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LONDON -- An IT worker threw out a computer hard drive without realizing it contained $7.5 million worth of the digital currency Bitcoin.

The device is now buried somewhere in a vast landfill site near the home of owner James Howells -- who only realized his mistake when it was too late.

"It is soul destroying to be honest,” Howells told NBC News on Thursday. "I haven’t had much sleep over the past few days. Every second of the day I am thinking about what could have been."

Howells, whose ordeal was first reported by the Guardian, worked out the hard drive would have been taken to a local landfill site and visited the dump to speak to the manager.

But the hopelessness of his task became clear when he was was told that finding he disk would take weeks even with a team of a dozen people and backhoes.

"I had originally thought about raising money to hunt for the drive, but it was more an off-the-cuff idea. I know it’s gone," he said.

Howells posted an image of the landfill site on Twitter.

The hard drive is so valuable because it contains the key to 7,500 bitcoins, a currency which exists only in the digital world.

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The currency was created in 2009 and has recently skyrocketed in value -- hitting $1,000 per unit on Wednesday -- having enjoyed a surge in interest by the media and financial sector.

Howells, from Newport, in South Wales, created his 7,500 bitcoins in 2009, when the new currency was only known in niche circles and of little value.

"It was just after the financial crash and when I found out about Bitcoin it seemed to me to be the perfect alternative," he said. "I knew it was going to be huge."

The 28-year-old "mined" the currency by running a computer program on his Dell laptop for almost a week, eventually having to turn it off because his girlfriend complained the fans in the machine were getting too hot and noisy at night.

Howells said he was forced to take the hard drive out of the laptop in 2010 when he poured a soft drink over the keyboard, and over the next three years it remained forgotten in his desk drawer.

He does not know exactly when he threw it away, but said it was at some point this summer.

In the meantime. Bitcoin's popularity had exploded into the mainstream.

Norwegian investor Kristoffer Koch made about $800,000 when he bought $27 worth of bitcoins and forgot about them. And before it was closed by the FBI in October the illegal online marketplace Silk Road used Bitcoin to trade goods including drugs and weapons.

It was further pushed into the mainstream when Richard Branson announced this week that people would be able to pay for Virgin Galactic space flights using the currency. The first Bitcoin ATM machine opened in Vancouver, Canada, last month.

Howells only realized what he had done last Friday.

"I started hearing all these stories about people making money from Bitcoin, and basically the penny just dropped and I remembered the bitcoins on the hard drive I had thrown away,” he said. “I have turned my house upside down looking for it, but I know deep down I threw it away."

However, he refused to be too downbeat about the episode, and is now concentrating on the next opportunity the internet might bring.

"I am not about to jump off a bridge or anything," he said. "There's always going to be another opportunity."

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