Osmotic Power Research Institute

Developing Renewable Energy from Osmosis

Humboldt State University and the Humboldt Bay Harbor District are teaming to develop the Osmotic Power Research Institute to study and bring to market renewable energy generation from osmosis.

This proposed project provides benefits to our local commu-nity and the nation by:

• creating a research center to study generation of renewable energy through pressure retarded osmosis

• redeveloping and reusing existing infrastructure at a former pulp mill site in Eureka, CA

• providing employment for the local community• encouraging collaboration between researchers• furthering development of a renewable energy source

for California and the nation

The research institute will be unique. Other federal National Marine Renewable Energy Centers (in Oregon, Hawaii, and Florida) focus on wave, tidal, ocean current, and ocean thermal energy; research to develop osmotic power is currently not being conducted at these centers.

Background

Seawater

EvaporationPower

HydroTurbine

Condensation

Precipitation

PRO Freshwater

Because of the exciting potential of PRO power technology to provide large amounts of renewable energy, pressure retarded osmosis is an area of active and promising research. Among the researchers pioneering this effort is Dr. Andrea Achilli, a faculty member in Humboldt State University’s (HSU) Environmental Resources Engineering Department and a Faculty Associate at the Schatz Energy Research Center (SERC). Dr. Achilli and colleagues at universities across the U.S., including Yale, Connecticut, Nevada, and the Colo-rado School of Mines, have demonstrated the validity of the PRO power concept in bench scale tests. There is need to continue to refine this technology, to work with membrane manufacturers to develop more efficient membranes, and to extend the work to pilot and demonstration scale facilities.

HSU and the Humboldt Bay Harbor District are teaming to develop the Osmotic Power Research Institute at the site of a former pulp mill near Eureka, California. The mill site is positioned on the Samoa spit between Humboldt Bay and the Pacific Ocean and is provided with up to 30 million gallons per day of fresh water by the Humboldt Bay Municipal Water District. The confluence of large quantities of fresh water, access to seawater, and industrial connections to the electric and natural gas grids make this site ideal for the institute.

The Osmotic Power Research Institute will provide local and national researchers with a central location to pilot their

Humboldt County — Ideal for PRO Research

The proposed site of the Osmotic Power Research Institute on the shore of Humboldt Bay in northern California

Osmotic Power Research InsituteOPRI

There is a natural tendency of salt solutions to be diluted by fresh water. This natural force appears as osmotic pressure.Osmotic pressure is a form of solar energy. The sun heats the ocean; water evaporates and falls as rain. When a river enters the sea, the osmotic pressure that develops between the river’s fresh water and seawater is large—about 330 pounds per square inch (psi) or the pressure of a water column approximately 760 feet high. We can capture this solar energy by using pressure retarded osmosis (PRO) tech-nology.

A PRO power system allows fresh water to permeate through an osmotic membrane into pressurized brine. The pressur-ized brine solution is passed through a turbine/generator to produce electric power. Treated wastewater can also be paired with seawater to generate power; this has potential for the many wastewater treatment plant outfalls along our coast.

PRO Power and Desalination — A Powerful SynergyAn intriguing potential use of PRO technology, which Dr. Achilli is currently investigating, is the pairing of PRO with desalination. Desalination — producing drinking water from seawater — is accomplished by reverse osmosis (RO). Seawater is forced through an osmotic membrane by pumping it to high pressure (~600 psi). Desalination is used for producing drinking water around the world, in areas such as southern California, the Middle East, Singapore, and Australia.

The energy for desalination has been substantially reduced in recent years by inclusion of pressure exchangers. A pres-sure exchanger recovers much of the pressure of the outlet brine and transfers the energy to the incoming seawater. The most efficient desalination plant in the world located in Ashkelon, Israel uses pressure exchangers to minimize the energy requirements. Still, desalination requires approxi-mately 5 to 7 times more energy than providing potable water from typical surface or groundwater sources.

A PRO power system can be combined with pressure recovery to further improve the overall energy efficiency of desalina-tion. The brine from a desalination plant is often blended with treated wastewater effluent before it is discharged to the ocean. The PRO system can extract energy from the osmotic pressure developed between the treated wastewater and the desalination brine. The addition of the PRO technology to the desalination process can further reduce the energy required for desalination by approximately 30 percent.

RO

PX

PRO

PX

Seawater

DrinkingWater

Treated Wastewater

Diluted Brine

Brine

Pump

PressureRecovery

ConventionalRO

The PRO system extracts power from the osmotic pressure devel-oped between the treated wastewater and the concentrated brine that results from desalination.

RO

PX

Seawater

DrinkingWater

Brine

Pump

PressureRecovery

Seawater is forced through an osmotic membrane by pumping it to high pressure (~600 psi).

Reverse Osmosis

Reverse Osmosis + Pressure Retarded Osmosis

Developing Renewable Energy from Osmosis

HSU, SERC, and the Humboldt Bay Harbor District are seeking local, state or federal support to further develop the proposed Osmotic Power Research Institute. The goal is to advance PRO technology and develop this important new source of renewable energy to benefit our community and the nation.

Support Is Needed to Develop this Renewable Resource

technologies; easy access to utilities, water, and data facili-ties; and shared research space to collaborate on projects. The institute will conduct research in the following areas:

•PROpowergenerationwithfreshwater. Study the use of freshwater and seawater for power generation, and the optimization of PRO membrane systems.

•PROpowergenerationwithwastewatereffluent. Study the use of wastewater effluent and seawater for power generation.

•PROpowergenerationwithindustrialbrineandwastewatereffluent. Study the use of wastewater effluent and industrial brines for power generation. This has potential where industrial brines are diluted for discharge.

•ReducingDesalinationEnergywithPRO. Study the use of PRO to generate power from desalination brine dilution, reduce the overall energy of desalina-tion for potable water supply, and reduce the envi-ronmental effects of discharging concentrated brine.

Office SpaceLaboratoriesTest Bays

Conceptual rendering of the proposed Osmotic Power Research Institute facility

Photo Credits• Photo of pulp mill and Humboldt Bay (on cover and on page 2) courtesy and © Gary Crabbe / Enlightened

Images; http://enlightphoto.com• Photo of ocean wave courtesy of Malene Thyssen, http://commons.wikimedia.org/wiki/User:Malene• Photo of child drinking courtesy of Ben Earwicker, Garrison Photography, http://www.garrisonphoto.org

OPRI

Humboldt BayHarbor, Recreation & Conservation District

Copyright © 2013 Schatz Energy Research Center