Solar energy may help pry hard-to-recover 'heavy oil' out of old fields
In central California's sun-baked Kern County, solar power may soon be steaming oil right out of the ground. The Department of Energy (DOE) and to least two oil companies are developing plans for using solar energy in two small oil fields near hot and dusty Bakersfield, 100 miles north of Los Angeles.
Under a DOE project begun last April, Exxon Enterprises (Exxon USA's solar company) and Petro-Lewis, a small, Denver-based oil company, have begun exploring ways to use solar energy to extract hard-to-pump, molasses-thick heavy crude that lies layered in sand beneath Kern County. The oil -- which is heavier and much more difficult to extract than light crude -- already is pumped out of the area at the rate of 200,000 barrels of oil a day, using what are known as secondary and tertiary recovery methods.
But the price is stiff: For every two barrels of oil that are recovered, a third barrel must be burned in a boiler to create steam. The steam is injected underground to force out the slow-moving crude.
The high price of steaming out heavy crude can be lowered substantially with sun power, agree federal energy officials, oil company researchers, and private consultants.
Currently 300,000 barrels of heavy crude -- one-third of California's daily oil production -- are steamed each day from the state's heavy crude reservoirs, which are estimated to hold as much as 50 billion barrels of oil (only 25 percent of which is thought to be recoverable). An additional 150,000 barrels of heavy crude pumped daily is essentially lost because it must be burned to create more steam.
It is here that solar energy -- and the first-ever projects being considered by Petro-Lewis and Exxon -- could help.
Potentially, says Jim Dollare, a DOE official involved with the solar-enhanced oil recovery program, all the oil now burned could be saved and production upped slightly if solar power were to replace the fossil fuel boilers currently used in steam recovery.
But to save that oil, he says, would take $25 billion to build 1 billion square feet of solar collectors.
And before that will ever happen, a number of major kinks must be ironed out of what is still a fledgling technology. The roadblocks include bringing down the high cost of solar systems, developing more efficient equipment, and proving to reluctant oil companies that solar can do the job.
Those problems are expected to be addressed -- in a small way -- by the Exxon and Petro-Lewis demonstration projects, which have gone from the preliminary evaluation stage to actual proposals awaiting approval.
Although the Exxon project was initiated and partially funded by DOE, Exxon officials told DOE recently that they are sufficiently interested in the project to go ahead on their own, without government funding. The program must first receive final approval from Exxon's board of directors -- a decision that is to be made within the next month.
Under the Exxon plan, solar power will be introduced gradually on the Bakersfield site. Rather than replacing the two boilers now used there, solar energy will be used to preheat water to about 250 degrees. Pumped into fossil-fuel boilers, which will double the temperature, the steam will be injected into the heavy crude reservoirs deep underground.
Even such a small-scale use will result in savings of approximately 5,000 barrels of oil yearly -- a little more than 10 percent of the 40,000 barrels of oil burned in one boiler each year, according to Jeffrey Hamilton, vice-president of solar-thermal systems for Exxon Enterprises.
The proposed system will cost between $5 million and 10 million, Mr. Hamilton says. It will be a 100,000-square-foot parabolic trough -- essentially a long line of solar collectors which will heat water passing through it.
The Petro-Lewis plan, which was proposed and designed by General Atomics, a San Diego-based company that builds nuclear power reactors, skips over the preheating process.
It would be used to create steam directly, although it would only lessen, not replace, fuel burned in the three boilers now used on the field. Depending on the size of the collector built, General Atomics estimates that up to 12,300 barrels of oil could be saved yearly.
Unlike Exxon, however, Petro-Lewis cannot take on the project alone. It has asked DOE to share under 50 percent of the system's cost, a proposal now being evaluated by DOE.
Although solar power may never entirely replace fossil-fuel boilers, they say it will cut down on oil consumption as well as ease air pollution caused by fossil-fuel burning.