Energy return on investment

In energy economics and ecological energetics, energy return on investment (EROI), also sometimes called energy returned on energy invested (ERoEI), is the ratio of the amount of usable energy (the exergy) delivered from a particular energy resource to the amount of exergy used to obtain that energy resource.^[1]

Arithmetically the EROI can be defined as:

EROI={\frac {\hbox{Energy Delivered}}{\hbox{Energy Required to Deliver that Energy}}}

.^[2]

When the EROI of a source of energy is less than or equal to one, that energy source becomes a net "energy sink", and can no longer be used as a source of energy. A related measure, called energy stored on energy invested (ESOEI), is used to analyse storage systems.^[3]^[4]

To be considered viable as a prominent fuel or energy source a fuel or energy must have an EROI ratio of at least 3:1.^[5]^[2]

^ Murphy, D.J.; Hall, C.A.S. (2010). "Year in review EROI or energy return on (energy) invested". Annals of the New York Academy of Sciences. 1185 (1): 102–118. Bibcode:2010NYASA1185..102M. doi:10.1111/j.1749-6632.2009.05282.x. PMID 20146764. S2CID 6433639.
^ ^a ^b Hall, CA; Lambert, JG; Balogh, SB (2013). "EROI of different fuels and the implications for society". Energy Policy. 64: 141–52. doi:10.1016/j.enpol.2013.05.049.
^ "Why energy storage is a dead-end industry - Energy Storage Report". 15 October 2014.
^ Barnhart, Charles J.; Dale, Michael; Brandt, Adam R.; Benson, Sally M. (2013). "The energetic implications of curtailing versus storing solar- and wind-generated electricity". Energy Environ. Sci. 6 (10): 2804–10. doi:10.1039/c3ee41973h.
^ Atlason, R; Unnthorsson, R (2014). "Ideal EROI (energy return on investment) deepens the understanding of energy systems". Energy. 67: 241–45. Bibcode:2014Ene....67..241A. doi:10.1016/j.energy.2014.01.096.

[mh2010-1] Murphy, D.J.; Hall, C.A.S. (2010). "Year in review EROI or energy return on (energy) invested". Annals of the New York Academy of Sciences. 1185 (1): 102–118. Bibcode:2010NYASA1185..102M. doi:10.1111/j.1749-6632.2009.05282.x. PMID 20146764. S2CID 6433639.

[Hall_CA_2013-2] Hall, CA; Lambert, JG; Balogh, SB (2013). "EROI of different fuels and the implications for society". Energy Policy. 64: 141–52. doi:10.1016/j.enpol.2013.05.049.

[3] "Why energy storage is a dead-end industry - Energy Storage Report". 15 October 2014.

[c3e-4] Barnhart, Charles J.; Dale, Michael; Brandt, Adam R.; Benson, Sally M. (2013). "The energetic implications of curtailing versus storing solar- and wind-generated electricity". Energy Environ. Sci. 6 (10): 2804–10. doi:10.1039/c3ee41973h.

[5] Atlason, R; Unnthorsson, R (2014). "Ideal EROI (energy return on investment) deepens the understanding of energy systems". Energy. 67: 241–45. Bibcode:2014Ene....67..241A. doi:10.1016/j.energy.2014.01.096.

[1]

[2]

[3]

[4]

[5]