I estimate the pumping energy load to be about 2.5% of the solar load. What this means is that for every Kw that we use of solar energy to produce transpiration/condensation - thus harvesting fresh water - we use 25 watts of electrical power to pump cooling water to chill the roof and cold seawater to reject the thermal gain. Therefore there is 2000 Kw per year of solar energy per square meter that we use and also 50 Kw of electrical power, which I will cost at 0.05 USD per Kw = $2.5 per M2 per year. This is still a fair and conservative estimate of the energy "cost" of producing from one square meter 10 L water per day or 3650 L or about 3.6 tons of water per year. Thus the cost is $0.68 per ton, while conventional is distillation costs (all in - capital + energy + operating maintenance) $2 a ton. So, since the oil production from algae cultivation can pay for our buildings many times over - and cover the electrical power consumption that is spent to run the system. Remember that the pumping of the cooling water to the roof is a necessary cost of growing the algae. Therefore it could be charged to the cost of condensing the transpired moisture within the building (and providing a controlled environment for the plant biomass crop production) or it could be charged as a cost of the algae production system.
The other interesting aspect is that the Eco Sphere and other Sola Roof structures? are not hot within (as are most solar distillation enclosures) but are climate controlled and comfortable space. The entire surface area of the floatation rafts or "aquatic plant pool" within the structure is filled with plants and we do not what to block any of the sunlight to reach the plants because the shade that is produced will decrease the transpiration and water production. But still people could go into the space and it could be used for tourism or recreation in some way (perhaps). Additionally some birds for eggs or meat (for example some ducks are as productive as chickens for eggs and at 18 to 24 months they can be harvested for meat) or fish culture could be cultivated together with the seawater hyacinth. Other seawater loving crops can be grown and some of these are possible food crops.
Another advantage is that all or a portion of the crop production pool can be separated from the seawater and used to grow fresh water crops at low production cost and generate a high profit. We can use the "flotation raft" growing system to grow all kinds of fresh produce. For example we can grow 500 heads of lettuce per M2 per year - that would produce an income of $200/M2/yr. In the past the region has looked for sustainable growing systems and tried greenhouse systems but they have been a failure and the crop production uses too much water in standard greenhouses or in field culture. However in our solar production domes all of the fresh water consumed by the plants is recovered - so although the fresh water crops will not produce water from seawater, neither will their production consume any fresh water. This is a significant outcome and we can produce on land along the coast as well as on sea since the cold seawater is just as accessible.
Please let me know what your thoughts are on this - I would like to know that you understand the proposal as fully as possible. Clearly some of the details must be proven out by actual project results. But the fundamental parameters are quite reliable and are based on known phytomechanisms and know engineering design for pumping water. I would appreciate where you can confirm some of the statements that I make or if you can fill in any gaps.