Page 400 - A Comprehensive Guide to Solar Energy Systems

Chapter 21 • (EROI) and (EPBT) for PVs 409

FIGURE 21.1 Energy output versus EROI for various energy sources. Adapted from Hall CAS. Energy return on
investment: a unifying principle for biology, economics, and sustainability. Springer Nature, Lecture Notes in
Energy, vol. 36. Cham: Springer International Publishing AG; 2017 and concept from Euan Mearns. As the EROI
approaches 1:1 the ratio of energy gained to energy consumed in the process decreases exponentially [13].
Whereas high EROI fuels deliver a greater proportion of their energy to society, low EROI fuels deliver a much
smaller proportion of their energy to society.
21.2 Methods of EROI Analysis
21.2.1 Introduction to Methods of EROI Analysis

To get the best information from a solar pv EROI analysis, one should strive for a well­
defined system within a well­defined set of boundaries and good data. Unfortunately,
much of the questions surrounding pv technologies and deployment are from an indus­
try­wide or nationwide point of view. These questions have always been more difficult
to answer with EROI analysis, as they inherently require more data and usually more
assumptions to obtain a complete picture. EROI analysis is not a precision science, how­
ever, with attention to assumptions and uncertainties involved, reasonably accurate and
repeatable results can be obtained to answer important and specific questions.
The first formal protocol for developing EROI analysis was published by murphy and
Hall [14], which provides a general overview on how to proceed toward a “standard” EROI
calculation. The standard EROI calculation has its output boundary set at the wellhead,
farm gate, buss bar, or other source. For example, when calculating the standard EROI for
crude oil, the boundary is at the wellhead, or where the oil comes out of the ground. The
subsequent activities of storing, transporting, and refining the crude oil are not included