TransAlta extends offer for Canadian Hydro Developers, Inc. until September 11, 2009

CALGARY, ALBERTA, Aug 27 (MARKET WIRE) --
TransAlta Corporation (TSX: TA) (NYSE: TAC) announced today that its
wholly-owned subsidiary has extended its offer (the "Offer") to acquire
all of the issued and outstanding common shares of Canadian Hydro
Developers, Inc. (TSX: KHD) for $4.55 per share in cash. The
fully-financed Offer will now remain open until 6:00 p.m. (Calgary time)
on September 11, 2009, unless withdrawn or extended.

TransAlta determined to extend the Offer following a decision on Tuesday,
August 25, 2009 by the Alberta Securities Commission (ASC) that its
intervention to cease trade Canadian Hydro Developers' shareholder rights
plan was not warranted at this time. In making its decision, the ASC
acknowledged the need for such intervention could change in the coming
weeks as circumstances warrant.

Aside from the extension, the terms and conditions of the Offer described
in the Offeror's offer and take-over bid circular dated July 22, 2009
remain unchanged. The Offer represents a premium of approximately 30 per
cent over the $3.50 volume weighted average trading price of the Canadian
Hydro Developers common shares over the 10 trading days immediately prior
to July 20, 2009, and approximately 25 per cent over the closing price on
July 17, 2009, the last trading day before TransAlta disclosed is
intention to make the Offer.

The Offeror will mail a formal notice of extension to Canadian Hydro
Developers shareholders as soon as practicable. The notice of extension
will also be available on the SEDAR website at www.sedar.com and at
www.transalta.com.

The transaction will be funded initially with new committed bank
facilities fully underwritten by Royal Bank of Canada, which, along with
existing credit facilities and internally generated cash, will provide
ample funding to take up and pay for all the outstanding Canadian Hydro
Developers shares. This initial funding will be replaced with permanent
long-term funding in the debt capital markets, underpinned by raising an
additional $250 - $300 million of equity. The transaction will not impact
TransAlta's dividend policy.

TransAlta strongly encourages shareholders of Canadian Hydro Developers
to read the offer and take-over bid circular mailed to all shareholders
of Canadian Hydro Developers on July 22, 2009, together with the notice
of extension. The offer and take-over bid circular, as amended by the
notice of extension, contain the full terms and conditions of the Offer
as well as detailed instructions on how shareholders can tender their
common shares to the Offer. Copies of the offer and circular and related
documents are available online at www.transalta.com.

Canadian Hydro Developers shareholders electing to tender their common
shares to the Offer must complete the letter of transmittal or, if
necessary, the notice of guaranteed delivery (both of which accompany the
offer and take-over bid circular) and return the appropriate document in
accordance with the terms and conditions more fully set out under
''Manner of Acceptance'' in Section 3 of the Offer. If common shares of
Canadian Hydro Developers are held in the name of a nominee, such as a
broker, investment dealer, bank or trust company, the shareowner should
contact such nominee for instructions on how to deposit their common
shares to the Offer.

For assistance in tendering common shares to the Offer, Canadian Hydro
Developers shareholders are encouraged to contact Georgeson Shareholder
Communications Canada Inc. at 1-866-783-6752 (North American Toll Free
Number) or 1-212-806-6859 (Bank, Brokers and collect calls).

TransAlta is a power generation and wholesale marketing company focused
on creating long-term shareholder value. We maintain a low to moderate
risk profile by operating a highly contracted portfolio of assets in
Canada, the United States, and Australia. Our focus is to efficiently
operate our coal-fired, gas-fired, hydro and renewable facilities in
order to provide our customers with a reliable, low-cost source of power.
For nearly 100 years, we've been a responsible operator and a proud
contributor to the communities where we work and live. TransAlta is
recognized for its leadership on sustainability by the Dow Jones
Sustainability North America Index, the FTSE4Good Index and the Jantzi
Social Index.

Reader Advisory

This news release may contain statements that constitute "forward-looking
information" or "forward-looking statements" (collectively
"forward-looking information") within the meaning of applicable
securities legislation. This forward-looking information is subject to
numerous risks and uncertainties, certain of which are beyond TransAlta's
control including, without limitation, uncertainty related to the
completion of the offer to acquire Canadian Hydro Developers and the
effects of the transaction in the event it is completed on TransAlta, the
impact of legislative or regulatory developments, competition, global
capital markets activity, changes in prevailing interest rates, currency
exchange rates, inflation levels and general economic conditions in
geographic areas where TransAlta operates. Readers are cautioned that the
foregoing list of risk factors is not exhaustive. Additional information
on these and other factors that could affect TransAlta's results are
included in reports on file with the Canadian and United States
securities regulatory authorities. TransAlta's actual results,
performance or achievements may differ materially from those expressed
in, or implied by this forward-looking information and, accordingly, no
assurance can be given that any events anticipated by the forward-looking
information will transpire or occur, or if any of them do so, what
benefits that TransAlta will derive therefrom. Forward-looking
information is based on the estimates and opinions of TransAlta's
management at the time the information is released and TransAlta does not
undertake any obligation to update publicly or to revise any of the
forward-looking statements, whether as a result of new information,
future events or otherwise, except as may be required by applicable
securities laws.

This news release does not constitute an offer to sell or the
solicitation of an offer to buy any securities. No offering of securities
will be made absent registration under, or an exemption from the
registration requirements of, applicable securities laws.

Note: All financial figures are in Canadian dollars unless noted
otherwise.

Contacts:
TransAlta Corporation - Media inquiries
Michael Lawrence
Manager, External Relations
Phone: (403) 267-7330
Email: michael_lawrence@transalta.com

TransAlta Corporation - Investor inquiries
Jennifer Pierce
Vice President, Communications & Investor Relations
Phone: (403) 267-7622 or 1-800-387-3598 in Canada and U.S
Email: jennifer_pierce@transalta.com

TransAlta Corporation - Investor inquiries
Jess Nieukerk
Manager, Investor Relations
Phone: (403) 267-3607
Email: jess_nieukerk@transalta.com
Website: www.transalta.com

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