The newest issue of the Electric Power Research Institute Journal is just out and focuses on carbon capture. The most informative article is The Challenge of Carbon Capture which reviews the current state of R&D activities for CO2 capture of coal fired electric plants. The article cites estimates of 10%-25% increased cost of electricity for plants with 90% carbon capture. Everything is in the experimental stage and no one is really sure how feasible underground storage can be on a large scale and over the long term.

Given the vast scope of the coal industry, progress on this front seems half-hearted and very slow. The industry is based on digging up stuff, shipping it to a furnace, and burning it. To date, environmental controls consist of bolting a filter onto the smokestack (a simplification, but correct from the plant manager's point of view).

Unfortunately, carbon capture is probably beyond the institutional capacity of the coal industry. Assuming there is any progress, it will be a constant battle and with constant pressure -- political, financial, administrative -- to cheat and backslide. The folks who are truly interested in clean energy are not, by and large, devoting their efforts to coal.

Even with 90% carbon capture, coal plants will emit more than renewable sources. (Renewables have emissions during the fabrication and construction phases.) Let's see some real analysis by engineers and economists. Right now, the national debate is hugely biased. As Kelpie Wilson points out,

"While the EPRI study [favoring nuclear and coal] was covered in the New York Times and elsewhere, the ASES study [favoring renewables] was covered by only two news organizations, The Daily Camera out of Boulder, Colorado, and Truthout."

and capturing it at the same factory that makes it is not necessarily the best approach. Yes, it's concentrated in the chimney and gets dilute if let blow 10,000 km downwind, but the thermodynamic penalty of undoing that dilution turns out to be not all that burdensome.

The CO2 affinity of the mineral serpentinite turns out to be enough to do this concentration. It might be dug up and pulverized on a 100-GW scale and thrown onto the wind. Long plumes of suspended dust turning from MgSiO3 into MgCO3 and SiO2 seem like something that the Earth might have places for where they would be fairly harmless; or otherwise said, if those plumes, judiciously sited, would be worse than AGW, then AGW must not be very bad.

The economy-of-scale advantages of centralized capture on a much larger scale than one coal-burner would be able to do with its own flue gas may more than compensate. Also, the rich countries can do in a spirit of making sure their end of the lifeboat doesn't sink, even if it means the poor countries at the other end of the boat get a free ride.

Anything cheaper and easier than dirty coal will have a rough ride from the fossil fuel interests, especially the fossil fuel tax interests; that is one sign that nuclear is the real deal, and is opposed only by fossil fuel interests.

--- G. R. L. Cowan, former hydrogen-energy fan
Oxygen expands around boron fire, car goes

Sunflower wrote: Triple solar deployment to equal coal's capacity factor and the numbers become $0.45/W(t) solar collector v. $0.58/W(t) coal boiler.
[...]
Bottom line is that high quality solar energy is cheaper than coal in the US, China, India,....

world-nuclear.org/info/inf10.html

A solar thermal power plant has a system of mirrors to concentrate the sunlight on to an absorber, the energy then being used to drive turbines. The concentrator is usually a parabolic mirror trough oriented north-south, which tracks the sun's path through the day. The absorber is located at the focal point and converts the solar radiation to heat (about 400oC) which is transferred into a fluid such as synthetic oil. The fluid drives a conventional turbine and generator. Several such installations in modules of 80 MW are now operating. Each module requires about 50 hectares of land and needs very precise engineering and control. These plants are supplemented by a gas-fired boiler which generates about a quarter of the overall power output and keeps them warm overnight. Over 350 MWe capacity worldwide has supplied about 80% of the total solar electricity so far. Power costs are two to three times that of conventional sources..

Sunflower wrote: A typical US modern coal power plant [...] One-third of the heat is converted to power.

...Or half the heat is converted to power, depending upon how hot the coolant water is.

worldcoal.org/pages/content/index.asp?PageID=421

Supercritical (SC) and ultra-supercritical (USC) power plants operate at temperatures and pressures above the critical point*. This results in higher efficiencies - up to 46% for supercritical and 50% for ultra-supercritical.

The National Renewable Energy Laboratory publication Assessment of Parabolic Trough and Power Tower Solar Technology Cost and Performance Forecasts found the cost of solar thermal could drop over the next few decades to well within the range of coal or nuclear.

The figure and table below highlight these results, with initial electricity costs in the range of 10 to 12.6 ¢/kWh and eventually achieving costs in the range of 3.5 to 6.2 ¢/kWh.

The cost reductions will come from volume production, plant scale-up, and technology advances (such as the Schott receiver, which is already in mass production).

Natural gas assist may or may not be employed with solar thermal. It is not required and solar thermal plants can function well with 100% solar input.