OTEC research.
We hired an elite master’s Engineer (now a shareholder) to help study OTEC and heat exchange. With his help we were able to make detailed observations about the cost of an OTEC unit. The results were really exciting. We created an ‘OTEC calculator’ with all the most important variables including ammonia quantity and net power output. We are now able to create a detailed and accurate picture of the outputs and physical requirements of an OTEC unit of any size. We can even know the width of the heat exchanger for a given tube diameter and HX Duty, and how much energy will be lost pumping fluids, and the temperature of the wastewater in seconds.
Parasitic Pressure Drop.
As for water delivery, narrowing the delivery hose can massively increase the amount of energy taken by friction on the walls of the hose. On scales that are relevant to SWAC and OTEC, increasing the diameter of a hose by just 10 cm can significantly reduce the amount of energy lost to parasitic pumping.
Additional Waste heat and renewable heat.
We found that additional waste heat can be added to the system with additional heat exchanger surface and that this addition of extra heat can boost net power tremendously.
Because the warm surface water is abundant, most if not all the power required to fully vaporise the working fluid can be renewable. Additional waste heat must not do the bulk of the work required to vaporise the ammonia as that is already done, instead it raises the temperature and pressure of the ammonia, and this can increase the net power potential of the additional heat dramatically.
A new start for failed and controversial technology?
The improvement in efficiency can mean that failed or controversial sources of power such as natural gas, biomass and solar-hot-water can be much more cost effective and therefore viable because they do not need to account for ‘the bulk’ of the phase change.
There might be no better way to use dirty fuels for heat and power because this is such an efficient process. The extra heat and pressure mean that OTEC can certainly work cost effectively in many more locations.
Sites outside the Tropics are viable for OTEC power generation all year round; this approach may produce some of the cheapest and most sustainable energy in the world. A supply of cold water is still required but this source of cold water is abundant and close to shore off the coasts of many countries including the USA and Europe.
Use of waste heat means never seen efficiencies and lower initial capital costs.
In being more productive per kg of water delivered, the diameter of the hoses and the quantity of water required can drop per net kw output; this can of course mean lower start-up capital costs, albeit with at least one source of additional heat.
Use of multi, low-, and higher-grade heat sources and system carbon status.
Depending on the arrangement of the hx more than one heat source can be used.
Apologies! – (26-06-2024)
Apologies for previous versions of this page, it does seem to have caused a misunderstanding, and it was feared as much that it would, then again, it was for the very most part correct. Yet again the software that was produced has shown its worth tremendously. The software shows a liquid vaporising at a higher temperature and pressure, the latent heat per kg dropping with increasing heat. It also shows (the equivalent of) a kw for kw change in evaporator duty post ‘latent heat’ duty and interestingly a decrease in the condensing heat rejection / heat exchanger duty as well as more gross / net power. Hence last year’s excitement.
It was assumed that ‘hydraulic-ing’ would allow for gas to be heated ‘ahead of’ / post a vaporising liquid/gas evaporator and indeed it may do, however fear has gotten the better of us, or at least we know an apology could be offered. Nevertheless, we have since found several ways to add extra heat that don’t have this problem, and these ideas are now inventions within a patent application. Unfortunately, we can therefore apologise no further. After a year and a half of research it now looks as though NEW-OTEC could serve industry like no other and that it may well have an exciting future.
Hydrogen compression and storage.
An OTEC powered turbo-compressor could avoid using electricity to compress hydrogen or any other gas. Cold water could be used to cool any compressed gas.
Materials and relative Costs.
Heat exchangers can be mass produced already and are an established art. Heat exchangers are readily transportable in conventional shipping containers.
Up to and over one thousand times less space is required compared with solar pv farms; heat exchangers are much less susceptible to damage from natural disasters.
Different materials can offer different advantages and micro-coatings can improve heat exchanger service life and lower costs. However, the rising cost of energy and the growing desire for sustainable energy security means that the basic cost of OTEC heat exchangers system are not an eye watering expense not even when compared with mainland energy prices.
Co2 Sequestration.
One of the most interesting aspects of deep-sea-cold-water technology is the potential to offset Co2.
Just one litre per second of cold water released for one year can have the same effect as one tree for one hundred years. Sites that can use deep-sea-cold-water can become sites for offsetting Co2. This has the potential to generate income and reduce the running costs for the user.
Deep-sea-cold-water, sea farming and biomass.
For the sea to be able to support large scale biomass projects, raising deep-sea-cold-water for the sake of bringing nutrients to the sea-surface is probably essential. The sea cannot otherwise support the growth of such a large stock. The nutrients can also be expected to help de-stress fish stocks by increase the volume of fertile sea-space and by making offshore sea-farming a real possibility.
