Switchgrass harvest

Much of our gasoline contains up to 10% ethanol. The ethanol comes from the sugar in corn. It takes a lot of energy and petroleum-based fertilizer to grow the corn. As it turns out, this ethanol yields less energy than it takes to make it. Is it possible to get ethanol from cellulose, using non-food crops that grow without fertilizer and irrigation?

In 2006, President George W. Bush began to promote making ethanol from switchgrass. But deriving ethanol from cellulose requires a more complicated and expensive chemical process than making it from sugar.

Several pilot projects demonstrated the technical feasibility of making ethanol from cellulose. None had found a way to make it profitably. It looked, however, like a profitable business was on the horizon. How did that work out? 

The promise of ethanol from cellulose

In 2012, Chemtex International opened a commercial cellulosic ethanol plant in Crescentino, Italy. By 2016 it was operating daily and selling its ethanol all over Europe. Chemtex was a subsidiary of the Italian chemical giant Gruppo Mossi & Ghisolfi,

Mossi & Ghisolfi formed another subsidiary, Beta Renewables, to license its “second generation” technology, which it called Proesa™. GranBio, a Brazilian company, obtained a license. It opened a plant in São Miguel dos Campos in 2014. Another Brazilian company, Raizen, opened a combined first- and second-generation ethanol plant the same year. Neither plant operates continuously, and both operate at less than half capacity.

Chemtex received a grant from the US Environmental Protection Agency to grow switchgrass in North Carolina. Apparently, it never built a plant to make ethanol. I find no recent news about cellulosic ethanol in North Carolina.

Unfortunately, Mossi & Ghisolfi’s Cresecentino plant shut down in October 2017. The reasons had nothing to do with cellulosic ethanol technology. It went bankrupt from delays and cost overruns in starting to make resins for PET bottles in Corpus Christi, Texas. Hurricane Harvey, which struck in 2016, caused many of the problems.

The Beta Renewables subsidiary suffered its own problems. Its CEO, Guido Ghisolfi, committed suicide in 2015. It continued, however, to look for new places to license its technology around the world. Companies in India and Indonesia had begun negotiations. The bankruptcy judge gave it 60 days to reorganize. Its website has no content posted since the announcement of the bankruptcy.

So Beta Renewables offered one workable technology that exists. But no one but GranBio can legally use it.

Apart from the Proesa process, numerous companies all over the world have attempted to make ethanol from cellulose. Many ceased operation only a few years after opening. No American company has produced as much as 10 million gallons per year (MMgy). (The Crescentino plant produced 13 MMgy. Raizin’s manages 10 MMgy.)

Some remaining technological and economic problems with ethanol from cellulose

Corn stover harvest

Ethanol is made by fermenting glucose, a simple sugar. Cellulose is the major component of plant cell walls. It comprises very complex chains of sugar molecules. Breaking them into fermentable simple sugars requires complicated and costly chemical processes.

Switchgrass and other biomass is very heavy. Therefore, it is not economical to transport it more than about 50 miles. Corn stover and other agricultural wastes can also serve as ethanol feedstocks. But even if shipments don’t weigh as much, transportation costs remain an issue.

Scientists researching recycling of rare earth metals have used such wastes to extract glucose that is less expensive than commercially available refined glucose. But they don’t need as much as an ethanol processing facility would.

The cellulosic ethanol plants in Brazil use sugarcane trash, that is, the parts of sugarcane the sugar industry can’t use. That means they can only obtain it during the sugarcane harvest season. Therefore, they can only operate about 200-240 days per year. Three years after beginning operation, the two Brazilian companies have still not found the most efficient ways to use their equipment.

The high cost of obtaining biomass, added to the high cost of extracting fermentable sugars from it, makes ethanol from cellulose much more expensive than corn ethanol. Add unsolved problems with pre-processing and processing equipment and regulatory uncertainty, it’s no wonder cellulosic ethanol hasn’t lived up to its promise so far.

Some experts expect that it will become profitable within the next ten years. We’ll see.

Sources:

Beta Renewables in cellulosic ethanol crisis, as Grupo M&G parent files for restructuring/ Jim Lane, Biofuels Digest. October 30, 2017
BetaRenewables website.
Cornfields could play a role in recycling old electronics / Laura Millsaps, Phys.org, March 15,2018
Global cellulosic ethanol developments / Susanne Retka Schill, Ethanol Producer Magazine. March 14, 2016
Inside the cellulosic industry / Susanne Retka Schill and Ann Bailey / Ethanol Producer Magazine. July 26, 2017
Second-generation ethanol can be economically viable by 2025 / Elton Alisson, Agência FAPESP. October 18, 2017

Photo credits:
Switchgrass. Some rights reserved by eXtension Farm Energy.
Corn stover. Image courtesy of Idaho National Laboratory (INL) Bioenergy Program, via Flickr