Progress may be slower than originally expected, but the Obama administration has continued to push for carbon capture and sequestration, a technology that removes carbon dioxide -- a greenhouse gas -- during the process of energy generation and stores the gas it underground so it doesn't go into the atmosphere and contribute to global warming.

During the 2008 presidential campaign, Obama said he would "enter into public private partnerships to develop five 'first-of-a-kind' commercial scale coal-fired plants with clean carbon capture and sequestration technology."

As we noted in our previous update, several proposed projects that received federal dollars during Obama's tenure were subsequently scrapped. Despite that, experts say that two projects are nearing the operational stage, two more are approaching the construction stage, and others are in earlier stages of development. Here's a rundown:

• Illinois Industrial Carbon Capture and Storage project, Decatur, Ill. Run by agricultural giant Archer Daniels Midland, the Illinois project received $141 million in stimulus funding and $66.5 million in private sector investments, according to the Energy Department. Once fully operational in the late summer of 2013, the project is designed to store up to 1 million tons of carbon dioxide created in ethanol production annually at depths of 7,000 feet.

• Kemper Integrated Gasification Combined Cycle, Kemper Co., Miss. Run by the MIssissippi Power Co., the Kemper facility aims to capture at least 65 percent of the carbon dioxide it produces as it turns lignite, a locally abundant form of coal, into a gas. The company claims that construction is 70 percent complete, though an outside analysis suggests it's more like 40 percent complete.

• Texas Clean Energy Project, Odessa, Texas. This Summit Power coal gasification project -- costing $2.5 billion, including $450 million in federal money -- intends to capture 90 percent of the carbon dioxide it produces. This carbon dioxide -- an estimated 2.5 million tons per year -- is to be sold for use in "enhanced oil recovery," a technique which uses the carbon dioxide to aid in the extraction of oil. The injected carbon dioxide either remains under ground, or if it returns to the surface with the produced oil, it is re-captured, re-compressed, and re-injected, resulting ultimately in permanent geological sequestration.

• Hydrogen Energy California Project, Bakersfield, Calif. Jointly run by several companies including BP and GE Energy, the project would convert 90 percent of the carbon dioxide produced in the making of hydrogen fuel and use it for enhanced oil recovery in an Occidental oil field five miles from the capture site. It is currently in the permitting stage.

• FutureGen 2.0, Meredosia, Ill. This $1.65 billion project has been reconfigured from a prior version that was cancelled due to escalating costs and other challenges. The current project would retrofit a coal plant so it sequesters 1.3 million tons of carbon dioxide per year in a saline aquifer. According to news reports, the project is several months behind schedule, which had been to begin design and engineering in 2012 and construction in 2013. The target date for electricity production and carbon storage is 2017.

At least three other projects are in less-advanced stages -- one in Indiana; another in Point Comfort, Texas; and one near Houston.

It's worth noting that -- in addition to questions about cost-effectiveness and technological suitability -- there is a split within the environmental community about whether carbon capture and sequestration should be pursued. Some groups see it as an important tool for fighting global warming, while others are skeptical of the technology or perceive it as too risky or having too many downsides for residents living near proposed plants.

Overall, the Obama administration has spent millions of dollars to help advance several commercial-scale power plants that are designed to use carbon capture and sequestration. There is a long way to go before this is a fully mature technology, but despite some significant bumps on the road, the administration has largely advanced its vision. We rate it a Promise Kept.