sustainability - SUNY College of Environmental Science and Forestry

Sustainability 2011 , 3 , 2433-2442; doi:10.3390/su3122433

sustainability

ISSN 2071- 1050

http://www.mdpi.com/journal/sustainability

Article

Implications of Energy Return on Energy Invested on Future

Total Energy Demand

Shinuo Deng and George R. Tynan *

Center for Energy Research and Department of Mechanical and Aerospace Engineering UCSD,

9500 Gilman Drive, La Jolla, CA 92093, USA

* Author to whom correspondence should be addressed; E-Mail: [email protected];

Tel.: +1-858-534-9724; Fax: +1-858-534-7716.

Received: 5 January 2011; in revised form 10 July 2011 / Accepted: 10 November 2011 /

Published: 13 December 2011

Abstract: Human society is now at the beginning of a transition from fossil-fuel based

primary energy sources to a mixture of renewable and nuclear based energy sources which

have a lower Energy Return On Energy Invested (EROEI) than the older fossil based

sources. This paper examines the evolution of total energy demand during this transition for

a highly idealized energy economy. A simple model is introduced in which the net useful

energy output required to operate an economy is assumed to remain fixed while the lower

EROEI source gradually replaces the older higher EROEI primary energy source following

a logistics subst itution model. The results show that, for fixed net useful energy output, total

energy demand increases as the ratio EROEInew/EROEIold decreases; total energy demand

diverges as EROEInew approaches unity, indicating that the system must collapse in

this limit.

Keywords: EROEI; energy demand; total energy demand

1. Introduction

Energy plays a critical role in enabling and sustaining human societies and is subject to strict

physical conservation laws arising from thermodynamics. Human society is now at the beginning of a

transit ion fro m fossil-fuel based primary energy sources to a mixture of renewable and nuclear based

energy sources which have a lower Energy Return On Energy Invested (EROEI) than the older fossil

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Reprinted fromSustainability. Cite as: Deng, S.; Tynan, G.R. Implications of Energy Return on Energy
Invested on Future Total Energy Demand.Sustainability 2011 , 3 , 2433-2442; doi:10.3390/su3122433.

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