Introduction

Since the dawn of the Industrial Age, mankind has created an evolutionary web of increasingly efficient machines. It's because of our desire for efficiency, that today we have cars that can drive for hundreds of miles without refueling, water treatment facilities that filter particulates at the microscopic level, and supercomputers that control the device in your pocket from a server farm in Southern California. The world is changing with recognition to our technological advancements and we require new methods to increase power efficiency if we hope to sustain a prospering ecosystem into the future. In this assignment, I evaluated the costs and benefits of adopting a new technology known as Carbon Capture and Storage (CCS).

Whenever a fuel source is burned (usually in an attempt to generate electricity or light) greenhouse gasses are emitted into the atmosphere. Of these gasses, carbon dioxide (CO2) is the most prolific. In 2008, the Carbon Dioxide Information Analysis Center reported CO2 emissions to be over 32 billion tons worldwide. To put this into perspective, the estimated CO2 concentration worldwide was 280ppm in the age prior to the Industrial Revolution. The year is now 2012 and the average CO2 concentration on any given day is roughly 390ppm (Δ110ppm). At our current rate of pollution, the concentration of CO2 in the atmosphere rises by about 2ppm each year. Biological experts agree that the most CO2 content humans can intake while maintaining a healthy immune system is 500(±50) ppm. The rate of emissions in the United States has slowly decreased since 2008, thanks in part to new sustainable technologies like wind and solar power, but China has quickly advanced from a developing industrial nation to the single heaviest polluter on the planet. If all of this sounds ominous, it's because it is.

To offset the overall impact of CO2 emissions in the atmosphere, researchers around the world have begun to venture into the idea of capturing the greenhouse gas before it has a chance to escape from its emission source. There are a number of ways to extract CO2 from ventilated air. Engineers may use pre-combustion, post-combustion, or oxyfuel capture to separate the gas from its initial fuel source. When pre-combustion is used, the fuel source is gasified using O2 and steam to produce CO2 and H2. The hydrogen produced can be used as a direct fuel source while the carbon dioxide is captured separately. In post-combustion, CO2 is simply captured after the fuel has been used for power/heat generation in a unit that can be attached to the smokestack of the facility. Very little effort goes into modification of the existing design and this method generally provides higher efficiency rates than pre-combustion methods. The oxyfuel capture method is more expensive than the other two options, but produces the highest thermal efficiency. The captured CO2 is then pumped into a storage tank under high pressure to utilize space the most efficiently. Heavy transport trucks then move the canisters of compressed gas to a location off-site for storage.

The sequestered CO2 is now ready to be put to use. Companies that drill underground wells to harvest oil and other liquid fuels will be quick to purchase this stored CO2 as it provides a pressurized assist when extracting oil from “depleted” mines. These underground caverns, that were once thought to be used to their full extent, are now available to recover oil from again thanks to the aid of compressed CO2. Engineers in the field estimate that as much as 40% of the total oil accumulated in the wells could be extracted with the aid of compressed CO2 in a process called enhanced oil recovery. The low-pressurized hole where the oil was residing is now filled with compressed CO2 to compensate for the change in pressure. Another similar use for the captured CO2 is to store the gas in underground fault lines where the pressure would add stability to the surrounding geometry. These underground pockets are often filled with highly saturated brine. It is crucial that the CO2 is stored below 1km from ground level to minimize the risk of gas migration. A sudden release of compressed CO2 could be fatal. Monitoring stations may be necessary to detect whether the gas is maintaining pressure deep within the Earth’s crust.

CCS Diagram

Carbon Capture and Storage (© 2012 “Innovation Group – CNS UCSB”)

As CCS technology matures and becomes increasingly more effective in large power plant systems, the amount of CO2 that can be sequestered will increase over time. With the combination of newly developed power plants utilizing this technology, along with the maturation of the carbon capture process, CCS is likely to completely eliminate CO2 emissions at the largest energy plants in the world’s most developed countries. The potential emission reductions could extend well into the thousands of million metric tons of CO2 annually in just the US alone. Because the technology is still relatively new and requires years of research to advance towards different uses, we likely won’t see CCS implemented into mobile CO2 emission sources like vehicles and aircraft for at least another 50 years, if ever.

It is important to implement CCS technology as soon as possible if we are to reduce our effect of harmful CO2 emissions into the atmosphere. Even if we installed CCS modules on all of the largest power generators all over the world today, CO2 emissions would remain at their current level for almost a century before average atmospheric CO2 decreases to a level below 350ppm. In short, it’s going to take some time to recover from the damage we’re currently inflicting on the planet. It’s also important to note that CCS is not the end-all solution that will solve the issue of our global carbon footprint. Other factors such as efficient electrical/lighting systems need to become increasingly popular in both residential and commercial buildings, and alternative combustible fuels need to be considered for use in gasoline engines to combat the influence of CO2 that the millions of active cars and trucks impose on a daily basis. As these different technologies become supportive of one another, our global carbon footprint will become increasingly manageable.

Power plants in the United States account for 97% of CO2 emissions in the country. If the government dedicated funding to post-combustion CCS methods on every large-scale power plant in the country, we could see global carbon concentrations begin to level out in the near future. A considerable goal would be to implement carbon capture methods on roughly 2% of point-source power generation plants in the US every year. With this adoption rate of CCS technology, nearly every large power-generating facility in the US would sequester their CO2 in 50 years from now. The potential reduction in greenhouse gas emissions is significant. In 2010, the US emitted 5,610.11 teragrams (or million metric tons) of CO2 through the use of energy production plants.

Calculations

(5,610.11 Tg CO2) ∙ (50 years) = 280,505.5 Tg Emitted CO2              NULL

(5,610.11 Tg CO2/year) ∙ (0.02) = 112.2022 Tg CO2/year                   2% GOAL

(112.2022 Tg CO2/year) ∙ (50 years) = 5610.11 Tg Captured CO2      POTENTIAL

(280,505.5 Tg CO2) – (5,610.11 Tg CO2) = 274,895.39 Tg CO2          OVERALL

*Assumes that no power generation plants are added to the system over the next 50 years.

Conclusion

From the calculations above, we can see just how massive the energy-production emissions in the US really are. The amount of carbon that is emitted annually is a number easy for most of us to quantify. However, when the scale is increased to a number of decades, the amount of CO2 emitted into the atmosphere is nothing short of astonishing. With the suggested acceptance rate of CCS technology at 2% per year, it would take 50 years to implement carbon capture at 100% of the power-generating facilities in the US. Yet even after CCS is fully adopted, we will have produced 50 years’ worth of CO2 in the time it took to install the carbon sequestration units. This also assumes that no power-generating facilities are created in the near future to support a growing demand for electricity. Cities are growing and human population rates are increasing exponentially. Nevertheless, it is essential that we take action now to prevent further CO2 emissions from shaping the environment we strive so hard to control. Carbon Capture can help us achieve it.

 

Works Cited