Ed Rosenthal did an AMA (ask me anything) on reddit today, what fun to have a word the HT Ganja Guru! I had met him back in the Van Nuys Hemp office in 1994 when he had come to visit Jack. It was an interesting time to be a ‘fly on the wall’.
So, on the AMA I posed this question to him: Where do you stand on hemp as a biofuel. Your disagreement with Jack Herer was well-known as you had cited corn, cattails and algae as better sources. Do you still
maintain that these are more viable than hemp today?
All plant matter contains about the same amount of carbon. Whether were talking about dried leaves, or wood, pound for pound they have about the same amount of calories. Since seasonal leaf drop is ubiquitous throughout the eastern portion of the United States, and those leaves are collected and taken to the dump, you would think that the first place to look for renewable, fuel would be with a product that is already harvested but isn’t used. This and scrap plant matter have not yet been used for fuel.As far as using hemp for this, all parts of the plant are too valuable to use for fuel. There would be a terrific economic cost to using it. When planting more of the country with hemp, corn, or any other plant for bio-fuel the cost of production goes up when marginal land is used, as the same inputs are applied but the yield is diminished. I do think that at some point recyclable carbon fuels will be used, but I don’t think it will be from annual plants. Using some trees would produce more net calories than hemp, especially when the cost of annually planting and harvesting hemp is taken into account.
My Response to Ed:
Hi Ed! Glad to hear from you – while I’m not sure you’ll remember meeting me ‘back in the day’ when I was working on Jack’s book in an editorial capacity. I’ve always appreciated your work, notably as an expert witness.
I appreciate your thoughtful answer, the idea of collecting leaves makes for a great case here. Dried biomass has a heating value of 5000-8000 Btu/lb, with virtually no ash or sulfur produced during combustion. However, you still miss the mark on the one thing that makes hemp a viable resource as a crop grown for energy: ENTROPY, or lack thereof. It takes much more energy to grow the crops you mentioned in your book challenging the claim. I mean you no disrespect, but you’re no scientist and completely overlook the math. Let me help you with this – Energy efficiency is the ratio between useful energy output and input energy, and can be expressed simply as follows:
µ = Eo / Ei
µ = energy efficiency
Eo = useful energy output
Ei = energy input
While you are correct in asserting that amount of carbon expressed is close to equal in all plants, the fact is that it takes far less energy to grow hemp than it does corn, cattails, algae, [some] trees and so on. If we are to take into account the cost of harvesting hemp, then we must take this into account for all matter in question. Corn, not only requires a huge amount of water, but it also needs fertilizer and pesticides to grow massive amounts sans a bio diverse ecosystem; algae is similar in that it take a large amount of standing water as do cattails. The annual yield of each crop will need to be considered for the equation as a perennial model will simply not be viable in an energy formula. Hemp can yield 10 tons per acre in four months and contains 80% cellulose; wood produces 60% cellulose. Hemp is drought resistant making it an ideal crop in the dry western regions of the country.
In regards to hemp and the notion that parts of the plant are too valuable to use for fuel is a matter of perception. I’m certain you know ditch weed grows crazy fast in its annual cycle with little help from anyone. When farmers can grow hemp as a biomass source they will profit as energy farmers.
Note: heavy citations from Energy Farming by Lynn Osburn here: https://ratical.org/renewables/eFarming.html