Feedstock, Supply Chain, Energy Crops

Biomass feedstocks are a biological renewable material that can be converted to fuel or energy. Some examples of these that we saw are corn, sugar beets or woody plants.  Feedstocks need to be reliable in supply and economical. They are land intensive and must be harvested and collected requiring a lot of energy.  There are four major groups of feedstocks (European Biofuels Technology).

Agricultural Residue:  These are the left overs after the main product is harvested.  It can include corn silage, straw and animal manure.  This kind of feedstock is beneficial for biogas plants that are located near agricultural areas.   While in Munich, we were able to tour the Munich Zoo‘s anaerobic digester.  They use manure from the plant eating animals at the zoo mixed with hay in their three fermenters.  They are able to produce 240,000 kWh a year and use the heat from the engine for the Zoo’s heating system.  This biogas system keeps about 190 tons of CO2 from entering the atmosphere every year (Zenau).


Group photo in front of the three fermenters at the Munich zoo.

Biowaste: This comes from sources like municipal waste, food waste, sewage sludge or garden waste. using biowaste gives the advantage of not using energy to create a feedstock that doesn’t already exist.  This is very efficient if the waste can be used directly and not have to be processed greatly or separated.  These kind of biogas plants that use some waste have a greater range of where they can be located.

Forest Residues:  This feedstocks comes from the left overs after wood harvesting including twigs, branches or foliage.  Forest residue can also be harvested directly.   Smurfit Kappa, the largest of its kind of paper industry in Europe, uses the saw dust and wood chips from their woody biomass to supply half of their energy needs for the plant.


Smurfit Kappa’s wood chip piles


Smurfit Kappa’s wood deliveries waiting to be chipped

Energy crops:  These are crops grown specifically for the purpose of using them as biomass to create energy.  Over the course of the trip we saw quite a few energy crops.  These included a woody biomass plant in Sweden.  Skelleftea Kraft uses woody biomass as its main source of energy but also receives saw dust in order to make pellets which can be used as energy as well.

In Munich, Germany we visited an anaerobic digester that uses sugar beets as a feedstock.  ROPA is a sugar beet harvesting equipment company first off and secondly produces energy on site with the digester. This is considered an energy crop because the beets are harvested directly to produce biogas.

ROPA's anaerobic digester system

ROPA’s Anaerobic Digester of Sugar Beets

In Frankfurt, Germany we visited the Bauer farm that grows corn to be harvested for use in an onsite digester producing biogas for energy and operating as a combined heat and power plant.

Bauer farm storage

Bauer Farm’s piles of corn silage ready to be mixed with manure to go into their anaerobic digesters.

These crops must have maximum output per hectare in order to be economical and environmentally friendly. Management and farming practices must be monitored. Controversy surrounds feedstocks in areas where food supplies are limited.   In areas like Sweden where the forestry industry is large, energy crops are not as prevalent since woody biomass can be collected easier and at cheaper costs. The feedstock supply chain has major risks associated with it as crops are not always reliable and the capital costs are very high.   In the United States, the price of corn is too high to use it as an energy crop.  The most promising feedstock for the United States will be in residues and waste that are not tied to the food industry.

Bio-fuel feedstocks are connected to biomass feedstocks but go through a separate and sometimes additional process to  be created.  They can be categorized as first or second generation fuels based on their origins.   First generation biofuels comes from food crops like grain or sugar beets (Fischer).  This conversion from biomass to bio fuel is rooted in the biochemical reaction of biomass to ethanol using the sugars in the feedstocks.   As previously discussed, with the increasing fear over using crops for energy, 2nd generation biofuels are becoming more popular.  2nd generation biofuels are from nonfood biomass feedstocks like straw, forest residues or energy crops like miscanthus that have no tie to the food industry (Sims).   The main processes for 2nd generation bio fuel production comes from combustion or gasification of the biomass to convert it to syngas (Fischer).  Pictured below, ETC used the black liquor from Smurfit Kappa’s paper production to create snygas from gasification which can become DME through refining processes.   This is an example of a 2nd generation biofuel.


ETC Biomass Gasification Plant in Piteå, Sweden

1st generation bio fuels are limited to the use of arable land only, while 2nd generation can come from all types of land and climates.   However, there is great variability in 2nd generation bio fuel feedstock which could impact production and costs.  One step to increasing these bio fuels will be creating a sustainable and reliable 2nd generation feedstock.  Also without major government incentives or subsidies, the price of biofuels, especially 2nd generation are not yet competitive.   With advancements in technology and governmental support, bio fuel feedstocks could become more economic in the long run.


European Biofuels Tenchology Platform. (2012). Sustainable Feedstocks for Biofuels Production in Europe. Retrieved May 7, 2012 from http://www.biofuelstp.eu/resources.html

Fischer, G., Hiznsyik, E., Prieler, S., & van Velthuizen H. (2007). Assessment of biomass potentials for biofuel feedstock proudction in Europe: Methodology and results. Retrieved May 7, 2012 from http://www.refuel.eu/uploads/media/Refuel-D6-Jul2007-final6.pdf

Sims, Ralph , and Michael Taylor. “From 1st to 2nd generation bio fuel technologies .” International Energy Agency . N.p., n.d. Web. 12 June 2014. <http://www.iea.org/publications/freepublications/publication/2nd_Biofuel_Gen.pdf&gt;

Zenau, R. (Director). (2014, May 23). Tierpark Hellabrunn. Tour from Munchener Tierpark Hallabrunn AG, tierparkstrasse


4 responses to “Feedstock, Supply Chain, Energy Crops

  1. Do you think with policy changes in the U.S we would turn more towards feedstocks that don’tt impact the general food stock, and therefore could lead to the production of anaerobic digesters to reduce waste and increase renewable energy production

  2. Yes. I think that as we saw with the increase in ethanol from corn, the food prices increased quickly and dramitcally. If another feedstock is choosen as the main renewable energy were going to go with, the United States would have to go with one that would not affect the food supply anymore. Something like that can give renewable energies a bad name in the eyes of Americans who aren’t educated on the topic and only see prices increase. The most promising feedstock in the United States is waste either from food or agriculture.

  3. As we heard from the speakers, Sweden and Germany are providing government subsidies to promote stimulation in a specific sector of energy. Is there any reason why the government would reduce subsidies besides not having enough funds for other social projects? If so, could that be disastrous for anaerobic digesters that depend on the subsidized prices to pay off the capital costs of their equipment/sustain theirselves, and could that mean that, in the future, previously subsidized feedstock wouldn’t be able to compete with the price of natural gas, gasoline, coal?

    • The main purpose of a government subsidy is to create a viable market for something to grow. In the case of renewable energy, government subsidies are in place to make it easier and more attractive for companies to put in the capital cost and even research in most cases to begin production and implementation of things like anaerobic digesters. The subsidies are not intended to last forever. Once the market is there for renewable energies and the industries are established and growing, the subsidy could be removed. It is the idea that at this point the innovation allowed under the subsidy has made it less expensive to create and produce renewable energy. Also, the consumer market would be established hopefully to a point where it remains viable without government assistance. This being all hypothetical and in a perfect world. Realistically, governments can feel pressure to remove these kinds of subsidies if they are causing a real impact on a competing industry, like the coal industry which in Germany is large enough to sway the government. The biogas plants in Germany are suffering and dwindling right now due to the increase in prices. This will be disastrous to the biogas industry there in the upcoming years.

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