Krebs & Sisler LP Receive Patent for Recycling Carbon Dioxide (CO2)


CHICAGO--()--Krebs & Sisler LP, a suburban Chicago energy research firm, has developed a low-cost CO2 separation and recycling method called Enhanced Photosynthesis and Photocatalysis Water Treatment/Biomass Growth Process. It is described in U.S. Patent No. 8,673,615 granted March 18, 2014. It neatly complements the O2/CO2 combustion and condensing boiler system of our U.S. Patent No. 6,907,845 which separates and recovers CO2 and all other combustion-generated exhaust gases.


“We discovered economical CO2 recycling in the finding that hydroponic biomass growth can be increased more than 100 times the natural rate by continuous CO2 infusion and simultaneous LED visible light saturation. This improvement is outlined in the 8,673,615 patent,” stated inventor Bill Krebs.


In O2/CO2 combustion, oxygen is diluted with CO2 for temperature control of the fuel oxidant used to combust coal, petroleum coke or natural gas. Excluding the nitrogen that is present in air-fired combustion enables cost-free recovery of both the condensate and the CO2 from a condensing boiler. The condensate and CO2 are pumped into deep and slowflowing water channels, saturated in the visible light spectrum of light-emitting diodes (LEDs). A photocatalyst mineralizes organic and inorganic compounds for absorption into a cynobacterial biomass like Spirulina. The absorption of minerals in the growing biomass concurrently purifies the flowing water. These processes when optimized will reliably operate at high efficiency with no harmful emissions or effluents into the environment. They will also produce a carbohydrate and protein-rich biomass useful for fuel, fertilizer, animal feed or a human food supplement.


“We are now developing a combination coal, rotary kiln, O2/CO2 combustion condensing boiler. It will have significant cost, efficiency and emission advantages,” Krebs explained. “A critical factor for heat transfer efficiency is that the crushed coal rotary kiln method of combustion allows three to five minutes or more for complete fuel-burn and heat-transfer time, whereas the pulverized coal combustors presently in use allow only three to five seconds.” Krebs continued, “Today’s air-fired plants operate at an average 34% fuel efficiency. Our O2/CO2 combustion method, when combined with a condensing boiler, can more than double plant fuel efficiency and thereby reduce both the fuel and oxygen requirements by half.”


“The many applications and advantages of this combination of processes include the conversion of waste CO2, wastewater and saltwater to profitable biomass and demineralized drinking water, improved electric power production efficiency, virtually no harmful emissions, relatively low capital and operating costs at large scale, improved fuel flexibility, improved revenues and compact use of space compared to presently operational electric power production methods which waste CO2, heat and water vapor into the atmosphere,” summarized Mr. Krebs.


“Sequestration has been proposed as a method of disposing of CO2, but it is expensive and wastes carbon and oxygen, two elements essential for life on Earth,” Mr. Krebs noted.


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Krebs & Sisler LP
W.P. Krebs, 1 312-236-9724


View our May 14, 2014 press release, "Krebs & Sisler LP Receive Patent for Recycling Carbon Dioxide (CO2)" in:


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CO2 Desalinization

Hydroponic Photosynthesis

Large scale salt water desalinization will be most economical when large amounts of relatively pure CO2 are continuously available at low cost for a hydroponic biogrowth process using specific algae which require CO2 for growth.   These are autotrophic cyanobacteria microalgae such as the species Spirulina.   Best growth rate results will be achieved when the amounts of CO2, light and balanced nutrients are optimized for flows at ambient temperature and near-neutral pH.   As they grow the algae absorb any minerals in the water.   The harvested algae biomass, when dried, is a useful fuel containing 50% carbon.   Or it may be used as an animal feed supplement and human nutrient rich in proteins (60%), carbohydrates (20%), and vitamins A, B, and E.

Sourcing Low Cost CO2

CO2 desalinization at large scale will require hundreds to thousands of tons of CO2 per 24 hours, therefore the best siting will be near large power plants fueled by hydrocarbons and biomass.   Separating high purity CO2 from the flue gases of state-of-the-art power plants is extremely expensive; so it will be preferred to adopt the new high-efficiency closed-cycle O2/CO2 combustion system detailed in U.S. Patent No. 6,907,845.   Due to it's unique condensing boiler, the exhaust gas output of this system is better than 95% CO2 without further processing as shown in Table 1 of the patent.

 Combining Photosynthesis and Photocatalysis 

Hydroponic photosynthesis for algae growth is coupled with photocatalysis for water purification in a closed all-weather continuous process.   Photocatalysis shares the light available for photosynthesis and breaks down organic and inorganic compounds including toxins for mineral absorption by the algae.   The method yields a highly cost-effective synergy of this combination.   It is detailed in our pending patent entitled "Enhanced Photosynthesis And Photocatalysis Water Treatment/Biomass Growth Process".

The water treatment is continuous in enclosed cells.   Consider for example an estimated flow rate of 15,000,000 gallons per 24 hours through a series of four cells on two acres.   At this scale and assuming 100% CO2 absorption in the algae biomass, it is expected that at least 100 tons and possibly 1,000 tons of CO2 per 24 hours may be converted to biomass for harvesting from the desalinated potable water.   Processing salt water to potable water by this means is estimated (in 2010) to cost $1.00 per 1,000 gallons ($0.25 to $0.30/m^3) if high purity CO2 is available free to the process, as from an adjacent O2/CO2 combustion power plant.

The combination of clean water and power production is potentially a zero emission system except for nitrogen released from the air separation unit (for O2/CO2 combustion) and oxygen released from water treatment if all CO2 is absorbed in algae photosynthesis.

by Krebs & Sisler L.P., copyright August 2010

View our September 13, 2010 press release, "Krebs & Sisler LP Announces a New CO2 Water Purification Method" in:


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In the news:


"New Biochemical Process Halves Water Purification Costs" by UPI


"Water Purification Method Harnesses CO2 from Captured Carbon" by Science Business


"New CO2 Water Purification Method Developed" at WaterWorld