How is this process different from other competing and similar technologies and projects, many of which have failed in the past and which are failing today?
The Raven SR process is fundamentally different in that it is a chemical, rather than a combustion process. The fact that the Raven SR technology is non-combustion increases efficiency, allows for a wider range of feedstock, and eliminates many of the problems faced by gasification and Fisher Tropsch (FT) projects in the past, as discussed in the following questions.
Raven SR is similar to companies such as Fulcrum Bio-Energy, Sierra Energy, RedRock Bio-Fuels and Grey Rock in that there is fundamentally a gasification process to create a syngas. However, Raven SR’s patented steam CO2 reformation process creates a syngas that is twice as rich in hydrogen as competing technologies, enabling the production of higher quantities of renewable hydrogen or FT fuels without the maintenance and other issues caused by combustion.
Raven SR is currently focused on hydrogen production from waste. The technology’s ability to produce hydrogen from various waste streams is well established and documented, and the pilot unit is continually producing hydrogen at this time. The market for renewable hydrogen in California is growing, and Raven SR can produce renewable hydrogen at a lower price than any competitor in the market.
With respect to the Fisher Tropsch, Raven SR is currently filing new patents on modifications to the traditional FT process, increasing efficiency.
Is your steam reforming process a type of gasification process?
Yes, our “Steam/CO2” reforming process is a subset of the broader class of gasification processes. In our case, we do not use oxygen, which is more common in oxygen-blown gasification processes for coal and petroleum coke.
Describe the difference between “gasification” and “Steam/CO2 Reforming.”
This is a key difference between the Raven SR process and other processes – Gasification uses combustion, while Steam CO2 reforming does not. Gasification is very different chemically and thermodynamically from “Steam/CO2” Reforming. While both processes require heat to drive the endothermic chemistry, the source of that heat is significantly different with considerably different results.
Combustion is defined as “any process in which a substance combines with oxygen to produce heat and light.” [Oxford Dictionary of Chemistry] or “Burning (rapid oxidation) of fuel, which releases energy in the form of heat and light, and also releases pollutants (such as sulfur dioxide, nitrogen oxides, and particulates).” [Oxford Reference: A Dictionary of Environment and Conservation]
The Competition Process:
In gasification, heat is generated by combusting part of the feedstock, making CO2, which then dilutes the resulting syngas by reducing the amount of H2 that is produced. That combustion also consumes part of the syngas further reducing the H2. This type of gasification is called “Autothermal Gasification,” since the heat is supplied from inside the process and does not use heat from the outside. In addition to hot-spots and/ or creosote buildup typical of gasifiers, the high temperatures will often melt glass and some metals, creating slag and makes disposal of the resultant ash, a significant problem. In most cases, this combustion is driven by adding air, that further dilutes the H2 by the presence of nitrogen. This combustion also generates various side reactions contaminating the syngas with particulate soot, oxides of nitrogen and sulfur and even makes dioxins and dibenzofuran, both of which are carcinogenic. Environmental and political stakeholders classify this autothermal gasification as incineration, which makes siting very challenging, if not impossible.
In gasification, the practice of using pure O2 is expensive and only justified with large scale plants where a liquid oxygen plant on site is justified. While using pure O2 eliminates the N2 dilution, it does nothing to eliminate the nasty bi-products of combustion from dirtying the syngas which in turn harms catalysts in the Pressure-Swing-Adsorption unit and/or the Fischer-Tropsch reactors – reducing efficiency and increasing costs. Additionally, gasification requires moisture levels typically to be under 10% which requires expensive drying processes at the first stage of the process.
Raven SR Process
Our patented “Steam/CO2” Reforming process is very different and a significant improvement over gasification. In “Steam/CO2 Reforming,” the term of our patented chemistry, there is no oxygen or air (i.e. 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases) added – it is actually evacuated from our process so there is zero combustion inside our rotary reformer. For this reason, the California EPA has determined that the Raven SR method is a non-combustion process (cf. 22 CCR § 66260.10 Definitions and 40 CFR § 260.10 Definitions).
We supply all the needed endothermic heat from sources outside of the reformer by recycling waste heat and/or electrical heat up to 1,200°F. We can also control the temperature gradient along the axis of the rotary reformer from 300°F at the front up to 1,200°F at the exit end. This permits us to control the rotary reformer when there is water content or chemical makeup variation in the feedstock, such as in MSW. Careful temperature control prevents melting glass and metals from melting and becoming slag, and produces a biocarbon which is a salable product. As a non-combustion process, there is no ash, no slag, build up, or hotspots in the equipment.
We can also add small amounts of CO2 to adjust the H2/CO ratio in the process that is needed for FT fuel production. “Steam/CO2” reforming makes a much cleaner syngas with contaminates less than 1 ppm so that the catalysts in the Pressure-Swing-Adsorption unit and or the Fischer-Tropsch reactors are not at risk from poisons and run longer and more efficiently. Additionally, high moisture content (~50%) is an advantage for “Steam/CO2” processing and is near where most MSW is in a natural state. Finally, the process does not produce any of the siting issues associated with incineration/gasification projects.
