From Fryer to Fuel

I have created fuel from fryer oil!  My batch filtering/storage system is fully functional.  Last night I processed around 30 gallons into usable fuel.  After several months of slow progress, I have a system in place that I'm quite happy with.

The process of collecting and filtering the oil can best be described as a an industrial art.  Handling this non-polar substance requires a fair bit of patients and a mountain of paper towels.  The goal of any waste veggie oil (WVO) processing system is to make it as closed as possible.  The more containers and transfers one must undertake, the more spills and splatters one must contend with. Cardboard has become my best friend, creating an absorbent foundation for the oil that seeks freedom from the fuel tank.

My filtering setup was inspired by many other systems used by many other home wvo processors. The idea is simple, start with used fryer oil and end with fuel oil.  Generically speaking, the processing sequence is as follows:

1. Settling
2. Progressive filtering
3. Final filtering/water removal

The design of the system allows for me to insert oil in the start (heated settling tank) and run it through from there to the storage through a closed pipe system.  Linking the components reduces the chances of spilling oil.  Leaks exist, but losses are negligible and are caught up by containers and cardboard.

System Diagram

The collection stage, not pictured here, helps to settle the oil.  I collect and hold it in 5 gal buckets for at least a week if not longer. I then pour it into a cubie (fryer oil is sold in these 5 gal plastic containers), letting it settle again for at least a week.

Settling the oil reduces the filtering overhead and helps to remove some of the entrained water. Despite the generalization that water and oil don't mix, fryer oil has varying degrees of water both trapped in both the food particles and suspended/emulsified in varying quantities.  From a thick substance unaffectionately referred to as "mayonnaise" (the culinary version being a water/oil emulsion) to molecules dissolved throughout the oil, water is one of the more difficult substances to remove.  Extended settling and decanting goes a long way to eliminating the bulk of the water. 

From settling, I transfer the oil into the first stage of my system.  The previous post How reused fryer oil builds a house, shows this stage.  The key here is that the heated oil in the top tank flows out through a raised drain pipe, leaving behind the bottom 3 inches of oil which contains the heaver, water laden sediment.  That layer is drained off from time to time and sent to the oil recycler. The oil passes through a 200micron mesh sock filter.  For comparison, a human hair is roughly 90 microns (fun fact: merino wool is down around 25 microns).

The oil is then pumped up into the CF (centrifuge) feed tank. Gravity fed through an inline heater The oil feeds into the centrifuge and then out to the storage tanks.  I purchased a bowl centrifuge from WVO Designs.  The inline heater was built from scratch using a 1100watt hot water heater element.  It heats the oil between 140 and 170 deg F.

Running through the centrifuge

The tank in the background is the CF Feed Tank.  It's filled through the exposed barb on the left.  The inline heater element is protected by the purple cup (exposed terminals) and you can see the path thie oil takes as it flows from the CF tank through the black hose, up through the inline heater and then over to the top of the centrifuge.  Spinning at 3000 rpm, the centrifuge forces the heaver particles to the bowl sides while the clean oil flows up and over, draining into the storage tank (left foreground). I'm working on dialing in the flow rate. Notice the three feed holes on top of the centrifuge.  From the open holes vapor vapor wafts out as the hot oil spatters into the spinning bowl allowing the hot dissolved water to break free.

Stages of oil

From left to right, the Raw oil collected from the fryer, the oil after settling/200 micron filtering, and finally, the fuel! At 14 mpg, this half pint on the right represents just under one mile of fuel.

Sludge

Left behind in the bowl is the darker, heaver oil and free water.  Plastered against the bowl sides is a think, black sludge of the larger, solid particles removed from the oil.

How reused fryer oil builds a house

Today I passed a small milestone in my house building project.  I created the first stage of my fryer oil filtering system. How, you may ask, does this relate to building a house?  The answer: transportation cost.  I shall explain.

The black container on top has a drain pipe roughly 3 inches high.  The oil settles, leaving the heaver "french fry" particles below the drain pipe.  The orange strap heater brings the oil to around 70F or 80F.  When ready, the vertical stick, attached to the plug, is pulled and the oil drains into the plastic barrel.  On its way it passes through a 200micron mesh "sock" filter.  The next step in the chain will be centrifugal filtering! 

