CleanSpark’s total revenue rose 400% in its 2021 fiscal year, but the sustainable bitcoin mining and energy technology company also recorded a net loss of $21.8 million, or $0.75 per share, it announced on Tuesday.

For the year ended Sept. 30, CleanSpark generated $49.4 million in revenue, up from about $10 million the previous year. More than $27 million came in its fourth quarter as bitcoin’s price rose. The net loss was slightly less than the $23.3 million or $2.44 per share loss for its 2020 fiscal year.

CleanSpark’s adjusted EBITDA for the year was $9 million or a $0.31 gain per share versus a $10.2 million, $1.07 loss per share compared with the same period a year ago.

The company has been expanding significantly over the last eight months. In April, it signed contracts to purchase 22,680 bitcoin mining machines.

In August, CleanSpark acquired a second data center in Norcross, Ga. for $6.5 million, and over the last two months has purchased additional mining machines. More recently, it announced that it had bought 20-megawatt, immersion cooling infrastructure for the Norcross facility to boost its mining efficiency by over 20%.

The company’s current has a current hashrate of 1.3 exahash per second, which it intends to increase with its additional mining power.

In an earnings call Tuesday, CleanSpark CEO Zach Bradford called CleanSpark “incredibly undervalued” and highlighted the company’s energy expertise. “We are deploying advanced technologies like renewable energy assets and immersion cooling to make our operations more efficient,” Bradford said. “These efficiency enhancements are expected to increase production and decrease operating costs at all our facilities.”