Energy maize

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Corn ( Zea mays )

As energy maize is maize referred that for energy production in biogas plants is used. Since maize, as a C4 plant, has a low water requirement and only makes moderate demands on the soil, it is a widespread crop in Germany with high yields of dry matter per unit area. The generation of biogas is promoted by the Renewable Energy Sources Act (EEG). Energy maize cultivation was expanded, particularly after the introduction of the renewable energy bonus with the EEG amendment in 2004.

In terms of cultivation and variety, energy maize does not initially differ from other silage maize , which is primarily used as fodder. The term was coined to differentiate between the use for feed or food production on the one hand and for energy production on the other hand. Increasingly, however, the cultivation and the varieties used also differ from conventional forage maize .

In Germany, the share of energy maize in total maize cultivation was 33% in each case in 2012 and 2013.

Differentiation between energy and feed maize

Comparison of biogas raw materials
material Biogas yield
in m 3 per ton of
fresh mass 		Methane
content
Corn silage 202 52%
Grass silage 172 54%
Rye GPS 163 52%
Pressed sugar beet
pulp
ensiled		 125 52%
Fodder beet 111 51%
Biowaste 100 61%
Chicken litter 80 60%
Pig manure 60 60%
Cattle manure 45 60%
Grain Meat 40 61%
Pig manure 28 65%
Cattle manure 25th 60%

In 2012, around 2.7 million hectares of maize was grown in Germany. This silage maize was predominantly with around 2.15 million hectares. The above-ground parts of the plant are chopped, ensiled and used as animal feed ( maize silage ) in cattle farming or as a biogas substrate. The distinction is made primarily on the basis of the use itself. However, there may also be differences in cultivation and choice of variety. In addition, grain maize makes up around a fifth of the German maize cultivation area (2012: 0.529 million ha). In the form of Corn-Cob-Mix (CCM) or as grain, it is only used to a limited extent in biogas plants.

use

Conventional silage maize is breedingly optimized for use as feed and meets requirements such as high yields of dry matter per unit area, nutrients that are easily accessible in the cattle rumen and good ensiling to ensure long-term storage and thus year-round availability. The high yields per hectare and the existing and proven harvesting technology, as well as the good preservability ( ensiling ) make maize the main substrate in biogas plants. In principle, silage maize is always suitable for use in biogas plants. If the decision about the use of the crop is already made during cultivation, the energy maize production can potentially be optimized by selecting the variety.

Cultivation and harvest

Young corn plants
Silage production

The requirements for silage maize for cattle farming and for biogas production differ slightly. The parameters adopted from fodder maize cultivation are modified in some points for energy maize cultivation in order to increase the methane yield per unit area. The effect of these measures is partly controversial:

  • A slightly higher seed rate reduces erosion, but should also be able to increase the yield per hectare. The increased nutrient withdrawal should be compensated by increased fertilization .
  • An earlier harvest with a lower degree of lignification (lower crude fiber content) can increase the digestibility of the maize silage. Silage maize is harvested with a dry matter content (DM content) of around 32 to 33% , if possible , in order to ensure that it can be ensiled well and to prevent loss of substance. If a significantly higher TS content is associated with more lignification of the plant, this reduces the degradability in the biogas plant. Seed producers therefore sometimes recommend harvesting with a dry matter content that is 2 to 3% lower. However, other bodies do not consider this to be necessary. During ensiling due to the higher water content in the crop, organically contaminated seepage juices that may occur are ecologically problematic. B. be fermented in the biogas plant.
  • Maize varieties with higher ripeness are not suitable for cultivation for the production of feed silage under the climatic conditions prevailing in Germany because of their late ripening. Because of the presumably lower demands on maturation during utilization in biogas plants, the suitability of varieties with a slightly higher number of maturities is being investigated. Due to their longer vegetation period , they can deliver higher biomass yields.
  • When harvesting, in particular drier, more mature material, the chopping length is reduced in order to increase the area of ​​attack for the enzymatic breakdown in the fermenter of the biogas plant and thus to accelerate and improve it.

sorts

So far, the varieties that have proven themselves in silage maize cultivation have generally been grown. The advantages of conventional varieties over energy maize varieties are the earlier harvest, e.g. B. before sowing winter cereals , as well as in the more flexible usability. However, the less stringent demands placed on energy maize also open up new breeding opportunities. In a joint project by the Agency for Renewable Raw Materials (FNR), KWS SAAT AG , the University of Hohenheim and the Bavarian State Research Center for Agriculture , the potential yield was increased by around 20 to 25% (by 40 to 50 dt dry matter / ha) within five years. can be achieved. The aim of the project is to almost double the yield in 10 years. The great genetic variability of maize was or is being used to breed these high-yielding, hybrid maize varieties in the short term . Important properties that have been combined in the energy maize varieties and to be include high dry matter yield, Kurztagadaption , cold tolerance, drought resistance , etc.

economics

Maize silage is generally considered to be the most economical biogas substrate when measured by comparing the production costs with the energy yield from the gas . Depending on the relationship between the market prices of possible input materials and operational conditions such as climate and soil conditions, crop rotation, plant technology and the availability of free substrates, the use of other substrates (e.g. grass silage , millet types , liquid manure , poultry manure , grain) can be similar or higher Profits are made.

