Plant size can impact the specific power consumption of SWRO systems. This has always been the case, however with the newer isobaric energy recovery technologies plant sizes from 20,000-130,000 gpd (100-500 m3/day) can be as efficient as the largest plants. At 65,000 gpd (245 m3/day) the ADC pilot system demonstrates equivalent overall efficiency compared to the largest trains, but the ADC system tends to be slightly more efficient than mid range trains sizes from 264,000 gpd to 2.6 mgd (1000-10,000 m3/day). However, with the introduction of the new "Pressure Center" designs these mid-range plant sizes will also become more efficient and comparable to the ADC system.

The pressure center design employs very few numbers (typically 1-3 units) of very large main HP pumps to feed numerous RO trains in parallel. Compared to traditional train-by-train design, this approach uses approximately ¼ as many main HP pumps that are approximately 4 times larger in size. The larger pumps are more efficient and thereby save energy. The 88 mgd Ashkelon plant in Israel is the first plant in the world to use the pressure center design. Dr. Boris Liberman wrote a paper on his unique plant design that can be viewed by clicking here.

This financial analysis took a conceptual look at the 20 year life cycle for a 50 mgd SWRO plant and included overall treatment costs such as intake and distribution power, chemicals, maintenance, replacement, labor, capital costs and interest on capital. The analysis did not include land, depreciation, distribution improvements or intake capital costs and it assumes co-location with an existing power plant or other existing intake system.

No. Our NPV model includes pretreatment and post treatment costs.

Our analyses used a conservative $700/membrane.

For the first set of membranes (SW30HR-380), our most affordable recovery and flux point was 50% recovery at 6 gfd and resulted in projected treatment costs of $2.47/kgal ($0.65/m3). The NPV analysis says that these are the least expensive conditions to operate at, but the analysis only looked at a "snap shot" of site specific pilot operating data. Experienced operators and plant designers may prefer to design around different conditions. More typically a California SWRO plant might be designed at 45% recovery and 7.5 gfd, which would result in treatment costs of approximately $2.55/kgal ($0.67/m3) and provide improved performance in terms of better water quality and lower fouling potential.

For the SW30HR-380 test, the permeate water quality averaged 180 TDS with 0.8 mg/L of boron.

For the SW30HR-380 membranes, the RO feed pressure averaged around 840 psi.

Raw seawater was taken from an open intake from the Pacific Ocean. Pre-filtration included single stage sand filtration followed by 5 micron cartridge filtration.

The energy required to produce fresh water from seawater or brackish water is defined by the specific power consumption of the desalination system, i.e., the power per unit of time required to produce a unit of water. Our energy number for the RO process includes the main HP pump power and pressure exchanger booster pump power divided by the permeate flow rate. We do not include the power required for seawater supply, pretreatment, post treatment and distribution. We have chosen to isolate the RO process for the following reasons:

1. On average, the RO process power represent around 70% of the total power required to treat and distribute water in a seawater desalination plant.

2. The RO process is the least understood and most over estimated energy number in the total treatment process as demonstrated by the fact that we are producing numbers 35-40% below what many experts have estimated to be possible.

3. The pre-treatment and post treatment energy requirements will very from site to site in California, but the energy required for the RO process will be relatively similar assuming that the process and applied technologies are similar..

The NPV model used estimated allowances for the total treatment power including raw seawater intake pumps (200 ft-head), pre-filtration pumps (105 ft-head), the actual RO process number from the ADC pilot, product water lift pumps (40 ft-head) and product water finish pumps (200 ft-head). For the first set of SW30HR-380 membranes, the total treatment power from our NPV model at the MAP was 10.67 kWh/kgal (2.82 kWh/m3) verses 7.15 kWh/kgal (1.89 kWh/m3) for the RO process alone.

Yes. All of the equipment used in the ADC system is commercially available "off the shelf." Every piece of technology and the process we are demonstrating have been proven and applied in full scale systems around the world and can be applied to California systems.

The energy required to produce fresh water from seawater or brackish water is defined by the specific power consumption of the desalination system, i.e., the power per unit of time required to produce a unit of water.
Typical specific power consumption for the most common, commercially proven desalination processes and other traditional sources of water are:

Thermal Processes seawater:

At the energy levels demonstrated by the ADC it takes approximately 120 Watts to produce 400 gallons of water per day. This is enough water for an average home in California per day. The table below shows some other typical appliances that might be operating in a California home with comparable energy consumptions.

The discharge outfalls are designed to facilitate rapid dispersion of the brine stream into the local ocean. Engineering considerations include water depth, local currents, physical structure of the water column, and wave climates. In most cases, the brine is quickly dispersed and does not have a significant impact on the local marine environment.