Circular scale: T2C finds a path to feedstock-scaled renewable diesel from biogas

August 17, 2020 |

A new technology has arrived in South Florida for the conversion of biogas to diesel fuels. If you thought of this as a biogas-to-paraffins technology, that would be fine, too. But it’s not strictly a methane-to-paraffins technology, because this technology from T2C also utilizes the CO2 stream found in biogas.

The biggest problem, in terms of US sites? Yes, there’s 800,000 standard cubic feet per minute of biogas, representing the equivalent of 3.7 billion gasoline gallons. At 2,451 landfills, 1,241 wastewater anaerobic digester (AD) facilities, and 282 agricultural AD facilities. Yet, 85 percent of facilities produce less than 4 standard cubic feet per minute. The feedstock is devastatingly decentralized.

Two other problems?

1. Different feedstocks present challenges for digesters.

2. The conventional products for biogas are heat, power and CNG for fuels — they are becoming saturated and more of a buyer’s market based on low commodity prices. It’s getting hard to find CNG vehicles that aren’t using bio-CNG already, and competition from cheap wind and solar muffles the demand for electricity. Heat is still viable, but that can restrict geography.

A number of technologies address landfill as a source of feedstock for liquid fuels — that’s what Velocys is working on in the UK and elsewhere and Fulcrum BioEnergy is too, in several US projects. Yet, those projects are aiming for scales that dwarf the supply available from, say, a digester atop a local dairy.

Enter T2C, which has licensed the TRIFTS technology from the University of South Florida and is now developing it. T2C describes it elegantly: The heavy equipment and waste hauling trucks can therefore unload and refuel at the same landfill or AD site with a renewable diesel fuel derived from the very waste they hauled. That’s circular scale, not just circular technology.

The technology at a glance

A useful summary can be found in Sustainable Energy & Fuels, here:

Tri-reforming of such biogas (CH4 + CO2) is a combination of dry reforming, steam reforming, and partial oxidation to produce syngas (CO + H2). This syngas can be converted to liquid hydrocarbons using Fischer–Tropsch Synthesis . A novel technology of combining tri-reforming and FTS (TriFTS) is proposed and utilized to convert landfill gas to high value added liquid hydrocarbon fuels such as gasoline, diesel, and jet fuel. 

After removing contaminant gases such as H2S and NH3 via condensation and adsorption, NiMg/Ce0.6Zr0.4O2 pellets were used in a tri-reforming reactor to produce H2 and CO in a ratio suitable for FTS. The conversions of CH4 and CO2 were 99% and 60%, respectively. The H2/CO molar ratio was 1.7. In the FTS section, a Co/SiO2 eggshell catalyst was used to synthesize liquid hydrocarbon with high selectivity for middle distillate cuts. The CO conversion in FTS was 71% and the liquid hydrocarbon product was similar to that of low sulfur diesel. The experimental results were used to conduct a preliminary economic analysis of a commercial scale TriFTS process. The results indicate that 45% of the energy contained in the LFG can be recovered in the liquid fuel generated, with the rest going to meet the energy demands of the conversion process including heat losses. 

The breakeven cost of diesel fuel produced was estimated as $3.24 per gal but reduces to $2.71 per gal if the LFG is assumed to be free of cost as would be the case for landfill operators. Additional renewable fuel credits will make the process even more economically attractive.

This study suggests that conversion of LFG to liquid fuels is a promising new technology ripe for commercialization.

The biggest challenge to this industry is its largely decentralized nature. Existing biogas projects include direct heating, electricity generation, and enrichment of methane for pipeline use or for NG-powered vehicles. T2C-Energy has developed and patented a novel catalytic technology we have trademarked TRIFTS for the direct conversion of biogas to drop-in transport fuels.

A previous T2C-DOE collaboration

T2C had previously collaborated with the US DOE to build a mobile pilot facility for the purpose of testing the technology onsite at multiple landfills and AD’s. The unit was designed to convert a 9-24 scfm slipstream of raw biogas into renewable transport fuel.  Long-term testing would be carried out at the Citrus County Landfill, in Lecanto, FL. If you’re a golf fan, that’s about a mile and a half south of the legendary Black Diamond Ranch, if fishing is for you, it’s just east of the Crystal River/Homosassa saltwater sport fishing mecca.

The new project

A new project is focused on optimizing this new TRIFTS technology at a relevant engineering scale capable of utilizing both the CO2 and CH4 portions of biogas and incorporating them into the hydrocarbon backbone of the final product of the process (renewable drop-in diesel). This project focuses on rigorously testing our TRIFTS technology at the engineering scale to convert a diverse range of biogas feedstocks derived from MSW, wastewater, animal waste, food waste, and crop residues into high quality renewable, drop-in diesel fuel.

So, the challenge of different compositions and impurities is at the heart of this. Also, the catalytic parameters, process dynamics, system performance, process LCA, and fuel product quality will all be monitored and studied over sufficiently long term periods (over 500 hours per site) in order to optimize efficiency, productivity, and economics of the TRIFTS process and incorporate into the scale up of TRIFTS plant designs.

The DOE writes:

The pilot technology would be composed of a number of different biogas, air and water feed devices (e.g. compressors, heaters, and supply tanks), reactor devices, and processing equipment (e.g. de-pressurizer, output storage tanks). The equipment would be joined together to form a self-contained, modular unit. This unit would fit onto and be transported via a 53’ x 8’ x 11.5” skid mounted on a single drop deck flatbed trailer. Additional equipment would be transported using a 15’ x 7’ x 7’ utility trailer. The pilot unit would be connected to existing biogas collection systems at existing wastewater treatment and landfill waste facilities where testing would be performed (discussed further ahead). This would be achieved via a single 1.5” polyethylene pipe. Electrical power would be provided either by establishing a grid connection at the sites that receive grid power, or by a diesel generator in cases where grid power is not available.

The pilot unit, once connected, would process biogas collected from the existing collection system at each pilot site. Liquid fuel (e.g. TRIFTS derived jet/diesel and off-road diesel) would be produced as the end-product of the demonstration process. The addition of the pilot unit would not affect existing operations at the pilot sites, as the biogas that would be collected for processing would otherwise be flared as part of standard operating procedures.

Task 1: Process and Data Pre-Verification

Task 2: Pilot Scale TRIFTS Testing

Task 3: Data Analysis and Lab Testing

Task 4: TRIFTS Long Term Studies – Long-term pilot testing (i.e. more than 1000 hours) would be performed. Over 100 gallons of drop-in diesel would be produced as part of this testing.

Our Multi-Slide Guide to T2C

You can find it here.

The Bottom Line

Long way to go for this one. There’s the pilot, then there’s a lengthy demonstration, the offtake contracting, the feedstock sourcing, the LCA analyses, the pathway approvals.

But there’s a real bombshell in those financials and the technology overview. At last, a technology scaled to this feedstock. That’s been a trend — QCCP and others have developed feedstock-scaled cellulosic ethanol from corn fiber. NextChem and Saola have partnered on feedstock-scale renewable diesel from corn oil. Those have been lost feedstocks, but not exactly waste. Now, here’s a technology that addresses landfill, and no one opposes bioconverting landfill to useful products.

And look at those prospective figures — a break-even at $2.63 per gallon excluding RINs and LCFS credits — which can add more than $3.00. We’ll see how that holds up as the technology scales up. But it’s a value that attracts attention, and T2C is one to watch.

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