Biofuels’ 10 scariest challenges: Part 2 of 2

4. Affordable Aggregation of Feedstock

In our “3 reasons why waste is king of renewable fuels” we wrote:

1. The feedstocks are available at fixed, affordable prices – sometimes free, sometimes even transitionally available with a negative-cost tipping fee. And available in fixed, long-term supply contracts.

2. The odious sources are generally already aggregated, for health or noxiousness reasons.

3. They are less subject to considerations such as indirect land-use change that have plagued energy crops, and evoke few protects, if any, from environmental extremists.

Of course, the opposite is true of some other feedstocks — and of all the problems that beset biomass, there’s nothing more difficult to address than aggregation.

The problem? The impossibly high cost of sourcing sufficient biomass within, say, a 50-mile radius. After 50 miles or so – a little less, if small trucks are used, a little more if barges or rail are used — the economics of transporting raw biomass become impossible. Too much oxygen, too much water — the weight is a killer.

That’s one of the primary reasons why refineries in the bio-space rarely exceed 25 million gallons for projects based on agricultural residues, 50 million gallons for woody biomass, and 250 million gallons for waste or crop-based oils.

An interesting work-around that has gained currency in recent years has been the production of biofuels in what transport mavens call the hub-and-spoke system. In these scenarios, smaller biomass projects manufacture refinery intermediates rather than finished fuels. They are then shipped in a highly densified form to massive refineries where they are converted to finished fuels and chemicals.

We looked at the phenomenon in “Super-cali-thali-terpa-butyl-peta what? The hockey-stickin’, flash-mobbin’ growth in biobased intermediates.”

The hottest category is renewable sugars, which has attracted companies like Virdia, Blue Sugars, Proterro, Renmatix and Sweetwater Energy. Their challenge? Produce low-cost, high-performance renewable sugars that can be sold to synthetic biology companies like LS9, Virent, or Gevo, who convert sugars into an array of useful end products ranging from surfactant alcohols, base chemicals like isobutanol, or diesel, jet or alcohol fuels.

Intermediates have become a fashionable strategy for a couple of reasons. For one, they are getting better at what they do, and more of them are popping up. Take for instance, Waste Management, which is now getting deeply involved with Renmatix and renewable sugars. That way, they don’t really have to worry as much about, for example, picking processing technology winners.

Why hasn’t this been done all along the way? What are some of the down sides of intermediates? A big issue is stability.

Biofuels are a little like wine and champagne – their chemistry can continue to evolve, and in 6 months after sitting in a tank, what you may not have is the same in-spec material you started with. (That’s why, for example, champagne pops when you pull out the cork – it has been fermenting in the bottle and that releases CO2, which is what causes the pressure build-up).

Some molecules attract water, some oxidize. With renewable sugars, there are fears that bacteria will have a field day and gobble up the product if you try and transport renewable sugars via a pipeline – and who knows what you’ll end up with at the other end.

In today’s Digest, follow the page links below for each Scary Challenge – and potential solutions.