Carbon Capture and Storage Cost Comparison

So I was doing some digging and found some old notes I had made while reading about Carbon Capture and Storage (CCS) techniques. These are schemes that seek to trap Carbon Dioxide (CO2) and store it somewhere, usually underground, rather than emit it to the atmosphere. CCS is largely sold as a solution to reduce climate change, but it can also provide a source of CO2 for end users like oil fields using enhanced oil recovery.

There are literally dozens of different schemes out there, and I wanted to compare the cost of each when it came to reducing carbon dioxide emissions. Trying to do an apples-to-apples comparison of is extremely difficult, but what I did was go through three sources:

  •  IPCC, 2006. “Intergovernmental Panel on Climate Change (IPCC) Special Report on Carbon dioxide Capture and Storage Chapter 3: Capture of CO2” Cambridge University Press, Cambridge, England.
  •  EcoBusinessLinks, Feb. 14 2010. “Carbon Emissions Offset Directory - Price study of offsetting emissions of carbon.” http://www.ecobusinesslinks.com/carbon_offset_wind_credits_carbon_reduction.htm
  •  MacKay, David. 2009. “Sustainable Energy – without the hot air.” UIT Cambridge Ltd., Cambridge, England. http://www.withouthotair.com/ (Relevant old post here)

…and then I tried to put everything in the form of $US per metric ton of CO2 release avoided. All prices are from 2000-2010, for the U.S. lower 48, and I did not make any adjustments for inflation or location. Prices are averaged over the lifetime of the plant or service, so something with high upfront costs but a long lifetime can have a lower cost than a cheap but short-lived solution. None of the prices include compression and storage, because that price varies very heavily based on how close the storage location is.

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Convert Units Easily with Factor-Label Unit Conversion

Converting units is a very common work task, and trying not to get tripped up by it is a real pain at times. I'm sure you've already read the Mars Rover and other trite examples, so what can we do?

We have already discussed some methods to help convert units (like the Google Search Tricks and unit conversion program articles), but today we go beyond programs into what you might call a technique, or a frame of reference. It's a way to think through and record your unit conversions that I find clear remarkably and error-resistant, whether you are working by hand, by computer, or both: the factor-label method.

The factor-label method begins by observing that anything multiplied by itself is one. For example, consider arbitrary variable “x.” We know that x * 1 = x, therefore x * 2/2 = x, x * 325235/325235 = x, etc. So mathematically, we can multiply any value by "one" without changing it. Next, we realize that equivalent amounts of a unit are equal, so they can be considered “one.” For example, 100 cm = 1 m, therefore 100 cm / 1 m = 1, in a sense. 16 ounces / 1 pound = 1, etc. Continue reading

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Sorry for the service hiccup, we are back.

I may have some posts about project economics and Net Present Value, materials handling, pressure/vent calculations, or other items in the future.

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Fouling Factors for Heat Exchanger Design

In this post I’ll list a few resources to find fouling factors for your heat exchanger designs. But first, let’s take a step back and review the definition and purpose of fouling factors in heat exchanger design.

And I thought they smelled bad...on the outside!

And I thought they smelled bad...on the outside!

Recall that in the heat exchanger sizing equation Q = U * A * LTMD, the “U” factor was a representation of all the resistances of heat exchange between the two sides. “U” was influenced by the types of fluids in the exchanger and also to a lesser degree by the material of construction of the heat exchanger. The fouling factor helps us add some additional detail, by representing the extra resistances that appear on the inside and outside of tubes after an exchanger has been operating awhile: the caked on products of fouling. There are different types of fouling, from crystalline scale to literal pieces of gunk. Fouling introduces a wrinkle into our simple equation, because now the resistance to heat exchange varies over time. But we still have to pick one exchanger design and one “A” value for the entire cycle of operation.

A properly chosen fouling factor will inform the detailed design of heat exchangers by vendors and/or software. As always, the best values to use are real-world values based on experience or tests in your own plant. Nevertheless, it’s helpful to have literature values for a starting point.

Some Literature Sources for Fouling Factors

Note that some of these links are PDF files: Continue reading

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