US hydrogen technology company Plug Power Inc (<a href="https://www.nasdaq.com/market-activity/stocks/plug" target="_blank">NASDAQ:PLUG</a>) has switched on the first on-site electrolyser system owned by Amazon.com Inc (<a href="https://www.nasdaq.com/market-activity/stocks/amzn" target="_blank">NASDAQ:AMZN</a>), a 1-MW machine located at the US e-commerce giant's fulfilment centre in Aurora, Colorado.