Quote:
Originally Posted by Slowhand
The ability (or lack of the ability) to store electricity is the limiting factor in all the renewable energy sources. The Government should start a Manhattan Project to develop new battery storage technology that holds vast amounts of electricity for long time periods. This would help all types of renewable energy.
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Slowhand, also please bear in mind that Solar Thermal heat storage technology is now available and looks to be cost competitive all relevant factors considered. Apparently far cheaper than battery storage for kwh of stored energy and even when converted into electrical energy it's still several times cheaper over the long term. 
Make of it what you will, but there are some very interesting reads here for those interested in this topic.
Summary of the Solar Two Test and Evaluation Program
SAND2000-0372C Received Feb 24 2000 OSTI
http://www.osti.gov/bridge/servlets/...ble/751185.pdf
Solar Two - Solar Power Tower - FAQ
Quote:
Demonstrated a 97% Energy-Storage Efficiency
http://www.azsolarcenter.com/links/faqs/solar.pdf
Quote:
Storage Efficiency was measured at over 97%, also meeting design goals.
The
SOLARTRES ( Solar Three ) Project
Quote:
• A larger thermal storage system (15 hours, 647 MWh, 6250 t salts) with
insolated tank immersion heaters.
This high-capacity liquid nitrate-salt storage system is efficient and low-risk, and high-temperature liquid salt at 565ºC in stationary storage drops only 1-2ºC/day.
The cold salt is stored at 45ºC above its melting point (240ºC), providing a substantial margin for design.
http://www.sener.es/EPORTAL_DOCS/GEN.../SOLARTRES.pdf
Conservatively 2ºC / 565ºC per day = .0035 being .35% heat loss per day, which when annualised might effectively approach 99% heat retention per year, based on the fact that the daily heat store is emptied and recharged each day. i.e. the system does not allow for the opportunity for more than say 1% heat loss per day, as the heat energy stored is typically used within 24 hours to generate electricity. Bearing in mind also that electricity generation via steam turbines, is a seperate process to storage, in terms of measuring process efficiency. I understand this
SOLARTRES design surpasses the "Solar Two" project design in terms of performance and size.
Solar Power Tower report - suggests 99% storage efficiency - data table 2
http://www.solarpaces.org/CSP_Techno...olar_tower.pdf
OVERVIEW OF RECENT RESULTS OF THE SOLAR TWO TEST AND EVALUATIONS ...
http://www.osti.gov/bridge/servlets/...wable/3256.pdf
Solar two Performance Evaluation as a whole;
http://www.nrel.gov/docs/fy99osti/26642.pdf
Wiki's remarks
Quote:
The Solar Two used this method of energy storage, allowing it to store 1.44 TJ (400,000 kWh) in its 68 m³ storage tank with an annual storage efficiency of about 99 percent.[87]
http://en.wikipedia.org/wiki/Solar_energy
http://en.wikipedia.org/wiki/Solar_Two
http://www.metaefficient.com/renewab...lten-salt.html
STORAGE OF THERMAL ENERGY - UNESCO - EOLSS
http://www.eolss.net/ebooks/Sample%2...3-14-02-00.pdf
ROUND TRIP EFFICIENCY - terms used
http://en.wikipedia.org/wiki/Grid_energy_storage
http://www1.eere.energy.gov/solar/pdfs/kolb.pdf
http://www.greenhouse.gov.au/renewab...est-review.pdf
http://www.eurec.be/component/option...d,4/Itemid,43/
MISC
WIKI
http://en.wikipedia.org/wiki/Solar_Two
2000 Parabolic Trough Technology Workshop
http://www.nrel.gov/csp/troughnet/wk...0.html#storage
ANU Solar Thermal Energy Research
http://engnet.anu.edu.au/DEresearch/...ors/basics.php
http://www.solarpaces.org/Library/do...German_BMU.pdf
Ultracapacitors Minutes Charging 
Linear Mode
