The Dresser-Rand business, part of Siemens Power and Gas, has developed a new turbine for wave power plants that operates on the oscillating wave column principle.
The Dresser-Rand business developed an impulse turbine, called HydroAir, that significantly improves the financial feasibility of wave energy power plants, according to the company.
The HydroAir turbine operates at up to 75% efficiency with a power rating of 1MW, according to Siemens, and is designed for wave power plants based on the oscillating wave column (OWC) principle.
The waves move beneath a chimney-like chamber partly submerged in the water and alternately push the air upward and suction it downward, creating airflow that drives the turbine.
According to Siemens, the challenge lies in the fact that the airflow changes direction and that its power varies widely between 0 and 100%, depending on variations in waves.
To meet the challenge, the engineers at the Dresser-Rand business developed a housing that extends ‘funnel-like’ from the two sides of the turbine.
Inside, guide vanes direct the air toward the turbine’s rotor. The guide vanes on the two sides are oppositely oriented so that the inlet and outlet air always drives the rotor in the same rotational direction.
The tapered housing, called ‘variable radius’, is the key to the HydroAir turbine’s high efficiency, according to Siemens, as it guides small amounts of air so that the turbine can optimally use even minute airflows.
The guide vanes decelerate the inflowing air masses, inducing a controlled, rotating motion, thereby preventing turbulence in the airflow and reducing turbulence-induced losses by about 50%, Siemens said.
The HydroAir’s housing comprises a combination of stainless steel, aluminum, and reinforced composites, and the technology can be deployed onshore, nearshore, or offshore.