The Energy Return on Energy Invested (EROI or EROEI) is the amount of
energy acquired from a particular energy source divided by the energy
expended, or invested, in obtaining that energy. EROI is an essential
and seemingly simple measure of the usable energy or "energy profit"
from the exploitation of an energy source, but it is not so easy to
determine all of the energy expenditures that should be included in the
calculation. Because EROI values are generally low for renewable energy
sources, differences in these estimates can lead to sharply divergent
conclusions about the viability of these energy technologies. This book
presents the first complete energy analysis of a large-scale, real-world
deployment of photovoltaic (PV) collection systems representing 3.5 GW
of installed, grid-connected solar plants in Spain. The analysis
includes all of the factors that limit and adjust the real electricity
output through one full-year cycle, and all of the fossil fuel inputs
required to achieve these results. The authors' comprehensive analysis
of energy inputs, which assigns energy cost estimates to all financial
expenditures, yields EROI values that are less than half of those
claimed by other investigators and by the solar industry. Sensitivity
analysis is used to test various assumptions in deriving these EROI
estimates. The results imply that the EROI of current, large-scale PV
systems may be too low to seamlessly support an energy and economic
transition away from fossil fuels. Given the pervasiveness of fossil
fuel subsidies in the modern economy, a key conclusion is that all
components of the system that brings solar power to the consumer, from
manufacturing to product maintenance and life cycle, must be improved in
terms of energy efficiency. The materials science of solar conversion
efficiency is only one such component.
Sunny Spain represented an ideal case study as the country had the
highest penetration of solar PV energy at 2.3 percent of total national
demand as well as state-of-the-art expertise in solar power including
grid management of intermittent, modern renewable systems. This book,
written by a uniquely qualified author team consisting of the chief
engineer for several major photovoltaic projects in Spain and the
world's leading expert on the concept and application of EROI, provides
a comprehensive understanding of the net energy available to society
from energy sources in general and from functioning PV installations
under real-world conditions in particular. The authors provide critical
insight into the capacity of renewable energy sources to fill the
foreseeable gap between world energy demand and depletion rates for
fossil fuels.
- Presents the first comprehensive study of the EROI of large-scale
solar PV systems in a developed country
- Uses real-world operational data rather than laboratory
approximations and extrapolations
- Describes the dependence of one alternative energy source on the
goods and services of a fossil-fueled economy
- Has global implications for the potential of renewable energy sources
to replace dwindling reserves of fossil fuels
- Written with the first-hand knowledge of the chief, on-site engineer
for many solar installations in Spain together with the leader in the
development and application of the concept of EROI
