Liquid Fuels

Liquid Fuels and Hydrogen

All economic liquid fuels are hydrocarbons - molecules composed of carbon atoms and hydrogen atoms. The key to green liquid fuels is an economical, green source of hydrogen, a green source of carbon, and a source of energy to put them together in the right form.  Hydrogen is also the key to any other benefits of a “hydrogen economy”.

FPC’s system provides the essential requirement, high temperature heat. The high temperature heat allows efficient hydrogen production
either by 1) a thermochemical process, or by 2) high temperature electrolysis with electricity that is generated efficiently.

Economically providing hydrogen, heat, and electrical power, FPC’s system can provide the cleanest and greenest  alternatives for liquid fuel production and smooth the insertion of fusion power into the energy supply.

  Production of Synthetic Fuels

We generally think that fusion power plants will be sources of electricity, but in reality their output is heat some of which will be used to produce electricity. FPC's StarPower System (SPS) will also produce electricity, but electricity will not be the only product, and may not be the primary product. The availability of very high temperature heat permits the consideration of another process of energy conversion and that is the direct production of hydrogen from the thermal disassociation of water. The known, and well researched, Sulfur–Iodine process and the high temperature electrolysis process both produce hydrogen at about 50% efficiency.

Hydrogen is the key component in the production of synthetic fuels and can be produced from SPS systems at a cost comparable to the cost of production from reforming of natural gas.  The hydrogen can be used directly as a fuel source or it can be combined with carbon to form various hydrocarbons including gasoline, kerosene (jet fuel), or diesel oil.  Since these latter fuels support the existing transportation infrastructure, are transportable and storeable, we intend to focus our hydrogen output on production of these synthetic fuel products.

The source of carbon can be biomass, or coal, or the CO2 in the atmosphere. Evaluation of the technology for extracting CO2 from the atmosphere by the Los Alamos National Laboratory concluded that this technology is now mature enough that it is viable as a source of CO2. Since we have to dispose of waste heat in any case, why not use the waste heat to drive a cooling tower that processes a large volume of air and extracts the CO2 from it?  Carbon from an atmospheric source is slightly more expensive than carbon from coal, but the use of atmospheric carbon means that the liquid fuel we produce would become carbon neutral – the carbon comes from the atmosphere and returns to the atmosphere again when the fuel is consumed.

The processes for conversion of hydrogen and CO2 to form synfuels is a mature industrial process that has been used by Exxon-Mobil in the past and is currently being used by Sasol to produce liquid fuels in plants in South Africa and Arabia.  Until now, the constraint for the production of synthetic fuels has been the availability of an inexpensive source of hydrogen.  The heat from an SPS will remedy this shortcoming and make the synthesis of liquid fuel possible at a cost less than the current cost of the same fuel from a crude oil feedstock.

  Economics and Ecology

Liquid fuels have been synthesized from coal for nearly a century. Natural gas also is converted to liquid fuel. Converting a fossil fuel to a different hydrocarbon does not avoid the emission of greenhouse gases, often increasing them. Nor does the process mitigate the environmental effects of resource extraction. Ultimately, transitioning from oil to coal or natural gas for transportation fuels is a transition from one inherently limited geological resource to another.

In principle, liquid fuels from biomass are “net zero” emitters of CO2. However, the cost of transportation of the biomass to a central major facility such as an SPS facility rapidly make the economic value of the biomass negative.  Thus biomass Carbon is not a very likely source for our liquid fuel process.  

Coal is a viable source of Carbon for synthetic fuels and this was the source initially used by SASOL.  But coal is a fossil fuel and thus its use to make synthetic fuels would make the product non-green. 

The greenest kind of source of liquid fuel would use heat and Hydrogen from a green source in a chemical process that combines the Hydrogen with CO2 extracted directly from the atmosphere. FPC’s system provides the clean, economical, and large scale source of hydrogen and heat. With FPC’s system, the chief questions about this greenest means to provide liquid fuels concern the economics of extracting the requisite quantity of CO2 from the atmosphere. Current CO2 sequestration research supports our contention that this process is economically viable.

  Hydrogen Production

Most hydrogen is produced today by “reforming” natural gas, a fossil fuel. Electrolysis is a well-known source of hydrogen. Electrolysis is green if the electricity source is green, but the hydrogen is more expensive than that from natural gas due to summing the cost of the electrical energy and the costs of the electrolyzer.

A more recently developed process separates hydrogen from water “thermochemically”.  As this figure shows, the potential for highly efficient conversion
of heat energy to latent chemical energy in hydrogen depends on having
a heat source that provides temperatures above 900oC. By avoiding the cost of electricity for electrolysis, the thermochemical process may lower the cost of hydrogen. And requiring only heat and water inputs, the process will be green if the heat source is green. 

Conventional fission reactors do not reach the temperature needed for the thermochemical process, which also limits the efficiency with which they generate electricity. Although the high temperature gas-cooled reactor (HTGR) might meet the temperature requirement, the HTGR has not been commercialized despite decades of development, and the problem of nuclear waste remains. 

Uniquely among fusion systems, FPC’s chamber system
provides the high temperature heat required for the thermochemical process—while also solving or avoiding problems facing other fusion chambers, even though they produce lower temperature heat. By the same token, however, FPC’s high temperature also increases the efficiency of electricity generation.

  FPC Balanced Strategy 

Ultimately, the issue will be determined by economics. Energy supply is capital intensive, and choosing the technology to use involves placing large bets. The practical issues are about the materials and costs associated with the different processes for making hydrogen and liquid fuels. The high temperature heat from FPC’s system can support the best of the processes.

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Jun 14, 2011, 4:09 PM