A Review of Renewable Sources of Electricity Derived from
Natural Energy Flows
Authors: C. Neumeyer
Abstract: Amongst the sources of renewable energy
are those driven by natural energy flows including solar radiation
(solar energy and its derivatives), geothermal heat (from the
interior of the earth), and gravitational energy (mainly from the
moon) [1], in order of annual flow capacity:
None of the above sources rely on the combustion of organic
materials, and none are exhaustible on a human time scale. Thus
they offer the potential to contribute to an ideal sustainable,
carbon-free energy future.
Prospects for utilization of these sources for electricity generation depend on various interrelated technical, economic, and social factors. Technical factors include resource availability, characteristics of conversion technology, compatibility with the electrical grid, and life cycle energy gain. Economic factors include the inherent cost of deployment along with subsidies or penalties imposed by governmental institutions. Social factors encompass a range of human and environmental considerations. In this review we address primarily the technical factors, but economic and environmental factors are mentioned. Our objective is to assess feasibility and risks in the context of plans for a major expansion of the role of renewables in the energy portfolio of the 21st century.
We provide a brief review of renewable sources, their energy
capture and conversion systems, and a comparative summary of key
metrics. We discuss the benefits and challenges including issues
related to integration into the power grid. We then consider plans
for future expansion of renewables in the US as envisioned in a
study by the National Renewable Energy Laboratory (NREL) along
with scenarios developed under the auspices of the
Intergovernmental Panel on Climate Change (IPCC) covering the
global supply of electricity, indentifying risks that could impede
the plans.
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