Energy policy — geothermal: Governor’s Energy Office San Luis Valley geothermal workshop recap
February 28, 2010
From The Pueblo Chieftain (Matt Hildner):
…a group of state officials, business owners and the just plain curious sat down Saturday to talk about a resource beneath their feet at a geothermal workshop hosted by the Governor’s Energy Office…
Nearly 150 million acre-feet of water, much of it hot, sits beneath the valley in the confined aquifer, the deeper of the valley’s two major groundwater formations. Paul Morgan, senior geothermal geologist with the Colorado Geological Survey, said the state was gifted with a high heat flow. That characterization included the Rio Grande Rift, the geological formation that runs beneath much of its namesake river, but Morgan said there is not a lot of specific data about the resource in the area. “We don’t know a lot about most of the San Luis Basin,” he said.
What is known suggests that hot water at a temperature of 200 degrees Fahrenheit can be found in most parts of the valley at about 5,000 feet below the surface. The depth and temperature qualify it as a low grade and likely not of the quality that would be needed to produce electricity. Morgan suggested that the depth to the resource could be as shallow as 2,000 feet in areas where the aquifer had up-flow zones. But he added that the valley’s resource would be suitable for ground-source heat pumps. “They’re very good at heating, but they can’t compete with swamp coolers in terms of the economics of cooling,” Morgan said…
The water use that comes with geothermal development would be regulated by the Colorado Department of Natural Resources. Users who don’t reinject the water they’ve used to harvest the heat will face a requirement to replace or augment their depletions, said Pat McDermott, staff engineer for the department in the valley. And eventually, should enough users tap the resource, McDermott said his office would have to ensure that new users don’t impact the temperatures of existing wells. “As it gets more and more evolved over time, well-to-well impact on temperature is going to become a big deal,” he said.
