He then retired to private life as the CEO of energy services company Haliburton for five years, but he felt a new calling when then-Texas Gov. George W. Bush asked him to lead his search for a vice presidential candidate.

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Nest Energy Services is the company's attempt at a DRM-free conservation system.

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The company was the official Temporary Energy Services Supplier to the London 2012 Olympic and Paralympic Games.

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The enthusiasm for energy stocks spilled over into a niche oilfield services company: Amsterdam-based Core Laboratories NV, which provides drillers with production development and reservoir management products and services.

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Direct Energy Chief Executive Chris Weston needed a new home for his company, which provides electricity, natural gas and home energy services to 6 million residential and business customers across North America.

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The company's businesses include services for engineering, construction, technology, chemicals and energy industries.

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Mr Cheney also used to run Halliburton, an energy company that won lucrative reconstruction contracts in Iraq and now stands accused of overcharging the Pentagon for some services.

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