CO2-EOR and Carbon Geological Sequestration

The climate bill passed by Congress on June 26, 2009, the American Clean Energy and Security Act (H.R. 2454), has a lot of curious and wishful provisions but none can match the requirement that U.S. reduces its carbon emissions in 2020 by 17% below 2005 levels and by 2050 by 83%.  Let’s ignore the rather remote 2050 and look at the situation in the more foreseeable 2020.

The bill does not really say how these reductions are to be accomplished. One is the cap and trade, which in spite of its benign title is not really intended to reduce CO2. People and companies can continue business as usual as long as they pay some others who do not emit. Think of this as some sort of indulgence papers, the medieval way of gaining heaven by simply paying and allowed to be a sinner.

This will do nothing to remedy global warming. Because the likelihood of moving away from fossil fuels towards others that do not emit CO2 in such short period of time is negligible, the only way that the mandated CO2 reductions can be accomplished is through sequestration (storage.) The solution, proposed by many, is geological sequestration.

One suggestion is to use CO2 for enhanced oil recovery (EOR). It is important to put this idea in perspective in view of the recent legislation but also because of claims and efforts by certain universities and national laboratories to present the obviously overwhelming economic and industrial burden as an opportunity.

As of June 2009, the U.S. use of CO2 for enhanced oil recovery (EOR) was 3 billion standard cubic feet per day, equivalent to 63.5 million tons per year, of which 83% is from natural underground CO2 reservoirs.  Only about 10.8 million tons come from industrial (anthropogenic) processes.

According to the Energy Information Administration (EIA), the U.S. emitted 6.55 billion tons of CO2 by fossil energy utilization in 2005 (the world figure was 30.53 billion tons in 2005).  EIA also projected that the U.S. CO2 emission from fossil energy will be 7.65 billion tons in 2020.  If Bill H.R. 2454 is to be complied we have calculated that a total of 13.353 billion tons of CO2 from 2010 to 2020 must be stored, assuming that CO2 will be stored starting from 2010, as shown in the following table.

Take any arbitrary year, e.g. 2015 and therefore 1.222 billion tons must be stored somehow. The current EOR use of 63.5 million tons is about 5 percent of the 2015 mandated amount and most likely it will become smaller. By 2020, unless CO2 EOR projects pick up at an unprecedented pace, they will amount to less than 3 percent of the EOR to be stored.

In fact, with total (not annual) US oil reserves currently estimated by EIA at 21.5 billion barrels, if a huge part of 10% of this could be enhanced via carbon dioxide injection, the amount would represent on the order of 2 billion barrels, or about 250 million tons of CO2, about 20% of the mandated target for annual 2015 (not total) CO2 reduction.

This is the best possible scenario of CO2 use that would fit both the mandated sequestration and application as an opportunity for EOR. For true sequestration, injecting into a closed system, the problem is orders of magnitude more cumbersome. Our calculations suggest that sequestering the CO2 emitted from just one 500 MW coal power plant for a 30 year period would require a reservoir whose pore volume is larger than Alaska’s Prudhoe Bay field, the US largest. This will be a subject of future publications.

The irony is that much of the national debate and even discussions among some technical professionals have centered around the logistics and costs of capture, transmission and injection, ignoring the obvious: the physical impossibility to store the volumes of the mandated CO2 reduction. EOR applications cannot be the solution for any significant part of the total volume of CO2 that needs to be managed. More than 95% of the mandated volume to be sequestered simply cannot be done.  So, the only way this bill can have any effect is by the witchcraft, feel-good of cap and trade.

The question is why Congress would enact legislation whose presumed provisions of reducing emissions that ostensibly cause global warming simply cannot be physically met at any cost. Studies such as the ones described here are elementary and can be done by young undergraduate engineering students.