What can you process?
We can process a wide range of waste, from municipal solid waste to industrial waste, raw sewage, medical waste, creosote contaminated wood, animal waste and carcasses, bio-waste, such as wood chips or agricultural waste – the list goes on (see table below). We can also process natural gas and theoretically coal. Regarding metals, we cannot process these into fuel, however, metal will drop out of the steam reformer, and be sterilized and disposed of or recycled. A high metals content impacts the use or disposal of our biocarbon (15% of process weight,) therefore, any removal prior to “Steam/CO2” reformation protects that aggregate which can then be sold as a valuable carbon source.
To what extent is segregation of incoming waste feedstock necessary? What about water content and other impurities?
Generally, sorting and shredding of MSW/medical is used to remove high-value recyclable materials (i.e. glass, aluminum, etc.) and we assume a working relationship with a waste-management system, such that these costs are carried by them.
Unlike gasification, the high moisture content (50%) is an advantage for us and is near where most MSW is in a natural state. Our process is steam reformation, therefore we would not need to dry the feedstock, and in some cases would add moisture if our feedstock is less than 50%. The gasification processes, on the other hand, requires moisture levels typically to be under 10% which means they must dry feedstocks prior to combustion at a significant financial cost.
Inorganics salts have no effect, but HCl at high levels could, with PVC plastics, etc. The syngas would then be cleaned to ppm levels of sulfur to extend the FT catalyst life.
A high metals content impacts the use or disposal of our biocarbon (15% of processed weight), therefore any removal prior to “Steam/CO2” reformation protects that aggregate which can then be sold as a valuable carbon source.
Is a feedstock prep necessary?
To a degree, yes. We can process nearly any feedstock as seen above, but certain feedstocks pollute the bio-carbon residual that drops out during the first stage of our rotary reformer. Aluminum cans, for instance, can go in, but we do not necessarily want aluminum mixed in what should be a pure bio-carbon aggregate. Therefore, a pre-sort removing high-value waste (e.g. aluminum, iron, etc.) and dropping out concrete and rocks will allow for a purer bio-carbon at the end of stage one. Our rotary reformer consists of a commercial “calciner” that is hot, free of oxygen and involves a slanted and rotating tube capable of handling large size pieces (up to 2-3 cm). As the waste moves from shredder to the rotary reformer, all free oxygen is removed through a CO2 bath inerting the waste so that no incineration or combustion takes place. (See the difference between gasification and Steam/CO2 Reforming above.)
How big are the units?
The units are approximately the size of two 40-foot containers, plus a distillation column. The units are modular, allowing plants to increase or decrease depending on feedstock supply or product demand.
Are any harmful gases or by-products released in the process?
There will be small amounts of CO2 released, as is inevitable in any process, but we recycle most of the CO2. Air emissions are 2.5 times less than the best available technology, and the process itself has passed California emissions standards.
Are catalyst licenses needed for hydrogen production (the water gas shift reaction) or and for the Fischer-Tropsch syn-fuel process variants?
If this process is such a good idea, then why didn’t someone think of it before?
Steam reforming dates back at least 120 years. It was explored long ago for coal, and later for oil conversion, to produce a gas intended for illumination. The syngas produced at that time contained organic contaminants and had limited commercial applications. With today’s high-temperature alloys and high-tech ceramics, this chemistry was re-examined by Raven SR and new patents were issued which demonstrates how to carry out steam reforming at high temperature and with the proper amount of steam and CO2 to produce a clean, rich syngas.
If this is so great and has been around for so long, why hasn’t it taken off before now?
Intellergy, Inc., where the technology was developed, was created with a focus primarily on waste elimination, rather than monetization through the creation of fuels. The company sold numerous systems to nuclear power plants and operated a toxic waste elimination facility for the pharmaceutical industry for some time. Typically, these units were sold or spun off. In the mid-2000s, the company entered into a commercially disadvantageous agreement, which stifled growth and prevented development for several years. In 2015, the owners of Raven SR began funding development again, and in 2018, Raven SR acquired the patents of Intellergy.
How is this different from, or better than, pyrolysis?
Plastics pyrolysis is a process of converting specific plastics back into petroleum products. Pyrolysis can use only specific plastics, and the quality of the fuel produced is vastly inferior to FT fuels, and it cannot produce renewable hydrogen.
How is this different from bio-fuel technology?
Biofuel projects typically rely upon specifically grown crops or specific agri-based feedstocks. The Raven SR technology is different in that a) it can utilize a wide range of feedstocks, b) it can use waste, including plastics and medical waste, for which a tipping fee may be obtained, c) the system can produce either 99.9999% pure hydrogen, or synthetic Fischer-Tropsch fuels, which are cleaner than petroleum or bio-based fuels.