Another commercial spaceflight venture has taken a step forward. Early this month, aerospace firm Blue Origin successful test fired its 100,000 lb (444,840 N) thrust BE-3 liquid hydrogen/liquid oxygen engine thrust chamber. The full-power static fire test took place at the E-1 test stand at NASA's Stennis Space Center near Bay Saint Louis, Mississippi and is part of Blue Origin’s program to develop a launch system for its manned Space Vehicle.
Set up by Amazon.com founder Jeff Bezos, Blue Origin is working on a number of space projects, most notably its Shepard suborbital spacecraft. The BE-3 engine is part of Blue Origin’s Reusable Booster System (RBS), which will be used to boost the biconic-shaped Space Vehicle, which the company is also developing. The Space Vehicle and booster are part of NASA's Commercial Crew Program (CCP) intended to spur development of American manned commercial space vehicles for hire by NASA and private customers.
Blue Origin is conducting the engine test under a US$22 million dollar contract for the Commercial Crew Development Round 2 (CCDev2). As part of CCDev2, the Federal Aviation Administration and the company carried out an assessment and review of the Space Vehicle to determine if the spacecraft meets safety and mission requirements for low-Earth orbit flight. This review includes over 100 wind tunnels tests as well as assessments of the vehicle's aerodynamic design and flight and cross-range maneuverability.
Source: NASA
I am aware of hydrogen's very high specific impulse but except for docking maneuvers space applications ion engines are more efficient with much more easily handled 'fuel'. (reaction mass)
Hydrogen has a high energy density by weight but not by volume so much of that advantage is lost to the weight and the aerodynamic penalty of the larger tank.
The extremely low temperature of liquid hydrogen creates problems as well. It increases the weight of the rocket by requiring insulation and encouraging the formation of frost on the vehicle and at the same time the vaporizing hydrogen must be vented from the tank either increasing the rocket's weight and complexity of a vapor return system or venting the highly flammable gas. The extreme cold also requires more expensive materials to be used in the pumps and other pluming and prevents it from being stored in wings or other oddly shaped places.
Hydrogen is also very hard to hold onto long term. With the possible exception of graphene it migrates through everything.
Just because fuel cost aren't the largest costs it doesn't mean that money can not be saved on it.
As one amateur to another. Hydrogen is interesting but in my annalist inferior.