* Pacific Ethanol seeks protection for its plants

* Pacific Ethanol lined up $20 mln in bankruptcy finance

* TXCO Resources squeezed by falling energy prices

* TXCO seeks approval for $32 mln to fund bankruptcy
(Adds Pacific Ethanol results, paragraph 9)

By Tom Hals

NEW YORK, May 18 (Reuters) - Tumbling energy prices over the
past year and a lack of credit pushed two U.S. energy companies
into Chapter 11 bankruptcy, the latest in a string of such
filings.

Pacific Ethanol Inc (PEIX.O: Quote, Profile, Research), the largest West Coast-based
producer and marketer of ethanol, put its production plants in
California, Oregon and Idaho in Chapter 11 bankruptcy, the
company said on Monday. The company's marketing arm, which buys
and sells ethanol, did not file for bankruptcy.

Oil and gas exploration company TXCO Resources Inc TXCO.O
said it also filed for Chapter 11 bankruptcy, along with seven
subsidiaries.

Energy companies have suffered as the economic downturn sent
prices for natural gas, crude oil and gasoline down sharply from
their peaks in July, squeezing many of the smaller players.

Norwegian oilfield driller PetroMENA (PMENA.OL: Quote, Profile, Research) filed for
bankruptcy on Sunday in the United States and exploration
company Energy Partners Ltd (ERPLQ.PK: Quote, Profile, Research) of New Orleans filed for
bankruptcy on May 1.

Pacific Ethanol, which reported 2008 revenue of $703.9
million, said it plans to continue marketing and selling ethanol
under existing marketing agreements.

The five bankrupt subsidiaries have obtained bankruptcy
financing of up to $20 million, which will allow them to
continue operating while they reorganize, the company said.

The company said on May 12 it would likely need to file for
bankruptcy if it was not able to restructure its debt.

Later on Monday, Pacific Ethanol reported a first-quarter
loss of $23.9 million on revenue of $86.7 million, with the
revenue down by nearly half from the year before.

Makers of the corn-based biofuel have struggled as weak U.S.
demand for motor fuels has depressed prices and margins, and
last year VeraSun Energy VSUQE.OB, once the largest publicly
listed U.S. ethanol maker, filed for bankruptcy.

Pacific Ethanol, based in Sacramento, California, had said
that the volume of ethanol sold fell 24 percent in the quarter,
while the average sales price was down 28 percent. It said in
court documents it had between $50 million and $100 million in
assets and between $100 million and $500 million in
liabilities.

TXCO Resources said in a court filing that it sharply
increased capital expenditures last year just as prices for its
oil and gas plummeted more than 50 percent, putting a severe
strain on the company's cash.

The San Antonio-based company said in court documents it had
$432 million in assets and $323 million in liabilities. It said
it would seek court approval for $32 million in financing to get
it through bankruptcy.

The company had 2008 operating revenue of $143.7 million and
participated in 96 wells, mostly in Texas.

Shares of Pacific Ethanol and TXCO Resources were both down
more than 40 percent in morning trade.

The cases are In re: Pacific Ethanol Holding Co LLC, U.S.
Bankruptcy Court, Southern District of Texas, No. 09-11713 and
In re: TXCO Resources Inc, U.S. Bankruptcy Court, Western
District of Texas, No. 09-51807.
(Reporting by Thomas Hals, with additional reporting by Braden
Reddall in San Francisco; editing by Dave Zimmerman and Matthew
Lewis)