Either no emissions or just steam are visible. These qualities reduce the overall visual impact of power plants in scenic regions. The long-term sustainability of geothermal energy production has been demonstrated at the Larderello field in Italy since 1913, at the Wairakei field in New Zealand since 1958, and at The Geysers field in California since 1960. Pressure and production declines have been experienced at some plants, and operators have begun reinjecting water to maintain reservoir pressure. The City of Santa Rosa, California, pipes its wastewater up to The Geysers to be used as reinjection fluid, thereby prolonging the life of the reservoir while reusing wastewater.
Some plants can charge more during peak demand periods.
Costs of a geothermal plant are heavily weighted toward early expenses, rather than fuel to keep them running . Well drilling and pipeline construction occur first, followed by resource analysis of the drilling information. Next is design of the actual plant. Power plant construction is usually completed concurrent with final field development. Hot geothermal fluid with low mineral and gas content, shallow aquifers for producing and reinjecting the fluid, location on private land to simplify permitting, proximity to existing transmission lines or load, and availability of make-up water for evaporative cooling.