Turning CO2 Emissions into Fuel

Process combines carbon dioxide, water and lignin into syngas.
By Gary C. Young | September 21, 2016

A new process for the economical conversion of carbon dioxide into fuels such as ethanol has been developed. The proprietary noncatalytic process combines CO2 with a carbonaceous feedstock and water in the form of steam at temperatures between 1,600 to 3,000 degrees Fahrenheit and low pressure, near atmospheric, in a gasifier to produce a syngas comprised mostly of carbon monoxide and hydrogen.  The syngas can be converted to a fuel such as ethanol via a commercially available biochemical process.  

The over-all process using Bio-Thermal-Energy Inc.’s technology for the conversion of CO2 emissions from a cellulosic ethanol plant to more ethanol is a process in which lignin is the carbonaceous material.   Both carbon dioxide and lignin are byproducts produced from the corn stover-to-ethanol plant. A cellulosic ethanol plant with a capacity of 25 million gallons per year of ethanol produces enough CO2 emissions for another 21.3 million gallons of ethanol annually using the technology, with the combined plants profitable.

B-T-E’s proprietary process has six U.S. patents, one Japanese patent and other patents pending. The technology was proven experimentally at Westinghouse Plasma Corporation’s 12.5 ton-per-day pilot plant in Pennsylvania. Syngas was produced in the pilot plant using a feed comprised of CO2, steam and a carbonaceous material.

As a noncatalytic process, the carbonaceous material fed to the high-temperature gasifier can use flexible feeds such as gases, liquids, solids or a mixture. Furthermore, a wide variety of carbonaceous feedstocks can be used including corn stover, wood, switchgrass, lignin, municipal solid waste, methane, coke, carbon black, coal, charcoal or tires. The CO2 feed from a corn stover-to-ethanol plant does not require any purification and crude lignin from the plant can be fed to the CO2-to-ethanol plant, without costly drying or pelletizing operations. 

Economic Analysis
The economics for the conversion of CO2-to-ethanol was established for a system in which the CO2 and lignin were byproducts from a 25 MMgy corn stover-to-ethanol plant, and therefore considered as waste byproduct with no cost. The typical economic case for a CO2-ethanol plant indicates a production cost of 98 cents per gallon for the ethanol with an estimated production of 21.3 MMgy.  Natural gas cost was figured at $2.80 per MMBtu and electrical cost of 5.5 cents per kWh. Total capital expense projections include ISBL (inside battery limits) and OSBL (outside battery limits) with OSBL at 50 percent of ISBL, which is typical of a greenfield plant.

Using an ethanol selling price of  $1.458 per gallon (Chicago Board of Trade, July, 2016), net annual revenue is $10.18 million. (21.3 MMgy x $1.458 per gallon minus 21.3 MMgy  x 98 cents per gallon equals $10.18 million per year).  Total CAPEX is $176 million, or $8.26 per gallon of ethanol. The payout is 17.3 years with no subsidies.

A similar case was considered but with OSBL at 25 percent of ISBL, which would be typical for a CO2-to-ethanol plant integrating operations with the corn stover-to-ethanol plant.  Total CAPEX becomes $146 million, or $6.85 per gallon and the production cost is estimated at 86 cents per gallon, for a net annual revenue of $12.74 million and an 11.5-year payout. In the economic analysis, operations are considered at 8,760 hours per year, total CAPEX includes ISBL and OSBL, capital at 6 percent and 20 years, OPEX-operation expense includes labor and maintenance, CO2 conversion rates to syngas of 65 to 70 percent based upon experimental data, and no subsidies. If renewable identification number (RIN) credits are included the economic analysis improves substantially. Late July D6 2016 corn ethanol RINS were valued at 96.5 cents per gallon and 2016 year D5 RINs (for other advanced biofuels) were $1.015 per gallon.

B-T-E has spent about 10 years in the development of the patented CO2 conversion technology to syngas (CO & H2) and potential commercial applications.   Originally, thermodynamic computations by Dr. Gary Young of Bio-Thermal-Energy Inc. determined that CO2 could be converted into syngas with a carbonaceous material and steam at proper process conditions using gasification.  B-T-E has continued development of this novel proprietary technology which has shown to be a game changer for the ethanol industry.

B-T-E’s current business plan is to have a technical and economic feasibility study done at a cooperating cellulosic-to-ethanol plant using B-T-E’s CO2 technology to convert the byproducts CO2 and crude lignin into ethanol. Of particular interest would be to select a plant site that is representative of the cellulosic ethanol industry and is suitable for a feasibility study to determine overall CO2 reduction from cellulosic-to-ethanol plant stack gas to final tail gas in the CO2-to-ethanol plant, and determine economics.

If the feasibility study demonstrates profitability and promise, the next step will be a pilot project. Such an approach would benefit both the cellulosic ethanol industry and U.S. environmental regulatory agencies.  It is a win-win proposition created by novel technology for all to benefit through jobs creation, more profitable cellulosic ethanol plants, positive environmental impacts and by promoting U.S. energy independence.

Author: Gary C. Young
President, Bio-Thermal Energy Inc.