Cloud Peak Energy Successful Bidder for West Antelope II North Coal Tract

Cloud Peak Energy Inc. (NYSE:CLD), the third-largest U.S. coal
producer and the only pure-play Powder River Basin (PRB) coal company,
today announced its successful bid for the West Antelope II North Coal
Tract, which was previously nominated by the company′s Antelope mine.
The Bureau of Land Management (BLM) estimates this tract contains
approximately 350 million tons of mineable coal. At year-end 2010, the
company′s Antelope mine had an estimated 252 million tons of coal
reserves, and Cloud Peak Energy had an estimated total reserve of 970
million tons of coal.

Cloud Peak Energy successfully won the lease sale with a bid of
approximately $297.7 million, or approximately $0.85 per ton, based on
the BLM′s estimate of 350 million mineable tons. The company submitted a
payment for approximately $59.5 million, which is the first of five
equal payments for the federal coal lease. The BLM typically awards the
lease within several months after selecting a winning bidder. As
previously disclosed, the West Antelope II Lease by Application (LBA) is
subject to pending legal challenges filed by certain environmental
organizations against the BLM and the Secretary of the Interior.

The issuance of the coal lease for this tract will facilitate access to
an additional 80 million tons of non-reserve coal deposits controlled by
the Antelope mine. This additional coal is controlled through a lease
with the State of Wyoming.

'We′re very pleased with our acquisition of the West Antelope II North
Coal Tract. This tract is expected to more than double the reserves at
the Antelope mine and, along with the additional coal within the State
of Wyoming lease, add about twelve years of production,? said Colin
Marshall, President and Chief Executive Officer.

The BLM also recently announced a June 15, 2011 sale date for the West
Antelope II South Coal Tract, which contains approximately 56 million
mineable tons, according to BLM estimates.

About Cloud Peak Energy ®

Cloud Peak Energy Inc. (NYSE:CLD) is headquartered in Wyoming and
is the third largest U.S. coal producer and the only pure-play Powder
River Basin (PRB) coal company. As one of the safest coal producers in
the nation, Cloud Peak Energy specializes in the production of low
sulfur, subbituminous coal. The company owns and operates three surface
coal mines in the PRB, the lowest cost major coal producing region in
the nation. The Antelope and Cordero Rojo mines are located in Wyoming
and the Spring Creek mine is located near Decker, Montana. With
approximately 1,500 employees, the company is widely recognized for its
exemplary performance in its safety and environmental programs. Cloud
Peak Energy is a sustainable fuel supplier for approximately 4 percent
of the nation′s electricity.

Cautionary Note Regarding Forward-Looking Statements

This release contains 'forward-looking statements' within the meaning of
the safe harbor provisions of Section 27A of the Securities Act of 1933
and Section 21E of the Securities Exchange Act of 1934. Forward-looking
statements are not statements of historical facts and often contain
words such as 'may,' 'will,' 'expect,' 'believe,' 'anticipate,' 'plan,'
'estimate,' 'seek,' 'could,' 'should,' 'intend,' 'potential,' or words
of similar meaning. Forward-looking statements are based on management's
current expectations or beliefs, as well as assumptions and estimates
regarding our company, industry, economic conditions, government
regulations and energy policies and other factors. Forward-looking
statements may include, for example, (1) our estimates of proven and
probable coal reserves, future production and reserve life, (2) BLM′s
timing to award the coal lease for the West Antelope II North LBA and
the timing of future LBAs, (3) our ability to obtain all required
regulatory permits and approvals to mine newly acquired coal tons in a
timely and cost-effective manner, (4) the impact of pending or future
third party litigation and regulatory challenges, (5) business
development and growth initiatives; and (6) other statements regarding
our plans, strategies, prospects and expectations concerning our
business, operating results, financial condition and other matters that
do not relate strictly to historical facts. These statements are subject
to significant risks, uncertainties, and assumptions that are difficult
to predict and could cause actual results to differ materially from
those expressed or implied in the forward-looking statements. For a
discussion of some of the factors that could adversely affect our future
results, refer to the risk factors described from time to time in the
reports and registration statements we file with the Securities and
Exchange Commission ('SEC'), including those in Item 1A - Risk Factors
in our most recent Form 10-K and any updates thereto in our Forms 10-Q
and current reports on Forms 8-K. There may be other risks and
uncertainties that are not currently known to us or that we currently
believe are not material. We make forward-looking statements based on
currently available information, and we assume no obligation to, and
expressly disclaim any obligation to, update or revise publicly any
forward-looking statements made in this release, whether as a result of
new information, future events or otherwise, except as required by law.

Cloud Peak Energy Inc.

Karla Kimrey, 720-566-2900

Vice
President, Investor Relations