The Geothermal Energy Association bills its annual expo that opens in Reno next weekend as the largest gathering of companies in the geothermal industry in the world.And it's the rest of the world that will be getting of much of the attention on the expo floor and the associated meetings of the Geothermal Resource Council as economics and politics take some of the steam out of the geothermal industry domestically.More than 2,000 people ranging from engineers to equipment manufacturers to utility finance experts are expected to spend time at the event, which runs from Sunday through Oct. 3 at the …