Make haste with waste

In yesterday’s Digest, we asked “How much grease is out there, and at what price?” And the data is thin. As we reported, even the awe-inspiring Billion Ton series of reports from the US Department of Energy stays away entirely from the topic of waste fats, oils and greases.

Courtesy of the billion-ton study, we do know quite a bit about cellulosic feedstocks. Most importantly, we have some hard data regarding agricultural residues.

Why are residues so important?

As we pointed out, when you compare them to homogenized, uniform, high-yield, purpose-grown energy crops. residues may be queer, but they are here. Not only available, but reliable, you can count on the fact that they will not so easily slip into the food stream. And, affordable — today, that is, and especially compared to traditional agricultural feedstocks that supply the food, feed and fiber markets.

Perhaps most importantly, they are sustainable. As residues, they do not require land use change to be tapped as a feedstock, reducing the carbon footprint in the journey towards low-carbon fuels. Nor do they induce indirect land use change, so far as common sense would tell us.

The hard data on ag residues

The DOE Billion Ton Update tells us that, at $60 per ton in constant 2011 dollars, there are 160 million dry tons of corn stover and agricultural process residues & wastes available in the US. At $80 per ton, there is 105 million dry tons of urban wood waste, mill residues and “primary forest residues” available to the market.

So, let’s consider 80 percent of that to be tappable in a reliable sense with affordable logistics — which would leave us with a market of 210 million dry tons of biomass available to the market, today, at a blended price of $67 per ton. That’s 3.4 cents per pound in feedstock cost.

A conversion technology that can produce 50 gallons per ton in the diesel and jet fuel range — that’s Fulcrum Bioenergy’s publicly-shared yield — well, that gives us 10.5 billion gallons of fuel, from that resource.

MSW as a feedstock

How much?

According to the EPA, in 2012, Americans generated about 251 million tons of trash and recycled and composted almost 87 million tons of this material, equivalent to a 34.5 percent recycling rate. On average, Americans recycled and composted 1.51 pounds out of our individual waste generation rate of 4.38 pounds per person per day.

How much of this is biogenic material? Here’s EPA’s estimate, 61.7 percent, or 154 million tons. There’s a water and ash content in this material, so it is generally processed into RDF, which is a Refuse-derived fluff.

Waste oils and greases as a feedstock

How much is there? WaterWorld reports:

Over 4 billion gallons of waste grease per year is generated in the United States, presenting costly challenges to wastewater treatment systems. (That equates to around 28 million tons). Local governments spend over $25 billion annually maintaining sewer systems, necessitating more effective strategies to contain the financial and environmental impacts caused by sanitary sewer overflows (SSO) and combined sewer overflows (CSO). In addition, many States are placing stricter requirements on industries to resolve issues with waste fats, oils and greases (FOG) before wastewater enters the sewer system, adding logistical and technological challenges to those faced by waste generators.

Waste fats

Mark Jekanowski of Informa Economics writes:

Livestock slaughter by-products, restaurant grease, and scraps from grocery stores and butcher shops comprise the three primary raw material streams processed by renderers. The total volume of these raw materials processed is es mated at 48.32 billion pounds in 2010, about 91 percent of which consists of slaughter by-products, ve percent is restaurant grease, and four percent is waste from grocery stores and butcher shops. 

Putting it all together

How much tappable waste is there?

Let’s consider that 80 percent of what’s out there can be affordably recovered. We’ll use 50 gallons per ton for cellulosic feedstocks as a target yield, and 85% of waste fats. By that count, there’s:

Agricultural residue
160 million dry tons
128 MT recoverable
6.4B gallons – fuels

Forest residue
105 million dry tons
84 MT recoverable
4.2B gallons – fuels

Waste greases
28 million tons
0.7 MT recoverable
35M gallons – fuels

Waste fats
24 million tons
19 MT recoverable
4.3B gallons – fuels

MSW
154 million tons
123 MT recoverable
6.1B gallons – fuels

TOTAL
471 million tons
21B gallons – fuels

The Digest’s Take

The numbers tell a story of a tappable resource that can provide a sustainable, affordable, reliable, available supply chain capable of producing some 21 billion gallons of diesel/jet fuel range molecules, based on recovering 80 percent of what’s demonstrably out there, and using the DOE’s price figures for agricultural and forest residues. MSW is available at negative cost, and there is an existing and affordable market in renewable fuels for waste fats and greases. For yields we have used those from technologies demonstrated over 1,000 operating hours.

Another point worth noting. Diesel and jet fuel generally generate between 1.5 and 1.7 RINs per gallon, because of higher energy density than the baseline, which is ethanol. The US target is 36 billion ethanol-equivalent gallons, or RINs.

So, the numbers here suggest that there’s a 34 billion set of RINs out there — to add to the 18 billion generated today. Given that a small amount of waste fats and greases are being already used for biodiesel and renewable diesel production, consider that there’s something like 52 billion RINs out there in US renewable fuels, from these sources.

And, we haven’t considered as much as another billion RINs available from conversion of biogas into renewable fuels, from dairy and other animals wastes and manures.