They'll make synthetic fuel by pulling CO2 back out of the air:
https://www.globenewswire.com/news-release/2019/06/18/187048...
https://carbonengineering.com/news-updates/aerion-supersonic...
https://www.globenewswire.com/news-release/2019/06/18/187048...
https://carbonengineering.com/news-updates/aerion-supersonic...
I fail to see how building yet another luxury transport service will meaningfully help the world compared to tackling some of the bigger problems in energy and environment. Especially since there's no possibility that Boom is more efficient than existing modes of travel.