Posted At : April 13, 2009

PG&E has asked California state regulators for permission to sign a power purchase agreement with startup Solaren Corp. for up to 200 megawatts of solar power that would be beamed to earth from space, according the Wall Street Journal.

The proposed 15-year contract calls for the power collected by an orbiting solar array to be beamed by microwaves to an Earth station in Fresno. There the energy would be converted to electricity and fed into PG&E's power grid. If the plan comes to fruition, the space solar generator system would deliver about 850 gigawatt-hours of solar power in the first year of operation. The intended start date for the system to be in place is 2016.

Such systems, dubbed Space-based Solar Power (SBSP) systems, have been proposed and studied for many years. According to industry sources, NASA and the Department of Energy have spent $80M over the last 30 years researching the concept.

Conceptually, the systems are very appealing. Place a very large solar array in an orbit where it is continuously lit. Because the array is above the atmosphere, such systems can collect significantly more solar energy and do not suffer from weather-related downtime as is the case with land-based systems. These attributes elevate (pun intended) such solar systems from an intermittent source of power to a baseload resource a power company can rely on for predictable month-to-month energy generation.

Interest in SBSP has grown in recent years for many reasons. For example, in the PG&E case, one factor is help in meeting the state renewable portfolio standard (RPS) regulating the increased use of renewable energy sources. Additional interest in the technology is coming from the Department of Defense. According to a 2007 report prepared for the National Security Space Office: “SBSP and its enabling wireless power transmission technology could facilitate extremely flexible energy on demand for combat units and installations across an entire theater, while significantly reducing dependence on vulnerable over-land fuel deliveries.”  

However, like many renewable technologies, economics and environmental reviews are likely to holdup projects and deployments.

On the economic front, there is the price of the arrays themselves and the cost to lift the arrays into geostationary orbit. The “lifting” costs are considered to be so high some researchers have proposed exotic methods such as using a space elevator to get the arrays into space.  

On the environmental approvals side, given the reaction by local communities to their views being disturbed by proposed wind turbines, one can only imagine the challenges that will be brought when people hear a high-powered beam of energy from space is going to be required for the system to work.