Make no mistake here; SRI International has the brainpower and skill set to come up with workable and commercial ideas that have scale in mind from the start.  Robert Wilson, Ph.D., director, Chemical Science and Technology Laboratory, SRI International said in the press release, “The implications of this research are expansive, including enhancing US energy security through the use of domestic carbon sources. The process can also dramatically reduce the environmental footprint associated with alternative transportation fuels.”

Simply put, SRI has a method to make use of the dense proportion of carbon in coal and reform it with high content of hydrogen in natural gas to make liquid hydrocarbon products. For the U.S. that has major energy security implications.

SRI’s promising new way to produce liquid transportation fuels from coal does not consume water or generating carbon dioxide.  The hydrogen that water provides in other processes is substituted by the natural gas.  With the energy requirement for hydrogen splitting from the water absent and the combustion of the coal the process reduces the CO2 produced.

The natural gas for water substitution also reduces the need to add energy to drive the gasification reaction, and results in the use of a smaller gasifier. In conventional coal to liquids approaches, energy is supplied by burning a portion of the coal feed, which then produces carbon dioxide. SRI’s approach makes it economical to use carbon neutral electricity, such as nuclear, hydro, or solar as a source of additional energy.

The new SRI process uses the hydrogen in the natural gas to convert coal making an uprated hydrogen rich syngas (a mixture of carbon monoxide and hydrogen). The coal first decomposes into volatiles and char while CH4 is converted into CO/H2 mixtures; the char is converted into CO/H2 mixtures via steam gasification on longer time scales.  The syngas is first converted into methanol that can then be efficiently processed to make the desired transportation fuels.

Based on data from their bench-scale tests, SRI engineers estimate that the capital cost for a full-scale plant using the new process would be less than half that of a conventional coal-to-liquids (CTL) plant that uses the familiar and common process called Fischer-Tropsch Synthesis (FTS). FTS produces only a small fraction of the hydrocarbons needed for fuel and requires extensive recycling.

SRI has performed a series of analyses to examine the environmental impact of the technology under several scenarios. Conventional diesel comes in at 389 gCO2/mile, conventional FTS coal-to-liquids diesel at 830 gCO2/mile; and the SRI synthetic fuel at 326 gCO2/mile when using carbon-neutral electricity power. Based on their analyses, if diesel were produced using biogas as the natural gas source for the methane, the resulting emissions would be 190 gCO2/mile and the product would qualify as an alternative fuel under the revised Renewable Fuels Standard of the Energy Independence and Security Act of 2007. The Act requires alternative fuels to meet a standard of 50-percent reduction of greenhouse gas emissions compared to other fuels.  That will get the attention of the coal folks.

Ripudaman Malhotra, associate director of SRI’s Chemical Science and Technology Laboratory presented the process at the 28th Annual International Pittsburgh Coal Conference pointing out the SRI process converts all the carbon to product, reduces capital cost, has adjustable syngas ratios to produce CO + 2H2, ideal for methanol; and uses efficient COTS (commercial off-the-shelf) technology for the methanol to JP-8 conversion.

SRI estimates the efficiency of its CTL plant at 67% – significantly higher than traditional CTL plants, mostly because it is converting 100% of the carbon feed into product and it utilizes electricity generated off-site. Accounting for the heat rate of generating that electricity from a traditional coal plant would still result in a plant efficiency of 47%.

But those efficiencies are a bit misleading – The cost per gallon for the SRI diesel fuel product is calculated at $2.81.  That’s still higher than FTS at $2.14, where virtually all the energy comes from raw coal and a great share of the carbon is lost to CO2 in making the fuel and lots of energy goes to getting the hydrogen from water.

If the goal is low investment, downsized installations with low emissions and full use of the raw materials the SRI process is quite attractive.  That plus the process itself offers more than the middle distillates of diesel and jet fuel.  There’s crude methanol, gasoline, propylene, and propane as well – plus some mineral ash.

The SRI process likely has commercial legs.  Whether or not a facility is built will consider the raw materials cost along with the investment.  Another question comes to mind when looking over the process flow diagram.  Would any of the concepts here transition to the oil shale deposits of the western U.S.?

See article here.