Is your head swimming with acronyms and blend ratios?
Who exactly is making drop-in fuels, and what does that mean?
In the world of alternative fuels and transport, there are two types of technologies that are highly controversial:
1. Specifically to biofuels, fuels made (exclusively) from feedstocks that are also used for food production.
2. In every alt transport sector, infrastructure-incompatible fuels or engine technologies.
While fuel or vehicle cost impact is a huge factor in adoption, much of the squabble over the US Renewable Fuel Standard, for example, has to do with how ethanol matches up with the existing vehicle fleet and fuel transport infrastructure.
The fact that Brazil solved a lot of those challenges, years ago, is one of the reasons why major petroleum producers like BP, Shell and Petrobras are diving into Brazilian ethanol while refiners in the US have been, by and large, tepid in their support.
Meanwhile, in the US producers have reached the distribution wall imposed by E10 blend limits; E15 blending is early-stage and controversial; for higher blends, there’s an acute shortage of pumps, and E85 prices aren’t tempting many customers.
But the controversy over infrastructure extends well beyond ethanol. Biodiesel producers have worked hard to move accepted blend ratios beyond B5 towards B20 and eventually B100. For compressed natural gas (CNG), there are only around 500 pumps in the country; for liquified natural gas (LNG), there are only around 40, and most of those in one state (California). Battery-electric vehicles struggle with recharge facility availabilities and charge-time.
Over to drop-ins
Which brings us to the drop-in fuels.
These are, by definition, infrastructure-compatible fuels — although, as we shall see, fuels form a spectrum and there really isn’t a simple “wall” dividing incompatible fuels and drop-ins.
Generally around the world, fuels are blended by refiners – who add anything from oxygenates to detergents — and for the foreseeable future, expect to live in a world of blends.
So, here’s a guide to the world of drop-ins and dropping in.
1. Drop-in intermediates for petroleum refineries.
These are feedstocks that can “drop into” existing refining capacity and can be used to make infrastructure-compatible fuels. These can include, for example, upgraded pyrolysis oils of the type that KiOR makes. For now, KiOR is upgrading at its own facility to demonstrate that it can make 100% drop-in, finished fuels — but they could, long-term, position themselves as a supplier of intermediates to conventional refiners.
These also can include renewable oils which can be “dropped into” a hydrotreating unit to make HEFA jet fuels, which are now certified for use in commercial aviation at 50/50 blends with conventional jet fuels.
2. Drop-in intermediates for biorefineries.
These are, for example, renewable sugars that can be dropped in to fermentation systems and used to make, for example, cellulosic sugars at an old corn ethanol plant; or, synthetic biology technologies of the LS9, Amyris or Solazyme type can use them to make a range of tailored drop-in fuels and chemicals including diesel and jet. Catalytic technologies of the Virent type can also convert them into renewable diesel or jet — as well as chemicals.
The renewable sugars can be made from a variety of non-food feedstocks — and Proterro is making them via synthetic biology directly from water, CO2 and nutrients.
Renewable sugars developers include Renmatix, Virdia, Sweetwater Energy, Comet Biorefining, Proterro, and Bluefire Renewables.
3. Drop-in gasoline, diesel and jet fuels.
Companies like Diamond Green Diesel, Dynamic Fuels and Neste Oil have built or are constructing, in biofuels terms, large-scale refineries to convert biobased oils to diesel fuel via hydrotreating. These can be blended by refiners or used as a 100% drop-in replacement. And, these providers can also produce renewable jet fuel at their plants.
In addition, there are the above-mentioned diesel and jet fuels made by the likes of LS9, Amyris, Virent from renewable sugars. The jet fuels are generally of the HFA spec, that can be blended in 50/50 ratios with conventional jet fuels.
Coming along in the development pipeline, there is the technology developed by Chevron Lummus and ARA – that makes a 100% drop-in jet fuel from renewable feedstocks. There has also been research in making jet fuel from biobased terpenes — and these could have enough fuel density to be used as a 100% drop-in replacement for JP-10 fuels, which are used for selected high-performance technologies like guided missiles.
Companies like Butamax, Gevo, Cobalt and Green Biologics are developing biobased isobutanol(Butamax, Gevo) and n-butanol (Green Biologics, Cobalt).
Isobutanol is case in point when we talk about “drop-in” being a spectrum rather than a spec. It is fully compatible with fuel infrastructure – e,g, tanks and pipelines and vehicle tanks and fuel lines. In terms of engine performance, it blends in at up to 60 percent with no loss in performance. However, EPA rules on emissions limit biobutanol right now to 16 percent blends (as a maximum – DuPont earned a waiver some time ago at that level) or 12.5 percent (generally). There is hope that biobutanol waivers could be issued by EPA for up to 24 percent blends in the future — but that is a ways off.
Of course, for those comparing butanol to ethanol, it’s also worth noting that a gallon of isobutanol has the energy density of 1.3 gallons of ethanol. So, you can travel roughly twice as far on the renewable molecules in a 16 percent biobutanol blend than the molecules in a 10 percent ethanol blend.
A lot of people regard biodiesel as a drop-in fuel — and its true, there are vehicles out there running on B100 today. Generally, though, B20 is the maximum blend for which carmakers will not void a warranty, today, and a lot of vehicle models are still only approved for B5. That’s changing – slowly.
At the same time, biodiesel has come infrastructure incompatibility when it comes to pipelines — it can’t be mixed, not one drop, with jet fuel.
Now, there are E100 cars in Brazil, and there are ethanol pipelines there, too. So, for that reason, sometimes you hear about ethanol being described as a drop-in fuel. Which is to say, it drops-in to some cars and infrastructure, but far from all.
In the US, ethanol is not compatible with pipelines, and requires its own special tanks and equipment because it corrodes conventional fuel storage.
With vehicles, it depends. Cars made since 1995 tolerate E10 ethanol blends. Cars made since 2001 tolerate E15 blends. Plus, there are more than 10 million “flex-fuel” vehicles that can drive on blends up to E85. Of course, there’s the problem with pumps — very few E15 pumps out there, and only about 3,000 E85 stations compared to well over 100,000 conventional fuel outlets.
Who’s Making What?
In the chart below, we look at the 50 Hottest Companies in Bioenergy to see exactly who is making what, and what progress they have made towards commercial-scale.
6 companies are excluded because they made the Hot 50 as feedstock developers (e,g, seeds and crops) or as downstream strategic partners. Of the remaining 44, eight make renewable sugars, yeasts or enzymes — these do drop-in at biorefineries, but are outside of the “fuels” category.
Of the remaining 36, 18 make ethanol, 3 make biobutanol, 3 make biodiesel, and 13 make high-blend or 100% drop-in replacements. (Doesn’t add up to 36? LS9 makes bnth biodiesel and drop-in surfactant alcohols, plus diesel and jet fuel).
Of the 13, eight have completed scale-up demonstrations of the technology and are developing first commercial projects, one is constructing a first commercial facility, two have completed small commercial plants and two are operating (Neste and Dynamic Fuels) full-scale commercial biorefineries.
That’s a lot of progress. Six years ago, none of the 13 were operating at anything larger than pilot-scale – at least four were still at lab-scale.
Interest in companies with drop-in capabilities remains intense. Of the 13 companies in the Hot 50, eight of them are found in the top 16, and they currently hold the top two positions (Solazyme and KiOR).
The Digest’s 3-Minute Drop-In Guide
More background on the story from the Digest
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