Another Alternative Energy from the Ocean
Ocean Thermal Energy Conversion is what we are talking about here or (OTEC). It is a potential energy source of the future. However, at the present time the Natural Energy Laboratory of Hawaii is home to the only operating experimental OTEC plant in the world.
There are three kinds of OTEC.
Closed Cycle OTEC
Closed cycle OTEC uses a low-boiling point liquid such as propane to act as an intermediate fluid. The OTEC plant pumps warm sea water from the surface of the ocean into the reaction chamber and uses it to boil the intermediate fluid. This results in the intermediate fluid’s vapor pushing the turbine of the engine, which thus generates electricity. The vapor is then cooled down by using cold sea water from the oceans depth.
Open Cycle OTEC
Open cycle OTEC is not that different from closed cycling, except with the Open Cycle there is no intermediate fluid. It uses the sea water itself to drive the turbine engine. Again using warm sea water found on the surface of the ocean and then turning it into a low-pressure vapor under the constraint of a vacuum. Then by releasing the low-pressure vapor in a focused area it has the power to drive the turbine. Then after it has generated sufficient electricity the deep cold ocean’s waters are used to cool down the vapor and also create desalinated water for human consumption.
Hybrid Cycle OTEC
There is also a hybrid cycle OTEC that is really just a theory for the time being. The theory is to make maximum usage of the thermal energy of the ocean’s waters. Actually there are two sub-theories to the theory of Hybrid Cycling.
The first involves using a closed cycling to generate electricity. This electricity is in turn used to create the vacuum environment needed for open cycling.
The second idea is to integrate two open cycles such that twice the amount of desalinated water is created then with just one open cycle.
Some Additional Advantages of OTEC
- In addition to a closed cycle OTEC plant being used for producing electricity, it can be used for treating chemicals.
- Both open cycling and closed cycling OTEC plants, are also able to be utilized for pumping up cold deep sea water which can then be used for refrigeration and air conditioning.
- Furthermore, during the period when the sea water is moderated and made ready to go back into the sea, it can be used for mariculture (a specialized branch of aquaculture) and aquaculture projects such as fish farming.
There is clearly quite an array of products and services that we could derive from this alternative energy source.
OTEC is a potential alternative energy source that needs to be explored much more than it presently has been. And this exploration needs to be funded better in order to discover cost effective ways of utilizing it. The greatest hurdle to get over with OTEC implementation on a wide and practical level is cost. With the processes presently being used to drive OTEC it is difficult to get the costs down to a reasonable level. The advantage of Ocean Thermal Energy would be it is very clean burning and would not add pollutants into the air. However, with our current technologies, OTEC plants would disrupt and perhaps damage the local water environments.
A Biofuel That’s Really Taking Off
Last summer one of the big oil companies ExxonMobil announced it would invest 600 million into research on making an oil-like biofuel from algae. It’s their largest single investment in renewable energy to date.
Using algae for making biofuels is showing some real promise for several reasons.
- Algae is one of the most efficient plants on earth photo synthetically. That means it is very efficient at turning sun light into plant food in the form of carbohydrates, proteins, and oils. The more efficient a plant is at converting solar energy into this chemical energy, the better its potential is from a biofuel perspective.
- The biofuel that can be made from algae has a molecular structure similar to petroleum. This makes it easy to use in traditional motors and engines.
As companies assess a plants biofuel potential they are looking at
- Its scalability (can we produce it easily)
- Any technical challenges there might be at producing it. When looking at the technical challenges the real question is what are our abilities to address the challenges?
- How it rates as far as its environmental performance is concerned.
- And the ability to produce it economically.
Algae offers several advantages over other biofuel alternatives.
- Unlike sugarcane, corn, or soy, algae can be grown using land and water that would otherwise not be able to be productive.
- Algae actually consumes carbon dioxide which would reduce greenhouse gasses.
- Even more important, algae have a higher potential bio-oil yield per acre than other alternatives. It is believed it could easily yield 2000 gallons per acre per year verses 50 to 650 gallons for the other alternatives, soy, corn, and sugarcane.
- Algae is also a very productive plant. It can be grown in a couple of days. This is part of the reason for the higher yield. It also makes the process of testing different variables and their fuel making potential faster and easier. This is especially true when comparing it to other crops where the growing time is a season long.
When it does go forward it will certainly be considered as a jet fuel and in fact this is already happening.
Last January a flight demonstration with a two engine aircraft using sustainable biofuels was performed, the first by a US carrier. This was a joint effort and used an algae based biofuel for this demonstration flight.
The algae based biofuel blend performed as well as or better than traditional jet fuel. It also had a 1.1 percent increase in fuel efficiency over traditional jet fuel. The greenhouse gas emissions (carbon emissions) related to using a biofuel of this nature are estimated to be reduced by 60 to 80 percent, compared with traditional jet fuel.
This was the first sustainable biofuel demonstration flight by a commercial air carrier using a two engine aircraft and the first biofuel demonstration flight by a commercial carrier using fuel partially derived from algae. Not only that, but because of the way the fuel was made, no modifications were necessary to the aircraft or the engines.
There is still some uncertainty as to whether an algae-based biofuel will prove commercially viable and it is felt that they will need a window of five to ten years before they know for sure.
Algae, though, is showing real promise as a source for a biofuel energy alternative.