A Feasibility Study - Aaltodoc - Aalto-yliopisto

All the calculations are for one WaveRoller unit with a width of 30 m.
The product water must have a TDS value lower than 500 mg/l, as recommend
by the United States Environmental Protection Agency (EPA 2012).
The DOW FILMTEC SW30HRLE-370/34i by the Dow Chemical
Company is chosen as the reverse osmosis membrane, due to its capabilities in
performing well with challenging feed waters.
The reverse osmosis pressure vessels will be for seven membrane elements each
Each Site will be examined in a study area, comprising of a range on
WaveRoller nominal pump capacities, starting from 0,03 m³/s and ending with
0,24 m³/s.
For each location the change in elevation from the WEC to the shore is 15
m, the distance travelled to the shore is 500 m and each pipeline has one inlet
and outlet and four 90º corners.
The pressure loss from the travelled distance from the WEC to the shore will be
kept under 3 bar, but since it is small compared to the initial pressure, it will be
disregarded in the actual calculations in order to simplify the calculations.
Financial calculations will be performed using the annuity method, with an
estimated lifetime of 25 years and an interest rate of 8 %.
The operational expenses are calculated with a fixed percentage share of the
capital expenses: 5 % for the WEC and 15 % for the RO.
In ROSA, the harshest option for the pre-treated water is chosen (Seawater with
conventional pre-treatment, SDI < 5).
The Energy Recovery Device (ERD) will be a hydraulic turbocharger with a
computational average efficiency of 65 % (FEDCO 2012).
From each site the permeate production (m³/day), the load factor (suitable wave
power / available wave power), the cost of water (€/m³), the recovery rate, the
permeate TDS (mg/l) and cost details will be given.
54