DCFC: An Ecologically Friendly Technology

Direct Carbon Fuel Cells are based on coal gasification technology. This technology has already been around for about a century and may yet prove to be a 21st century base-load energy source, and help free our grids from the emissions of traditional coal and natural gas.

Basically, after a high temperature conversion process gasified coal can be consumed by an electrical power station and generate nearly twice the energy of coal while halving the GHG waste! For those concerned with emissions or climate change, this means that modified coal could emit about 250 grams of CO² per KW/hr or 550 pounds of CO² per MW/hr – however you’d prefer to measure emissions. This is about the levels originally outlined in the EPA’s Clean Power Plan, but much closer to needed reductions. Also, gasifying the coal will eliminate solid fly ash and allow extraction of other impurities.

DCFC's will have a capacity factor of 65 percent - with ultra low emissions.

DCFC’s will have a capacity factor of 65 percent – with ultra low emissions. Graph based on NEI data.

 

The Energy Reality Project would like to re-post two pieces on this subject.
One from (Th)e Kral Spaces, a blog generally concerned with the nuclear biosphere. The other is a guest post by Robert Steinhaus at the Molten Salt Science International’s beta site.
Please, feel free to leave any constructive comments or questions below.

 

Coal energy cheaper than coal energy”
as originally posted at https://kralspaces.wordpress.com/

The only reason China is investing in everything possible for their energy mix is because they need more energy then they can generate. Once their energy catches up to their demand they will be able to take a serious look at what energy sources are the most efficient and narrow their scope to what can be considered clean energy. Once their focus on quantity is turned to quality, hopefully they will still include fossil fuels. Really?

There is a needed mix for energy and it includes fossil from my perspective. I struggle to understand why the Obama Administration wants to throw coal under the bus. If we change the way we look at coal, it too can be a cleaner energy source. If we convert coal to electricity via electrochemical oxidation without burning it, we can generate twice the electricity with half the coal and manage the waste without a variety of toxins ever getting release into the atmosphere. We have managed nuclear waste for 60 years so we already know how to do it safely.

The concept is called Direct Carbon Fuel Cells (DCFC) and Lawrence Livermore National Labs (LLNL) has demonstrated this technology as far back as 2005. Why no one is interested in this solution stuns me just like the Molten Salt Reactor (MSR) oversight for clean safe nuclear energy did fifty years ago. Natural gas and oil can also be used as a source for this DCFC process and the best part is that it already comes with an existing commercial electrical power generation infrastructure.

I’ve written a short paragraph about DCFC in a previous column but I strongly believe the Unites States Coal Industry needs to take a serious look at this potential technology. There are several reasons why I take this position and the first and most obvious is that the Coal Industry is on the chopping block with the latest EPA regulations. The new regulations have to do with clean air and water from the coal burning process to generate electricity. The EPA itself admits that the plan’s usefulness against the threat of climate change will be so small that it will be impossible to measure. If you eliminate the ‘burning of coal’, you eliminate the need for new regulations and many of the older regulations as well.

Coal is the cheapest source we have to generate electricity today. The fact that there is already a well established infrastructure for mining coal, it only makes business sense to leverage that infrastructure and only change that process which needs to be changed – the burn. At a fraction of the cost to build an equivalent nuclear power plant or renewable wind and solar farm, a new DCFC Converter can be built right next to the existing coal furnaces and the output fed directly into the electrical grid without having to go through a secondary steam turbine process. Wow! That would lower the cost of processing tremendously and make electricity generation from coal cheaper than coal. There is a little sarcasm in that last sentence because coal is the cost baseline for all other energy sources.

There is a book I read recently titled “The Moral Case for Fossil Fuels” and it addresses the abundance of what fossil fuel has contributed to our extraordinary life style. Even as an advocate of nuclear energy, I just don’t understand the reasoning behind those you want to shut down coal production when clean coal can be achieved if we wanted to commit the effort to it.

