Having a background in sustainability and an interest in blockchain technology, I entered the concept of cryptocurrency mining powered by renewable energy into the competition. I was fortunate to be chosen as one of four South Africans to attend the event.

Unbeknown to most people, the energy required for the process of cryptocurrency mining is significant. A popularised report recently pointed out that a single Bitcoin transaction uses about as much energy as an American household uses in a week. The Ethereum network, the second largest cryptocurrency by market cap, uses more energy than Zambia.

Determined to provide a sustainable solution to these uncomfortable facts, I boarded a plane for Germany.

Walking the streets in cloudy November, one readily forgets that, for 41 years, the city of Bonn was a global capital. Declared the seat of the West German government, it quickly developed a reputation amongst American diplomats as being a sleepy hollow. One correspondent embedded there remarked that it was “half the size of a Chicago cemetery, and twice as dead”.

The city may have been ready to host a flood of visitors in days of yore, prior to the collapse of the Berlin wall. In contemporary times, however, the Bonn hotel industry is not equipped for the influx of diplomats and bureaucrats. The event organisers found a novel solution to this problem. The city is on the banks of the river Rhine. If more hotels can’t be manufactured, why not float one in?

The event was hosted on a river cruise vessel, anchored ashore. The unintended consequence of this was a remarkably creative and focused universe. The 100 participants in the hack stayed aboard, and we convened on the central deck for talks by blockchain industry professionals. After pitching ideas, we teamed up and spent the night developing them. My team comprised members from the US and Canada. We made breakthroughs on how to deploy software to let anyone with excess solar power monetize their asset by pairing it with surplus compute.

The week on the hack4climate boat flew by. Whilst I feel that direct blockchain solutions are still a while away for most applications, I do feel we can sustainably scale cryptocurrencies by unlocking dormant renewable power.