BLUE ENERGY

[ RESEARCH DOCUMENT -- Rajiv Gandhi University of Knowledge Technologies ]

INTRODUCTION :

Electricity is very much essential for our day to day life . The current energy production is largely based on fossil fuelsand is not only characterized by vulnerability and imminent scarcity but also by emission of greenhouse gases as aconsequence of combustion of fuels. We are going to introduce blue energy concept which means to extract electricity from the difference in salt concentration by using modern scientific techniques.The globally available power in the form of salinity gradients has been estimated in 1970’s to be between 1.4 and 2.6TW, which is approximately 20% of the world wide energy demand and more than the global electricity consumption(2.0 TW).

BLUE ENERGY :

Salinity gradient energy is based on using the resources of “osmotic pressure difference between fresh water andsea water”. When a drop of salt water falls into a lake of fresh water, there is a “spontaneous” net motion of ions in the water The reason why ions move in the entropy of the mixed system is larger , and hence the free energy is lower. This energy is called “BLUE ENERGY” which is non polluting sustainable technology to generate energy by mixing water stream with different salinity.

WORKING PRINCIPLE:

Basically it uses the Gibbs energy (which is the maximum amount of non-expansion work that can be extracted from a Thermodynamically closed system (one that can exchange heat and work with its surroundings, but not matter). This maximum can be attained only in a completely reversible process. When a system transforms reversiblyfrom an initial state to a final state, the decrease in Gibbs free energy equals the work done by the system to its surroundings, minus the work of the pressure forces.) of mixing of salt solutions with different concentration to generate electrical energy. In order to obtain energy from the salt water, two solutions of solutions of different concentration must be available . The energy that can be extracted from the two solutions is directly proportional to the absolute temperature.By mixing 1 m^3 fresh water per second with an excess of sea water , considered as a salt solution with a salt concentration of c=0.5 molar , the maximum recoverable dissolution energy is 2.35 MW.[ ??? = ??? ? ?????] equation for Gibbs energy3

METHODS FOR TAPPING BLUE ENERGY:

Basically there are 4 methods :

1. PRESSURE RETARDED OSMOSIS

2. REVERSE ELECTRO-DIALYSIS

3. CAPACITIVE METHOD

4. VAPOUR PRESSURE DIFFERENCE METHOD

PROjECT INFO:

In our project we are going to create 8 chambers each chamber contains 2 portions separated with a semi-permeable layer of which 5 chambers are first level and 3 are second level.First level starts from taking 1kiloliter of fresh water and 1kiloliter of saltwater and when the two solutions get equilibrium state of volume, then the flow of fresh water into salt water starts and 24% of it get flowed into salt water due to atmospheric pressure which is about 760mm and the process happened is osmosis.Then the fresh water remains 760lts and salt water get diluted up to 24% and remains 1240lts so then for next chamber by adding that 760lts from first chamber and also extra 240lts to make 1kl .And from 1240lts saltwater taking 1000lts to second chamber leaving 240lts a side .similarly continues up to next 3 chambers from second chamber resulting in complete 2kiloliter of pure RO fresh water ,and 960lts of 40%concentrated salt water .By this first level completed resulting generation of about 7.3MW of electricity, 960lts of 40%concentrated saltwater .Now in second level this 960lts will be furtherly used to generate electricity .As in first level same setup will be arranged ,here 3 chambers are there from first chamber 40% concentrated saltwater will convert into 16% saltwater and this will be passed to 2 nd chamber here this 16% will be completely turned into 2kiloliters of fresh water leaving 45.6lts of salt resulting in generation of 1.316MW of electricity .So totally by using 1960lts of fresh water and 1040lts of salt water we can generate 8.616MW of electricity leaving 2713.5lts of fresh water and 45.lts of salt. From our analysis we can say that 286.5lts of salt water can produce 8.616MW of energy, since out of taking total 3kl of fresh and salt waters , fresh water get increased resulting in decrease of salt water and we totally get 2713.5lts of fresh water so 286.5lts of salt water is get converted into salt and energy .And thiswhole process will take feasible time and place or area , and the membrane for one chamber will also require 1m^2 area that’s enough for the required process.

"THIS IS A CLEAN ENERGY, NON POLLUTING THE ENVIRONMENT."

CONCLUSION:

“Blue Energy is the promising renewable energy source for the future. Over 80% of the current global electricity demand can be met through ‘BLUE-ENERGY’ Technology .This translates into reduction of approximately 40% of global energy related greenhouse gas emissions ;however , significant efforts are still required to make salinity gradient energy competitive as compared to other renewable energy resources .Young scientists are still working on to develop the semi-permeable membrane of low cost and non-polluting one , so that can be easily decomposed .

REFERENCES:

1] Briefing Paper about Blue Energy Keesvan denEnde & Frederik Groeman KEMA Consulting October 2007

[2] O. Davidson, B.metz,Special report on carbon dioxide capture and storage. Climate Change “Recent developments in salinity gradient power”. Oceans. 2003.2284-2287.)

[3] John Gartner (2009-11-24). "World's First Osmotic Power Plant Opens"

[4](Jones,A.T.,W. Finley.“Recent developments in salinity gradient power”. Oceans. 2003. 2284-2287.)

[5] Norman, R.S., Water salination: A source of energy,Science 4161 (1974).

[6] Osmotic power - Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/Osmotic_power)

Thank you very much,

A student from RGUKT Nuzvid.