“The fascination of a growing science lies in the work of the pioneers at the very borderland of the unknown, but to reach this frontier one must pass over well traveled roads; of these one of the safest and surest is the broad highway of thermodynamics.”— Gilbert Lewis (1923)
With growing global concerns about reducing carbon emissions, the power industry has received its share of focus and it’s undertaken a number of approaches to address carbon, including raising plant efficiencies, switching to natural gas, and trying some different technologies. Fuel switching to gas is the primary strategy in the United States as gas is abundant and coal plants often don’t meet new environmental requirements without significant investments.
In Asia, where coal is both abundant and a staple, utilities are building ultrasupercritial plants that increase efficiencies by about ten percent while reducing carbon emissions. They refer to it as clean coal.
What about completely different approaches? Earlier this week, the New York Times published several pieces about clean coal, one of which involves gasifying coal to produce Substitute Natural Gas (SNG), which is then combusted in a combined cycle plant. This technology is attractive in that one can remove almost all of the carbon in the process, in the form of CO2, during gasification.
This CO2 can then be stored underground or used for enhanced oil recovery. Integrated Gasification Combined Cycle (IGCC) plants like these look like a good solution on paper, but since Kemper County and the recently completed Edwardsport facilities were essentially technology “firsts”, they cost a lot more than their original budgets.
I’m convinced that none of these plant types offers viable long-term solutions as their cost per MW of production are higher and they are not good at cycling load, something that is an operational must in today’s world of intermittent renewable power.
Enter another approach that is interesting, both from the thermodynamics and technology standpoint. NET Power is building a facility based on a new process, the Allam cycle, which will use natural gas as the feedstock and has zero emissions. It’s the first plant that I’ve seen without any kind of stack. One of the real differences in this process is that steam is not used, rather, supercritical CO2 is the motive force for the turbine.
The first demo plant is being built in Texas, and because it’s new, it’s likely to cost more than originally budgeted. However, this technology offers a unique approach, with a smaller footprint, that is being looked at by other utilities as a means to produce reliable power with no carbon output. Time will tell if the technology delivers on its promises and is scalable.
From Jim: You can connect and interact with other power generation and control experts in the Power group in the Emerson Exchange 365 community.
