Feb
16
Biomass to Gasoline On the Cheap?
February 16, 2011 | 5 Comments
Steven D. Phillips has led a team at the National Renewable Energy Laboratory (NREL) with a claim from their study of making gasoline via the methanol-to-gasoline (MTG) route using syngas from a 2,000 dry metric ton per day (2,205 U.S. ton/day) biomass-fed facility for unit sale price of prices for gasoline at $1.95/gallon ($0.52/liter) and Liquid Petroleum Gas at $1.53/gallon ($0.40/liter). That’s only 7¢ more than this writer paid just last week for LPG – delivered.
The study relies on the Exxon Mobil developed process where syngas is converted into methanol, and the methanol is converted to gasoline using the methanol-to-gasoline (MTG) process.
This is all well and good but the authors seem to be missing some major inputs and the variations those might have on the precepts used. It all hinges on getting landholders to deliver the biomass. That entails competing with other income types and earning out the investments and costs for the biomass gate price. In the NREL study these issues are considered but not thought through. We’ll come back to that.
NREL Biomass to Gasoline Process Graph. Click image for the largest view. Details begin at page 13 in the paper.
Feedstock matters aside, the study group has done an admirable job of working up an Excel spreadsheet story. For those who’ve worked with Excel, choosing the assumptions and laying in the formulas can be magical. But is it real?
The engineering looks fully real. Simply put the flow is biomass in, dried and cut fine for the following gasification step. Then the gas is cleaned up and conditioned. The cleaning and gasification steps send back their heat and flue gases to the biomass drying effort.
Cleaned and conditioned gas is then synthesized into methanol, which is then conditioned, and sent on to the Exxon Mobil process. The products of gasoline and LPG are separated and ready for sale. Sounds all rather simple, and it is until you engineer it.
NREL Biomass to Gasoline Block Flow Diagram. Click image for the largest view. Explanatory text at page 17 and Appendix H of the paper.
But all the steps are conventional processes in use today. They just haven’t been assembled such that the feedstock and products proposed enter and exit the same plant. Functionally speaking, this will work, but that’s been known for years.
What is new are those assumptions in the Excel spreadsheet and the formulas chosen. Here’s the problem in the simplest terms: The plant would need 2,205 tons of dry biomass per day and produce just over a million barrels of gasoline per year. The assumption is to pay just over $50 per ton dry – or at 50% moisture by weight the price may be closer to $35. Someone has to pay to drive off the water before gasification, and it isn’t a cheap part of the process.
So assume the landowner or farmer is going to consider the proposal to commit to growing the proposed poplar tree crop. The Minnesotans have worked up poplar as a crop. They expect the optimal very best land and plants could get to 6 tons an acre per year or about $300. Realistically the research suggests it’s more like 3.5 tons or $175 per year. That’s gross income, mind you. Now what might happen in the southeast U.S. is up for more research, but the gross revenues, after agronomy costs of the plant, the weed control, fertility, plus the equipment, wear and tear, manhours, fuel costs and interest expense and some profit – there’s not much there to work with. A corn acre at the U.S. average 155 bushels per acre selling at $4 produces $628 and yields nearly 400 gallons of ethanol.
The NREL study expects to get a bit less than 53 gallons of gasoline per ton of poplar, or at the multiple of 3.5 some 185.5 gallons of gasoline per acre per year.
Even when you discount the ethanol for BTUs, corn and sugarcane ethanol look very good indeed. In addition, sugarcane remnants are useful and corn’s important oil, fiber and protein components remain for sale providing for the high value food markets.
That $175 per acre per year doesn’t look like enough, actually far from it. The NREL study could work, at gunpoint for the landowner. Which considering that the U.S. Supreme Court held in effect that government units can seize land for private use – it’s a possibility.
On the other hand . . . if one were to choose a crop more at the 10 tons per acre per year on non prime land a $500 gross might happen for the landowner – that might work. But keep in mind there will be 220 acres clear-cut at 10 tons per acre and 630 acres clear-cut at 3.5 tons, nearly a square mile per day. Every day 365 days per year. It’s a square over 25 miles on a side each year, about a county in size. Yields have to go way way up. Either assumption requires industrial size, large manpower inputs and substantial transport for the biomass.
Now you know why the oil companies aren’t spooked by biomass and irritated by corn and sugarcane ethanol.
But there are ways to amplify the results. Stop the processing at methanol and use it in a fuel cell.
The NREL study managed quite a lot of attention from press release distribution. It’s really a pity the numbers don’t work. The authors even note that some of the assumptions were obtained from previous work. A taxpayer might think the team could find a more productive use of the manpower.
For biomass to work the productivity per land area has to be massive, 10s of tons per acre. The concentration of sugars and starches is already known in the sugarcane and corn crops. Making the jump to biomass, even with a highly efficient conversion to fuel requires lots of land area unless the production is huge.
Bio oil production, algae, seaweed and others offer much more revenue per acre. That’s the metric that comes first, can the investment made under the sun be made to pay?
That’s the tough question most folks overlook.
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Exactly.
The mass of biomass per acre must be massive, so to speak.
Gasification doesn’t care about lignin vs. cellulose / hemicellulose. It takes it all apart regardless, using significant energy resources.
Researchers have to get clever from both ends to make the yield efficient and economical.
The growth end provides much room for improvement, using genetic engineering and symbiotic organisms.
The industrial process end likewise offers room for innovation, although perhaps not quite as much.
Between both ends is the harvesting, transport, and pre-processing stages, which could also be better.
And then there are always more ends to the ends . . . many of which rest on imagination, planning, and disciplined thinking, to say nothing of motivation.
Municipal waste contains a very large fraction of biomass, and yard waste pickup even more. The materials are delivered to singular collection points. Perhaps enough fuel could be generated to run a fleet of city vehicles?
JP Straley
A few years ago, Pine sold for ~~$7/ton (50% water wet) in the southeast….Delivered ~~50 miles at ~~~$14 per ton (50% water wet)
Where did you get $50/ton?????
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My consortium has alternate biomass yielding ~~~$40/ton-acre-year.
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There are alternative proprietary processes with higher yields.
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George
BS ChE
Chemical Engineering and Process Control
Projects: Design/Construction/Maintenance/Troubleshooting in 10 countries and 10 US States.
Pulp-Paper, Power, Petrochemical, Refining, Oil and Gas Production with relatives and friends in agriculture and business.
The biomass to gasoline/hydrogen problems are not land and processes to be selected.
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The real problems are ridiculous regulations.
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My consortium would move in a massive way now with certain changes in regulations such as all required environmental design changes should be 100% deductible from federal taxes,
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and reasonable cost for biomass and oil companies to use trash land owned by the govt.
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Additionally, our rough estimates are that a $450 billion dollar investment by oil and biomass (and certain other) companies would yield exporting of ~~~$1.3 Trillion / year of synthetic gasoline and other liquid fuels to be able to move $1 Trillion of our debt back to the USA.
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