The energy yield of maize, based on the irradiated sunlight, is much smaller than the energy yield of commercially available photovoltaic modules. While the annual yield of one square meter of energy maize can only be generated from 1.5 to 2.25 kWh for maize according to figures from the FNR, the yield of an average square meter of open space photovoltaics is at least 31 times higher at over 70 kWh.

The electricity production costs of energy maize are between 15 and 30 ct / kWh, depending on the size of the plant. The tenders for open space photovoltaics were drawn in 2019 at around 5ct / kWh.

The advantage of energy maize as a renewable energy source is its storability and the associated potential for demand-oriented electricity generation without additional energy storage.

criticism

The cultivation of maize was greatly expanded for the use of maize in biogas plants. In 2007 energy maize accounted for 12.8% of the maize cultivation area in Germany, in 2011 it was already 22% and in 2018 it was 41%. With the EEG amendment in 2012, the use of maize in new and existing plants was restricted for the first time ("maize lid") in order to counteract this development. Further restrictions followed in the 2017 EEG amendment; the use of corn and grain gradually up to max. 44% in 2021.

The Wildlife Protection Society of Germany (NABU) and the German Association for Nature Management (DVL) criticized the change of the landscape through more corn and scenic and ecological consequences of grassland as Vermaisung . In 2013 around 2.49 million hectares of maize were cultivated in Germany. 47% was silage maize for animal feeding, 33% energy maize and 20% grain maize , which means the distribution remained exactly the same as in the previous year. In the individual federal states, however, the distribution differs greatly from the national average. For example, while 49% of the maize in Mecklenburg-Western Pomerania is used as energy maize, in Rhineland-Palatinate it is only 13%.

According to the energy maize cultivation, like the cultivation of other energy crops, is associated with soil erosion, water pollution and a decline in biodiversity . Food, and especially animal feed, may have to be imported from developing countries where rainforest may fall victim to cultivation. According to Stefan Klotz , head of the vegetation dynamics working group at the Reinhold-Tüxen-Gesellschaft , the cultivation of energy crops is ineffective and the side effects of cultivation are all the greater.

The general criticism of the cultivation of energy crops because of the increasing competition for land, for example for food and feed production, is also shared by NABU, and environmentally friendly cultivation is proclaimed. The German Maiskomitee dismissed in 2010. warnings of a "Vermaisung" with reference to a maize-growing area of less than 10% of the agricultural land in Germany back.

In the wake of the heavy rain storms in Germany in 2016, voices were voiced by experts who blamed the increased cultivation of maize, as this reduced the soil's ability to absorb water. Other experts consider this connection to be exaggerated.

Alternatives and supplements to growing corn

In order to avoid corn monocultures , there are various efforts to make other crops such as sunflowers and sugar beet usable for biogas production. Since corn can be sown late as thermophilic plant is attempted, the growing season , such as green rye as a cover crop for the production of whole plant silage to achieve (GPS) to better utilize and thus higher yields per unit area and year. Another advantage is that the winter ground cover reduces nutrient losses and erosion . Also catch crops , eg. B. to avoid erosion, and higher stand densities are possible.

Since 2005, ecological and economic aspects of the cultivation of energy crops have been investigated in an extensive joint project. Various energy crop rotations are being tested in six typical growing regions in Germany, including both the crops that are common today and possible alternatives. Numerous other projects in the field of alternative and sustainable cultivation methods for energy crops are coordinated by the FNR.

Due to the low efficiency, combined with the side effects, the cultivation of energy maize is not a solution for sustainable energy supply, but the use of residues from animal husbandry and food production is an alternative that has not yet been widely used. The cultivation of perennial crops, wild plants and, for example, Silphium perfoliatum is also being investigated. The latter delivers similarly high yields, but shows ecological advantages over maize

