Bioenergy production from algae using dairy manure as a nutrient source: Life cycle energy and greenhouse gas emission analysis q Raja Chowdhury a,⇑ , Fausto Freire b a Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India b ADAI–LAETA, Dept. of Mechanical Engineering, University of Coimbra, Polo II Campus, Rua Luis Reis Santos, Coimbra 3030-788, Portugal highlights  0.56 billion GJ energy can be produced Using dairy nutrients produced in USA.  Energy requirement (ER), GHG emissions of produced bioenergy are lower than reported study.  Incorporating nutrient value of residues has no effect on ER of produced bioenergy.  Significant increase in bioenergy production was observed in year round operation.  Technological breakthrough extent of biomass processing affect bioenergy production. graphical abstract Dairy Manure Anaerobic digeson Algal biodiesel producon Bioenergy Land applicaon of residual biomass/biochar/sludge Effluent Bioenergy Pyrolysis Anaerobic digeson of residual biomass, sludge Enzymac hydrolysis Sludge article info Article history: Received 30 September 2014 Received in revised form 24 April 2015 Accepted 15 May 2015 Available online xxxx Keywords: Dairy manure Algal bioenergy Life cycle assessment (LCA) Energy demand Greenhouse gas (GHG) abstract This study estimated the potential of algal bioenergy production using nitrogen and phosphorus present in the dairy manure (produced in the US). State wise dairy manure production and energy mixes were used to estimate algal bioenergy production and associated life cycle nonrenewable primary energy demand and greenhouse gas emissions for the four scenarios. These scenarios were constructed using various combination of following processes (i) anaerobic digestion, (ii) algal biodiesel production using effluent from (i), (iii) pyrolysis, and (iv) enzymatic hydrolysis. Bioenergy production, nonrenewable pri- mary energy demand and greenhouse gas emissions of each state were aggregated to estimate the total bioenergy production, nonrenewable primary energy requirement and greenhouse gas emissions for the US. Two different cases were simulated for each scenario, one without taking into account the nutrient values (N, P) of applied sludge generated from the bioenergy production (Case B) while in the other one, nutrient values of sludge were considered (Case A). For incorporation of nutrient values of sludge, system expansion approach was used. It was estimated that by using dairy manure, 0.56 billion GJ/yr bioenergy could be produced. Minimum ‘‘nonrenewable primary energy requirement (NRPER)’’ (GJ/GJ) [Total primary nonrenewable energy requirement/bioenergy produced] and GHG emissions (kg CO 2 eq./GJ bioenergy produced) for the four scenarios (1–4) for case B were as follows (1) 0.37, 27 (2) 0.51, 30; (3) 0.55, 47 and (4) 0.70, 15 respectively. In case A, NRPER did not change as compared to case B. http://dx.doi.org/10.1016/j.apenergy.2015.05.045 0306-2619/Ó 2015 Elsevier Ltd. All rights reserved. q This paper is included in the Special Issue of Life Cycle Analysis and Energy Balance for algal biofuels and for biomaterials edited by Dr. Kyriakos Maniatis, Dr. Mario Tredici, Dr. David Chiaramonti, Dr. Vitor Verdelho and Prof. Yan. ⇑ Corresponding author. E-mail addresses: rajacfce@iitr.ernet.in (R. Chowdhury), fausto.freire@dem.uc.pt (F. Freire). Applied Energy xxx (2015) xxx–xxx Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy Please cite this article in press as: Chowdhury R, Freire F. Bioenergy production from algae using dairy manure as a nutrient source: Life cycle energy and greenhouse gas emission analysis. Appl Energy (2015), http://dx.doi.org/10.1016/j.apenergy.2015.05.045