This article needs additional citations for verification. (April 2012) (Learn how and when to remove this template message)
Energy crops are crops grown solely for energy. Commercial energy plantations are typically densely planted and high-yielding. The crops are processed into solid, liquid or gaseous fuels, which are later burned to generate power or heat.
The plants are generally categorized as woody or herbaceous. Woody plants include willow and poplar, herbaceous plants include Miscanthus x giganteus and Pennisetum purpureum (both known as elephant grass). Herbaceous crops, while physically smaller than trees, store roughly twice the amount of CO2 (in the form of carbon) below ground, compared to woody crops.
Through biotechnological procedures such as genetic modification plants can be manipulated to create higher yields. Relatively high yields can also be realized with existing cultivars.:250 However, some additional advantages such as reduced associated costs (i.e. costs during the manufacturing process ) and less water use can only be accomplished by using genetically modified crops.
Solid biomass, often pelletized, is used for combustion in thermal power stations, either alone or co-fired with other fuels. Alternatively it may be used for heat or combined heat and power (CHP) production.
In short rotation coppice (SRC) agriculture, fast growing tree species like willow and poplar are grown and harvested in short cycles of three to five years. These trees grow best in wet soil conditions. An influence on local water conditions can not be excluded. Establishment close to vulnerable wetland should be avoided.
Gas biomass (methane)Edit
Whole crops such as maize, Sudan grass, millet, white sweet clover, and many others can be made into silage and then converted into biogas.Anaerobic digesters or biogas plants can be directly supplemented with energy crops once they have been ensiled into silage. The fastest growing sector of German biofarming has been in the area of "Renewable Energy Crops" on nearly 500,000 ha (1,200,000 acres) of land (2006). Energy crops can also be grown to boost gas yields where feedstocks have a low energy content, such as manures and spoiled grain. It is estimated that the energy yield presently of bioenergy crops converted via silage to methane is about 2 GWh/km2 (1.8×1010 BTU/sq mi) annually. Small mixed cropping enterprises with animals can use a portion of their acreage to grow and convert energy crops and sustain the entire farms energy requirements with about one fifth of the acreage. In Europe and especially Germany, however, this rapid growth has occurred only with substantial government support, as in the German bonus system for renewable energy. Similar developments of integrating crop farming and bioenergy production via silage-methane have been almost entirely overlooked in N. America, where political and structural issues and a huge continued push to centralize energy production has overshadowed positive developments.
European production of biodiesel from energy crops has grown steadily in the last decade, principally focused on rapeseed used for oil and energy. Production of oil/biodiesel from rape covers more than 12,000 km² in Germany alone, and has doubled in the past 15 years. Typical yield of oil as pure biodiesel may be is 100,000 L/km2 (68,000 US gal/sq mi; 57,000 imp gal/sq mi) or more, making biodiesel crops economically attractive, provided sustainable crop rotations exist that are nutrient-balanced and preventative of the spread of disease such as clubroot. Biodiesel yield of soybeans is significantly lower than that of rape.
Energy crops for biobutanol are grasses. Two leading non-food crops for the production of cellulosic bioethanol are switchgrass and giant miscanthus. There has been a preoccupation with cellulosic bioethanol in America as the agricultural structure supporting biomethane is absent in many regions, with no credits or bonus system in place. Consequently, a lot of private money and investor hopes are being pinned on marketable and patentable innovations in enzyme hydrolysis and the like.
Bioethanol also refers to the technology of using principally corn (maize seed) to make ethanol directly through fermentation, a process that under certain field and process conditions can consume as much energy as is the energy value of the ethanol it produces, therefore being non-sustainable. New developments in converting grain stillage (referred to as distillers grain stillage or DGS) into biogas energy looks promising as a means to improve the poor energy ratio of this type of bioethanol process.
Energy crop use in various countriesEdit
In Sweden, willow and hemp are often used.
- Mola-Yudego, Blas & Aronsson, Pär. (2008). Yield models for commercial willow biomass plantations in Sweden. Biomass and Bioenergy. 32. 829-837. https://doi.org/10.1016/j.biombioe.2008.01.002
- «In conclusion, the annual net SOC [soil organic carbon] storage change exceeds the minimum mitigation requirement (0.25 Mg C ha−1 year−1)[0.25 metric tons carbon per hectare per year] under herbaceous and woody perennials by far (1.14 to 1.88 and 0.63 to 0.72 Mg C ha−1 year−1, respectively).» Agostini F, Gregory AS, Richter GM. Carbon Sequestration by Perennial Energy Crops: Is the Jury Still Out?. Bioenergy Res. 2015;8:1057–1080, page 1057. doi:10.1007/s12155-014-9571-0 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4732603/ This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
- Ara Kirakosyan; Peter B. Kaufman (2009-08-15). Recent Advances in Plant Biotechnology. p. 169. ISBN 9781441901934. Retrieved 14 February 2013.
- An example here is [https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-017-0793-1 CINNAMOYL-CoA REDUCTASE maize
- Hartwich, Jens (2017). "Assessment of the regional suitability of short rotation coppice in Germany (PDF Download Available)". Doctoral Thesis. Freie Universität Berlin. Institut für Geographische Wissenschaften. doi:10.13140/rg.2.2.17825.20326 – via ResearchGate.
- Hartwich, Jens; Bölscher, Jens; Schulte, Achim (2014-09-19). "Impact of short-rotation coppice on water and land resources". Water International. 39 (6): 813–825. doi:10.1080/02508060.2014.959870. ISSN 0250-8060.
- Hartwich, Jens; Schmidt, Markus; Bölscher, Jens; Reinhardt-Imjela, Christian; Murach, Dieter; Schulte, Achim (2016-07-11). "Hydrological modelling of changes in the water balance due to the impact of woody biomass production in the North German Plain". Environmental Earth Sciences. 75 (14): 1–17. doi:10.1007/s12665-016-5870-4. ISSN 1866-6280.
- "Environmental Use of BioMass".
- Umer. "Bio Mass Energy".
- Handbook for energy producers
- GA Mansoori, N Enayati, LB Agyarko (2016), Energy: Sources, Utilization, Legislation, Sustainability, Illinois as Model State, World Sci. Pub. Co., ISBN 978-981-4704-00-7
- Energy Crops for Fuel
- Energy crops at Biomass Energy Centre
- Center for Sustainable Energy Farming
- Reviewing the scientific evidence about ecological impacts of renewables