At a climate summit in Glasgow, Scotland, last Thursday, the Microsoft founder briefly said, "The world is moving away from fossil fuels and adopting more clean and renewable sources of energy, so the oil giants who have dominated markets for more than a century may be in trouble.

Billionaire Bill Gates, who wants to invest in long-term equity, has advised avoiding oil companies.

"30 years from now, some of these oil companies will be of very little value," Gates (an outspoken advocate for investment in renewable energy and green technologies) said at the media conference, according to Axios.

Companies such as BP and Royal Dutch Shell have reportedly seen their share prices fall over the past five years, crippling oil demand and leading to heavy losses for even the largest oil and gas companies.

ExxonMobil, the largest oil and gas producer in the United States, lost $20 billion last year.

It held a market value of $275 billion, but as countries such as the United States shifted their energy policies to combat climate change and the automotive industry moved towards an electric future, investors became more skeptical about the future of oil stocks.

Gates said he believed that oil companies could easily shift their businesses from fossil fuels to cleaner energy sources.

Gates said: "We have pipeline infrastructure in the United States that can probably be modified to transport hydrogen."