title: Changing pollutants to green biogases for the crop food cycle chain.
abstract: OBJECTIVE
  When fossil fuels on the Earth are used up, which kind of green energy can be used to replace them? Do every bioenergy generation or crop food chain results in environmental pollution? These questions are major concerns in a world facing restricted supplies of energy and food as well as environmental pollutions. To alleviate these issues, option biogases are explored in this paper.
  
  
  METHODS
  Two types of biogas generators were used for modifying the traditional crop food chain [viz. from atmospheric CO(2) photosynthesis to crops, crop stem/husk biowastes (burnt in cropland or as home fuels), to livestock droppings (dumping away), pork and people foods, then to CO(2)], via turning the biowaste pollutants into green bioenergies. By analyzing the traditional food chain via observation method, the drawbacks of by-product biowastes were revealed. Also, the whole cycle chain was further analyzed to assess its "greenness," using experimental data and other information, such as the material balance (e.g., the absorbed CO(2), investment versus generated food, energy, and wastes).
  
  
  CONCLUSIONS
  The data show that by using the two types of biogas generators, clean renewable bioenergy, crop food, and livestock meat could be continuously produced without creating any waste to the world. The modification chain largely reduced CO(2) greenhouse gas and had a low-cost investment. The raw materials for the gas generators were only the wastes of crop stems and livestock droppings. Thus, the recommended CO(2) bioenergy cycle chain via the modification also greatly solved the environmental biowaste pollutions in the world.
  
  
  CONCLUSIONS
  The described two type biogases effectively addressed the issues on energy, food, and environmental pollution. The green renewable bioenergy from the food cycle chain may be one of suitable alternatives to fossil and tree fuels for agricultural countries.
authors.affiliation: Chemical & Environmental Engineering Department, National University of Singapore, Singapore, Singapore. zong_baoyu@dsi.a-star.edu.sg
authors.forename: B Y
authors.initials: BY
authors.lastname: Zong
authors.forename: F J
authors.initials: FJ
authors.lastname: Xu
authors.forename: B D
authors.initials: BD
authors.lastname: Zong
authors.forename: Z G
authors.initials: ZG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D056804:Biofuels; D018533:Biomass; D018556:Crops, Agricultural; D005243:Feces; D020387:Food Chain; D058751:Livestock; D008460:Meat; D059205:Renewable Energy; D014866:Waste Products
chemical_list: D056804:Biofuels; D014866:Waste Products