Energy Balance

I have been curious about the energy balance of our biodiesel operation. For each unit of energy we put in, how many are we getting back?

I once posed this question to the biofuels list, and the answer that came back was to “try Homer.”

I did that today. It is an amazing tool. It’s a Windows application that has been published by the National Renewable Energy Lab (NREL). It allows you to model energy usage across a huge array of platforms . It is packed with information. It automatically graphs efficiency, allows you to modify inputs, and is an amazing tool. Very cool. Check out
Homer.

I wanted to explore the impact of moving our refinery to a biodiesel powered generator.
My start point is that biodiesel made from virgin soy has an energy balance of 3:1. For every BTU of energy that goes into its production, three come out.

Into that number goes the growing, harvesting and pressing of the soy beans, including all the petrochemicals, pesticides etc. along the way. After they have put the precious oil onto petroleum powered trucks and brought it to the restaurants of North Carolina, and after the oil has been used to cook fries, we come in.

I should say before I begin that I am sitting at my brother Glen’s dining room table, looking out at a frigid Georgian Bay on Ontario’s Bruce Peninsula. Before leaving on this trip I took a bet with Zafer and Arlo as to whether or not Uncle Glen had seen his first daffodil of the season. When I arrived the snow drifts dwarfed my rented Echo.

This is an unbelievably scenic place, although somewhat inhospitable to human habitation. I have to say that by coming here I have placed my Key West suntan at great risk.

Glen preceded me into the renewable energy space. Much of my thinking, my library, and my investments in renewables have been as the result of Glen. And he does not suffer from math anxiety. In fact, he seldom bothers with calculators. Together we worked on the energy balance of the fuel which comes out of Piedmont Biofuels, and here is our assessment:

We travel about forty five miles to get our used cooking oil.

Let’s say my 1992 Dodge pickup gets about 15 miles to the gallon. That’s three gallons of B100 each way=6 gallons for pickup and delivery.

What we pick up varies. Let’s say we pick up fifty gallons of veggie each time, and let’s say we make one run per week.

When we make biodiesel we typically use between fifteen and twenty percent methanol to get a good reaction. Let’s say twenty percent.

And we use electricity in our process. I’m guessing about two hundred and fifty kilowatt hours per month.

I’m going to skip the propane that we use, since it has virtually been replaced by solar thermal, and the weather is changing in North Carolina. Tami tells me the boys were out picking flowers today. Hyacinths and daffodils and crocuses. From what I can tell tonight, Glen will not see a flower for months. He’s on the porch right now, firing up his propane grill to prepare a piece of fish which came out of the bay across the street. It’s nuts. It’s about zero degrees Celsius out there. That’s thirty two degrees Fahrenheit.

Glen says, “You know it’s time to start the barbeque when its no longer cold enough to freeze the bay.”

I wrap another blanket over my shoulders, curse his “wet” firewood supply and thank my lucky stars that I am not trying to compute energy balance on biodeisel in this forsaken place.

He’s excited about grilling outdoors tonight. “You know, ” he says excitedly, “I couldn’t have done this last week. ”

I’m trying to work on the blog. “How many BTUs per kilowatt hour?” I ask.

“3413,” he says, “I Couldn’t have found the grill under the snow last week.”

He works on turning on his outdoor speakers. “Listening to the Dixie Chicks outside is a sign of spring,” he proclaims.

I’m trying to find the energy density of methanol on the net.

Glen comes in with a bottle of olive oil that he has had on the porch. Holds it up to the light and says, “Check it outóno problem with flow.” The bottle is starting to accumulate frost. We have spent the afternoon discussing the inferior cold flow properties of waste vegetable oil.

I realize there are many folks out there, like Lorance from Boulder Biodiesel who has little sympathy for my desire for warmth. I think he’s originally from Mexico, and currently lives in Colorado, in the snow and the blowing wind. I have no idea if he has harvested daffodils yet, but if he has not, it’s time for him, and everyone else who has yet to see a daffodil to start moving south.

Back to energy balance.

Here are what Girl Mark would refer to as the “nerdy energy facts”: 128300 BTUs per gallon of biodiesel. 3413 BTUs per kilowatt hour of electricity. 56800 BTUs per gallon of methanol.

Since I am not an energy nerd, (and on Glen’s advice), I’m going to do this whole thing in gallons instead of BTUs.

We require 24 gallons of biodiesel equivalents to procure our incoming feedstock. And we use 6.65 gallons of biodiesel equivalents in electricity. And another 17.7 gallons of biodiesel equivalent in our methanol. That’s 48.35 gallons per month. This is what we require to make 200 gallons of biodiesel.

Divide one by the other and you get an energy balance ratio of 4.13. For every BTU we put into making fuel we take 4.13 BTUs out.

That’s a disappointing model. If virgin product is 3:1, we are not markedly better.

But I have been free and easy with the assumptions. If we sell a vehicle at Carmax when we pickup the veggie, where do we charge the energy? Sometimes we do the grease run when we are in town anyway. If we used Tami’s Jetta to pickup grease, our energy balance would be much improved. But if we did that, I would be single, and how would we calculate the energy balance in that?