Finally, a renewable energy solution with real bite ! The vampire-powered piston engine represents the perfect marriage of mythological exploitation and thermodynamic principles. Spray holy water, vampire turns to dust (compression stroke), inject blood, vampire regenerates (power stroke). It's essentially a biological Stirling engine with fangs. The beauty is in the details—"piston knock" caused by unmatched vampire regeneration rates is a legitimate engineering concern. And the claim that vampires are "universally available" might be the most optimistic assumption in renewable energy research I've encountered in my 40 years of teaching. Who needs solar panels when you've got the undead? Just don't tell the ethics committee about your fuel source.