DCFC Ref. Link: http://www.pennenergy.com/articles/pennenergy/2015/02/direct-carbon-fuel-cells-an-ultra-low-emission-technology-for-power-generation.html


DCFCs can give twice the efficiency of a coal plant for about half the price
as originally posted at http://mssci.com/

Robert Steinhaus contributed this about Direct Carbon Fuel Cells that can run on coal granules.

Molten Carbonate salt Direct Carbon Fuel Cells do not use a turbine-generator to convert heat to electricity. Each DCFC collects electrical charge internally on graphite electrodes inside the cell so a DCFC directly converts the chemical energy in coal into DC electricity. DCFC cells operate at high temperatures comparable to Molten Salt Nuclear Reactors (about 750 degrees C) and high temperature steels have to be used to make the fuel cells.

It is a feat to make a high temperature coal fired plant operate at more than 44% thermodynamic efficiency. DCFCs convert the chemical energy in coal to electricity at a repeatedly demonstrated efficiency of 80%. There is not Brayton turbine-generator on the planet that can approach the efficiency of DCFCs, and DCFCs do their job much more inexpensively than Brayton or Rankin turbines, have fewer moving parts, and require less maintenance.

Some downsides of DCFCs –
DCFCs have to operate at elevated temperatures between 700 – 750 degrees. To initially start a DCFC you have to heat the cell from an external source, although once started, internal exothermic heat of reaction will keep a cell at temperature.

DCFCs tend to be physically large cells for the power you can instantaneously draw from them (lower power density by weight). A DCFC might typically be 4X the volume of a natural gas or hydrogen PEM fuel cell which supplies the same amount of electrical power.

Since turbine generators are about half or more of the cost of most thermal fossil plants like coal fired power plants – not requiring a precision high temperature turbine-generator saves about half of the cost of a traditional coal power plant and make DCFCs very very high efficiency (80%) and very cheap (about half the cost of the nearest coal fired power plant competitor).

Small several hundred watt practical DCFC cells have been built at LLNL National Lab and operated for several months demonstrating 80% conversion efficiency. Commercial DCFC cells would be much larger and perhaps produce 10s of Megawatts of power each. Such large cells would turn high chemically energy dense coal into electricity directly without burning the coal. How often you have to replenish the DCFC cell would depend on how much power you draw out of the cell. You would get twice as much electricity from a given amount of coal using the fuel cell as you would get from burning the same amount of coal in a coal fired power plant.

The vast majority of the volume and weight of coal that you load into a DCFC fuel cell disappears into clear, colorless, and odorless CO2 gas that goes up a vent to the atmosphere or can be can be used in an industrial process or sequestered underground (no smoke, particulates, radiation, or other pollution into the environment to foul the local air quality). There is a ash or char produced by the cell which is around 5% by weight of the coal loaded into the DCFC. This ash/char has to be periodically removed from the fuel cell and disposed (when processed and the molten salts recycled – the char makes decent soil amendment for agricultural soils)

Answers to Frequently Asked Questions about Direct Carbon Conversion” by John Cooper
https://e-reports-ext.llnl.gov/pdf/317376.pdf

Editors Note: Here are some additional web-sites to learn about DCFC and the coal gasification process.  Start with an animation profiling the full process- https://vimeo.com/93110188

Atlanta based Southern Company is an energy provider with a DCFC program-
www.southerncompany.com/what-doing/energy-innovation/smart-energy/smart-power/kemper.cshtml
www.elp.com/articles/2014/04/southern-co-to-study-coal-power-with-chinese-state-firm.html

A more technical look at DCFCs, which will likely have capacity factors of 65%.
www.materialsviews.com/direct-carbon-fuel-cells-ultra-low-emission-technology-power-generation/

China has a strong program for alternate uses of coal as well-
http://instituteforenergyresearch.org/analysis/china-build-50-coal-gasification-facilities/
http://english.sxicc.cas.cn/st/rdds/200906/t20090601_19682.html

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