High Life Cycle Efficacy Explains Fast Energy Payback for Improved Off-Grid Lighting Systems


Peter Alstone*, Patricia Lai#, Evan Mills† and Arne Jacobson#


* Energy and Resources Group, University of California at Berkeley, USA
 Lawrence Berkeley National Laboratory, University of California, USA
# Schatz Energy Research Center, Humboldt State University, USA


Lumina Project Technical Report #9


March 2014


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The energy intensity of fuel-based lighting is substantial given the paltry levels of lighting service, poor economic outcomes, and exposure to public health risks for users throughout the developing world. There is a great opportunity to reduce fossil energy consumption (and mitigate greenhouse gas emissions) while improving public health and economic outcomes for the poor by encouraging upgrading from fuel-based to rechargeable light-emitting diode (LED) lighting. However, switching to efficient lighting requires up-front investments of energy for manufacturing. This study explores life cycle energy performance in the market for modern off-grid lighting (OGL) products in Sub-Saharan Africa and introduces a new metric, life cycle efficacy, which facilitates comparisons and analysis of life cycle energy performance (light output per unit of embodied plus use-phase energy consumption) for lighting technology systems. Combining field insights on technology adoption dynamics with embodied energy estimates for a range of products available in 2012 shows that OGL energy “debts” are “paid back” in 20 to 50 days (substantially faster than kilowatt-scale grid-connected solar electricity systems) with energy return on investment ratios from 10 to 40. This stems from greatly improved life cycle efficacy for off-grid LED lighting (20 lumens/watt [lm/W]), compared to fuel-based lighting (0.04 lumens/W). Life cycle benefits—not only energy, but also economic and health benefits—depend strongly on product service lifetime (related to quality) and fuel displacement fraction (related to performance). OGL life cycle efficacy increases from longer lifetime and/or improved LED source efficacy lead to better quality and less-expensive lighting available in the developing world with lower energy use than the fuel-based incumbent technology.


Acknowledgments: This work was funded by The Rosenfeld Fund of the Blum Center for Developing Economies at University of California, Berkeley, through the USDOE (under contract no. DE-AC02– 05CH11231), and by the Lighting Africa Program, a joint IFC World Bank initiative. Support for P.A. was provided by a U.S. Environmental Protection Agency STAR Fellowship for Graduate Environmental Study, and support for P.L. was provided by the National Science Foundation Science Masters Program. Art Rosenfeld has been a key supporter of this work.

About The Lumina Project

The Lumina Project—an initiative of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory—provides industry, consumers, and policymakers with timely analysis and information on off-grid lighting solutions for the developing world. Lumina Project activities combine laboratory and field-based investigations to ensure the formation of policies and uptake of products that maximize consumer acceptance and energy savings. For more information, please visit http://light.lbl.gov