The transport of goods for building are often transparent.  I strive to attain goods as locally as possible though some "local" goods may have traveled over great distances. Some materials can be created locally and I'll strive to use those first. To that end, I bought a diesel pickup intended to transport that which I can. Bricks, for example, are nearly always a regional material.  Picking them up myself cuts out a transportation link.  Diesel engines can run on waste vegetable oil (WVO).  Using such fuel helps to build my house more efficiently (I hope!)

To the savvy (and to those who are always trying to poke holes in sustainable concepts for the sake of argument), any discussion of energy sources exposes some of the embedded costs of handling and processing of fuel.  Even though I get the oil for "free," the actual cost of the fuel is far from free.  As of this writing, I've collected around 100gal of used oil, and spent around $2200 making the cost of the raw material roughly $20/gal.  That's quite a bit more than the current price of petrol diesel at $3.60/gal.  Without going into a long rant over the geopolitical economics of petroleum fuel, the price at the pump is considered underpriced as a result of cost externalizations.  Even factoring in an extreme measure of cost externalization, the price of petrol diesel probably doesn't approach $20/gal. Over time I can and will bring that price down, though the question becomes "by how much?" and is it sustainable?

Any discussion of fuel must necessarily encompass the production methods.  The production methods of veggie oil, while petroleum dependent, are no more so dependent than the production petroleum itself. The veggie outputs are not only more attractive from the standpoint of use (lower emissions pollutants, carbon cycle, etc), but the overall production impact is less when considering the byproducts of veggie oil production are far less toxic than that of petroleum.  All in all, using such fuel is a step in the sustainable direction by reducing externalization and the carbon cycle.  Bio fuels aren't perfect (maybe not even truly sustainable) though they are far more sustainable than petroleum fuels. Efficiency is the game even if sustainable is still too difficult to declare.

And that brings me to today where I processed roughly 10 gallons of oil through a 200 micron sock filter.  It didn't clog, and it filtered quickly.  Anyone who's tried to filter used veggie oil knows that it can go very wrong very fast and create a situation that is nigh on impossible to clean up.  Once operational, I can shift 90% (or better) of my fuel use to a more efficient fuel.  A fuel that reduces cost externalization.  A fuel that reduces pollutants.

And taken to the next level: I will have reduced the overall cost footprint of my house just a little bit more.

Is it Dirt or Soil or Earth?

I have a big pile of dirt in my yard.  It's for my Compressed Earth Block (CEB) chicken house.  Only, CEBs are made of "earth."  That begs the question, do I have the right kind of earth?  As it turns out, I do.  But what is meant by earth, anyhow?

Dirt gets such a bad rap.  When you look at the components that makes up dirt, you can easily see that the clay bit is what *ahem* soils the good name of dirt!  The sand and organic fractions don't get nearly the negative press that clay does, especially when it comes to mud!  Still, dirt is highly variable, and those three components, sand, clay, and organic matter, are the basic components of dirt.  A soil engineer could expound ad nauseam on the myriad aggregates and clays and their properties in various soils.  For the CEB enthusiast, it boils down to a few simple rules.  70ish% sand, 30ish% clay and as little organic matter as can be achieved.  So while there are many many many types of earth, when it comes down to it, CEBs require a rather narrow definition of earth.

My soil, as I pointed out, fits the bill for CEBs.  As a matter of fact, it's nearly ideal.  This soil was excavated for a building foundation so it's subsoil rather than topsoil. All subsoils have differing ratios of base components, so I did the basic "jar test" to get a quick assessment of the fractions.

left: top soil, right: subsoil

For comparison, the jar on the left is a sample of top soil from a local garden center.  The organic fraction, in contrast to my soil, is much higher. It's great for top soil, bad for CEBs.  It's worth noting that adobe requires a fair bit of organic matter, as does wall renders (a fancy way of saying plaster). Given the nature of my project, and that I'm going to be stabilizing with lime, my soil will not need any further adjustments. Below is a filtered look to highlight the fractions.  The sand/gravel layer is nearly all fine sand.  I'm not sure about the relative sharpness of the sand yet.  Sharper is better. As a side note, my CEB soil sample settled clear enough that you can't quite tell that there is still water in that jar.

highlighted layers

Of course, when making CEBs for human dwellings, there are several more aspects of soil engineering to address.  To wit, clay plasticity, silt content, sand type (sharp or round) and aggregate size, to name a few.  As I get more into the project, I'll address these metrics little by little.