re: Energy limitations for private spaceflight
It takes far more energy to launch something into space than to drive a car/truck. Consequently fuel shortages/high prices will be noticed long before the industry gets really big. You think launch costs are high now? Any viable large-scale and long-term space industry will have to utilize solar energy in the long run, either directly or indirectly. That could mean biofuels, solar electric, or solar thermal. How to use this form of energy to launch payloads off Earth's surface is a vague technical problem at the moment.