Mature oil fields such as Prudhoe Bay and Kuparuk on Alaska’s North Slope produce vast quantities of water along with oil. That water is pumped back into the oil reservoirs to continue to flush oil out of the reservoir rocks.
But heat in the water equates to vast quantities of energy. Could some of that energy be captured, before pumping the water back into the ground?
Bernie Karl, a passionate advocate for the use of renewable energy and owner of the Chena Hot Springs Resort in Alaska’s interior, thinks so. Karl has pioneered the use of low-temperature geothermal power in a 200-kilowatt electricity power plant at Chena and wants to try that same technology to generate electricity from produced water on the North Slope.
“In Prudhoe Bay they have 1.2 million barrels of produced water every day. … That water is at 150 degrees (F),” Karl told Petroleum News. “There’s no power being made off that — all that energy … is being wasted.”
$724,000 grantThe U.S. Department of Energy has backed Karl’s concept by awarding a $724,000 grant, matched by equal funds from Chena Power and United Technologies Corp., and with assistance from BP, to modify the low-temperature geothermal turbine system developed at Chena to use produced water from the Prudhoe Bay oil field.
Sen. Lisa Murkowski, R-Alaska, announced the federal grant on Oct. 15.
“This is an important project for Alaska. … Using the water that today is just a waste product of oil and gas production can save energy in fossil fuel production and could add clean electricity to our nation’s power grid. It is an important project for the nation and the state,” Murkowski said in an Oct. 15 press release. The senator has been seeking a variety of grant aid from the federal government to advance geothermal development, her office said.
The Chena Hot Springs power plant uses what is known as an organic rankine cycle — geothermal water at 165 degrees F evaporates a refrigerant that then drives a generator turbine. Success with this system at Chena has opened the door to power generation from relatively low temperature geothermal sources.
In the North Slope application, Chena Power wants to install a single 225-kilowatt turbine to prove the concept of generating electricity from produced water. If successful, the system could be expanded to supply a significant amount of power for the North Slope oil fields, Karl said.
“They can make 20 megawatts, if they so desire, but you have to prove the concept,” Karl said.
Use anywhereKarl also said that a successful demonstration of the technology on the North Slope would pave the way for use of the technology anywhere in the world that there are oil fields.
“There are 250,000 oil and gas wells in Texas alone. There are another 250,000 oil and gas wells that are closed and shut-in,” Karl said. “They can produce 10,000 megawatts within 24 months. They have 265 degree (F) water they’re wasting.”
And rankine cycle power generation units of the type used at Chena Hot Springs resort are available on request from United Technologies Corp., Karl said.
“You can call up and order one of these units and get it,” he said.
But can the units be scaled to, perhaps, a single oil well?
“In many oil wells there’s enough (water) out of one well,” Karl said. “… At 163 degrees (F) you need 550 gallons per minute.”
Oil companies view produced water as a nuisance, he said.
“I would like to turn that water into a positive for them and I believe we can do that,” Karl said.