The OpenBSD Foundation reportedly spends around $20,000 USD annually on electricity costs. Their electrical costs are attributed to their build servers, which are expensive to maintain because there's so many of them as OpenBSD supports a great number of architectures. OpenBSD still supports more than a dozen CPU architectures from AMD64 to SGI and VAX, thus having lots of hardware to power.
The OpenBSD Foundation hasn't been able to meet their electricity costs and thus they've been coming out with urgent requests for sponsorship and pleas for help by Theo de Raadt.
Theo de Raadt wrote, "We really need even more funding beyond that, because otherwise all of this is simply unsustainable. This request is the smallest we can make."
Bob Beck of the foundation added, "In light of shrinking funding, we do need to look for a source to cover project expenses. If need be the OpenBSD Foundation can be involved in receiving donations to cover project electrical costs. But the fact is right now, OpenBSD will shut down if we do not have the funding to keep the lights on."
So far no company has come forward to sponsor their electricity needs. The OpenBSD developers also appear to be uninterested in dropping the number of architectures they maintain for their open-source operating system, in order to reduce the number of build servers needed and their electricity costs. While some of the supported OpenBSD architectures are likely seldom used, Theo's response to that suggestion was, "we find real and serious bugs which affect all platforms, but they are incidentally made visible on one of the platforms we run, following that they are fixed. It is a harsh reality which static and dynamic analysis tools have not yet resolved. Now, If you don't realize this is the reason we try to run on the older platforms, I am sorry but you have really not tried to stay in the loop of what makes OpenBSD a vibrant ecosystem."