor,

Great to see the active interest in energy options for Tonga.

With regards to coconuts, it would be terrific if we could find a use for them other than falling on windshields. Unfortunately my analysis shows based on 100 coconuts/tree/year and 100 trees per hectare that it would take 14,000 hectares (70% of Tongatapu) of coconut trees to provide the energy equivalent of 700 hectares of Saafa or Siale Mohe Mohe. Not to mention the difficulty of collecting the coconuts versus mechanized mowing of flat straw/bush pastures.

I have no issues with using solar power on Tonga's small islands but at the end of the day what will make or break Tonga's economy is the cost of electricity on Tongatapu and Vava'u and the high capital cost of solar excludes it as a source of cheap electricity for the population centers. Unfortunately the interest and amortization costs per kWh of a solar plant are much higher than the estimated TOP 0.09/kWh cost of Saafa or Siale mohe mohe.

However if someone has an economic analysis that shows either of these options to make sense then I may have to eat a second hat when this evidence is presented to the consultants soon to prepare yet another study of energy options for Tonga.

Peter Goldstern

goldsternp [at] alum [dot] mit [dot] edu