Biological or Thermochemical – Place Your Bets!

Which is the best way to convert biomass to transport fuels? In the red corner, the Ninja – the micro-organism, be it yeast, bacteria or algae. It is stealthy and very skilled, clever and adaptable. But ultimately fragile and temperamental. In the blue corner, the Troll – the reactor, using brute force (also known as high pressure and temperature) to bludgeon the feedstocks into the desired products. It is immensely powerful. But ultimately, heavy (ie expensive) and unwieldy.

You could think of it as David vs Goliath. Or, to rebalance the odds and avoid any perception that I am calling the fight: If you were obsessed a few years back with the Game of Thrones series (yes, me too), you could think of it as the famous fight between Oberyn Martell and the Mountain. Except that this time (spoiler alert!), the only skulls likely to be crushed – figuratively speaking, hopefully! – are those of unwary investors trying to pick a technology winner.

What I find most amazing here, is that this big dispute between the two philosophies of bio-manufacturing has been around since the dawn of biofuels, and shows no sign of abating. After all, even the two classical first-generation incumbents are divided by it. Ethanol fermentation is a simple and straightforward biological process. Conversely, trans-esterification of lipids into FAME is a simple and straightforward (and very mild) thermochemical process. Many over the years have purported to call the race. In the mid-00’s, the team I was part of made a big commitment to biology, betting heavily on the ability of super-enzymes and super-bugs to convert the toughest materials into the highest value fuel products. Around the same time, others made similarly bold bets on thermochemical pathways; perhaps the most obvious example was Neste’s commitment to hydrotreatment.

But the two schools of biofuels production are best compared when put in direct competition using the same raw material. Today, the holy grail of processing ligno-cellulosic biomass is subject to the same fundamental choice as ever. Do you a) capitalise on the work already done by Nature when She created those carbohydrates in the form of cellulose and hemi-cellulose, and carefully recover them / break them down into fermentable sugars? Once you have those sugars, and assuming you haven’t broken the bank, the hardest job is done; micro-organisms can be cajoled or coerced into converting them into a whole array of valuable molecules, from your simplest fuels (ie ethanol) to your most sophisticated health and cosmetics applications.

Or do you b) subject the biomass to high pressure and temperature, blitzing its molecular structures in order to recover the carbon in a form which can be reshaped into fuels? Best-known pathways vary from making syngas then Fischer-Tropsch diesel, to making pyrolysis oil, which is liquid energy – that’s about the nicest thing one can say about it – but needs a lot more refining before it can go in a car. Not to mention more novel variations, all on the theme of subjecting ligno-cellulose to brute force and ending up with liquid fuels.

OR is the answer c) to mix and match the two fundamental philosophies, get biology to do part of the job and chemistry to do the rest? A simple example of that would be the heterotrophic algal pathway, where algae convert sugar into oil before said oil is hydrotreated into high quality fuels. Once you start mixing across the various steps of your manufacturing process, the permutations are almost infinite. No wonder therefore that biofuels start-ups are still springing eternal, inventing increasingly complex ways to try and get the best outcome. Add to that the fact that “best outcome” is itself a nebulous concept (different pathways will result in different product slates with different financial shapes, different scalability, different WtW carbon balances and wider sustainability impacts, and responding differently to various regulatory frameworks), and here comes the skull-splitting headache for investors eager to make a material commitment to the sector, but hopelessly confused by the myriad of possibilities dangled in front of them.

Thankfully there is a saving grace here. There is probably a good reason why the biofuels world cannot decide which is best, biological or thermochemical routes. It’s probably because both have a place, and there isn’t one clear winner because there isn’t one problem to solve, but many. Different feedstocks, giving different products for different transport modes into markets driven by different regulations, was never going to lend itself to one-size-fits-all. Understanding not just the risks, capex and opex of each technology, but the complex system of regulatory-driven supply and demand and alternatives in which your product will play, is crucial to formulating a robust business plan and creating a successful advanced biofuels project – bearing in mind said project doesn’t need to solve the global climate crisis by itself, it just needs to be the right solution to a problem commensurate with its size. With that, there will continue to be a place in the biofuels constellation for many stars, big or small.

Broadmanor Consulting advises businesses wishing to invest in the biofuels sector. Investors can benefit from our understanding of the end-to-end biofuels value chain, from technology choices to sustainability considerations to product monetization across various regulated markets.

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