A general mathematical framework for calculating systems-scale efficiency of energy extraction and conversion: Energy return on investment (EROI) and other energy return ratios

Energies

Volumn 4, Issue 8, 2011, Pages 1211-1245

  Brandt, Adam R ^a   Dale, Michael ^a  

^a STANFORD UNIVERSITY   (United States)

Author keywords

Energy efficiency; Energy quality; Energy return on investment

Indexed keywords

ENERGY EFFICIENCY; ENERGY HARVESTING; ENERGY UTILIZATION; EXTRACTION; LIFE CYCLE; NETWORK FUNCTION VIRTUALIZATION; PROFITABILITY;

CONVERSION SYSTEMS; ECONOMIC APPROACH; ENERGY QUALITY; ENERGY RETURN ON INVESTMENTS; LIFE CYCLE ANALYSIS; MATHEMATICAL FORMS; MATHEMATICAL FRAMEWORKS; NET ENERGY RATIOS;

INVESTMENTS;

EID: 80052808553     PISSN: None     EISSN: 19961073     Source Type: Journal    
DOI: 10.3390/en4081211     Document Type: Article

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40. It is noted here that energy is never truly "consumed" due to the first law of thermodynamics. This terminology is used throughout to refer to the degradation of useful energy to waste heat, or the destruction of exergy during an energy conversion process.
41. s,s also cannot be incorporated into the output energy stream. In some real-world cases, this assumption is violated, as when an oil refinery incorporates energy from natural-gas-derived hydrogen into the finished product stream.
42. Using the EIO LCA tool, very little biomass energy is consumed indirectly in natural gas production. In rounding to two significant figures, no biomass energy is consumed.
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47. α is derived from an energy balance on a pathway with no external consumption, as illustrated in the appendix
48. This quantity has been called by a number of names, including Process Net Energy Ratio (PNER) , energy yield ratio (EYR) and net energy ratio (NER). The same CERI report also defines a related metric called the Resource Net Yield Ratio that includes in the denominator energy lost or rendered unrecoverable through the extraction process. Metrics also differ by whether they consider the gross or net output from a process.
49. In other studies, this quantity is variously called the incremental energy ratio, or IER [1], or the external net energy ratio (ENER)
50. Note that methods for calculating EROI have varied significantly to date, but this metric seems the most congruent with the general goals of EROI analysis
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53. 3,j flows are unknown
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60. This is a common feature of mathematical models with "recycle" loops (e.g., chemical engineering systems with recycle of unreacted product).