Mar 10 2008

Pumping Carbon Dioxide to Generate Power…and More Posted by Angela Baker in Untagged

A new study administered recently by Lawrence Berkeley Laboratory appears to show that by pumping carbon dioxide through hot rocks two different positive effects can be realized.  First, this method has the ability to generate power, which has obvious effects in regards to the currentthe current modes of producing power.  In addition to this advantageous result, by propelling the carbon dioxide through the hot rock, these dangerous greenhouse gases that are produced by fossil fuel power stations may be absorbed.

 

Karsten Pruess, the hydro-geologist at Lawrence Berkeley Laboratory who carried out this studied, claims that "carbon dioxide could theoretically boost the amount of energy produced by hydrothermal plants by 50% or more...." and that "the technique could be used to dispose of the carbon dioxide produced by conventional power plants, which contributes to global warming."

 

In order to take control of the geothermal power, heat must be extracted from below the surface of the Earth.  This new method being studied by Pruess can extract this heat more efficiently than the current method, which involves water being pumped through the hot rocks and subsequently being extracted again.

 

Pruess' hypothesis prior to utilizing the Soultz hydrothermal plant located in northwest France was that his method would be more resourceful than the plant's method of pumping water.  Though he was not completely confident in this hypothesis prior to commencing the study, he learned that it is beneficial to take risks and attempt new solutions.

 

On top of the fact that driving carbon dioxide through the hot rocks produces more energy by up to 50 percent, it also necessitates less energy to be used in undertaking the process.  This is due to the fact that the hot gas in the exit hole of the rocks is less impenetrable than the cooler gas at the entry, subsequently meaning reduced pumping would need to be done because of this density.  Overall, this novel idea appears to be a win-win situation regarding the proposal of a new form of renewable energy. 

 

Let us also look to the second aspect of absorbing the dangerous greenhouse gas that carbon dioxide is.  According to Pruess' study, it seems to be inevitable that some amount of the gas would seep into the rock, storing the carbon dioxide.  Although this seems like it would be an extreme positive, Robert Pine of the Camborne School of Mines in the United Kingdom thinks there could be some adverse affects from this. 

 

His take on it is this:  "While carbon dioxide is unlikely to escape from such traps, rock fractures, which are common in regions used for hydrothermal operations, could allow gas to leak out.  Using gas fields might be better, but because they aren't very hot you would have to go very deep to get to the heat."

 

So, although he still appears to, in general, advocate the idea that Pruess has proprosed, in his opinion there are precautions that should be taken to ensure the most advantageous results from the new method.