Individual evidence

  1. ↑ Fachagentur Nachwachsende Rohstoffe e. V. (FNR): Biogas basic data Germany. (PDF; as of October 2008). Source for all information except for pressed pulp.
  2. ↑ Biogas yields of different substrates, division potatoes / beets lfl.bayern.de, see pressed pulp ensiled .
  3. ↑ Current figures on acreage and general information on maize - DBV, accessed in August 2012
  4. ↑ a b c d Production technology for energy maize: Information from the Saaten-Union on energy maize cultivation from January 9, 2007 ( memento of the original from February 23, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.saaten-union.de
  5. ↑ KWS Saat AG: Cultivation Guide for Biogas Production 2009 ( Memento of the original from March 11, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , available as pdf, accessed March 6, 2010 @1@ 2Template: Webachiv / IABot / www.kws.de
  6. ↑ a b c Chamber of Agriculture Schleswig-Holstein: When the silo “starts to run” ... - A safer way to avoid the source of leakage seepage , report in Landpost , dated January 2, 2010, accessed on March 6, 2010
  7. ↑ a b Chamber of Agriculture North Rhine-Westphalia : State trials of medium-late maize varieties / Biogasmais 2008 ( Memento from May 22, 2009 in the Internet Archive ), from January 5, 2009, accessed on October 5, 2015.
  8. ↑ a b c d Status of energy maize breeding at KWS SAAT AG, lecture at the 2nd Einbecker Energy Plants Colloquium on 5./6. November 2007 ( Memento of the original from February 23, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.kws.de
  9. ↑ http://www.innovations-report.de : Energiemais: environmentally friendly cultivation with high yields , report from July 6, 2004, accessed on March 5, 2010
  10. ^ Chamber of Agriculture Lower Saxony, 2009: What alternatives to maize may cost. Retrieved April 14, 2009
  11. ↑ a b Figures from the specialist agency for renewable raw materials e. V. for biogas , accessed on July 6, 2018
  12. ↑ www.maiskomitee.de ( Memento from April 20, 2009 in the Internet Archive )
  13. ↑ Agency for Renewable Raw Materials (FNR): Three quarters of maize is animal feed. In: ErneuerbareEnergien.de. Retrieved January 23, 2019 .
  14. ↑ dmk: Corn cultivation area stable. April 26, 2018, accessed January 23, 2019 .
  15. ↑ René Walter (on behalf of the Fachverband Biogas eV): Production and feed-in of biogas and the EEG 2012. In: Clearingstelle EEG. Retrieved January 23, 2019 .
  16. ↑ EEG 2017: This is changing for biogas plant operators. January 2, 2017, accessed January 23, 2019 .
  17. ↑ One third of the maize cultivation area for biogas . German Maiskommitee . Retrieved November 2, 2013.
  18. ↑ a b c https://www.spektrum.de/news/bioenergie-aus-mais-ist-umweltschaedlich/1422993 Kerstin Vierling: On the way to the corn desert ?, accessed on July 7, 2018
  19. ↑ https://www.nabu.de/imperia/md/content/nabude/energie/19.pdf NABU basic program energy, accessed on July 7, 2018
  20. ↑ https://www.topagrar.com/news/Home-top-News-DMK-Es- htt- keine-Vermaisung-in-Deutschland-122261.html DMK: There is no "corning" in Germany , published 25. Jan. 2010, accessed July 7, 2018
  21. ↑ Archive link ( Memento of the original from August 17, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.br.de
  22. ↑ http://www.mdr.de/ffekt/ffekt-hochwasser-simbach-maisanbau-100.html
  23. ↑ Information from the Saaten-Union on the cultivation of green rye for biogas production from July 13, 2007 ( Memento of the original from February 23, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.saaten-union.de
  24. ↑ Saaten-Union GmbH: Undersown crops, inexpensive and effective ( Memento of the original dated December 12, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , dated February 5, 2007, accessed March 5, 2010 @1@ 2Template: Webachiv / IABot / www.saaten-union.de
  25. ↑ Information on the project "Development and comparison of optimized cultivation systems for the agricultural production of energy crops under the various local conditions in Germany" (EVA) of the Fachagentur Nachwachsende Rohstoffe e. V. (FNR) ( Memento from December 15, 2009 in the Internet Archive )
  26. ↑ Fachagentur Nachwachsende Rohstoffe e. V. (FNR): Current projects of the Federal Ministry of Food, Agriculture and Consumer Protection in the field of "Renewable Raw Materials" ( Memento from April 1, 2009 in the Internet Archive ), FNR project database
  27. ↑ Pilot project: Mixed Silphie can keep up with maize in terms of yield. October 4, 2018, accessed January 23, 2019 .
  28. ↑ Studies on the ecological effect of the streaky Silphie from Bavaria - Journal for Cultivated Plants. Retrieved January 23, 2019 .
  29. ↑ Agro- ecological evaluation of the streaky Silphie (Silphium perfoliatum L.) as a biomass plant of the future. Johann Heinrich von Thünen Institute and Julius Kühn Institute Federal Research Institute for Cultivated Plants, accessed on January 23, 2019 .

literature

  • Fachagentur Nachwachsende Rohstoffe eV (FNR): Handout Biogas Production and Use , 3rd Edition (2006), 232 pp. ISBN 3-00-014333-5 ( PDF document )
  • KTBL : Energy crops - data for planning energy crops , Darmstadt (2006), ISBN 978-3939371212
  • Fachagentur Nachwachsende Rohstoffe eV (FNR): Location-adapted cultivation systems for energy crops , 3rd modified and expanded edition (2010), 119 pages, i.e. available in PDF format

Web links