Sun and wind tracking actuators provide compact reliability for sustainable energy generation

Sun and wind tracking actuators provide compact reliability for sustainable energy generation

Solar and wind power arrays used by energy authorities to generate sustainable, cheaper electricity require continuous re-orientation to obtain maximum energy from the sun and wind.

Low maintenance Airstroke® actuators from Firestone provide a compact and easily installed way to facilitate robust and reliable engineering of clean green renewable energy installations needing to continuously orient solar and wind power arrays towards their source of energy.

The simple pneumatic actuators can be installed in solar arrays and within wind power structures to continuously orient their generating surfaces in the most favourable position to optimise the amount of energy produced from natural sources.

In actuation capacities from just a few dozen kilograms to more than 40 tons a unit, and functioning reliably for millions of cycles, Airstrokes are proven worldwide in demanding covered and outdoor applications ranging from conveyors and vibrating screens though to splitting a giant Australian mining dragline for maintenance. Their complementary fabric-and-rubber Airmount® isolators deliver isolation efficiencies frequently exceeding 99 per cent to protect sensitive plant from damage from ambient noise vibration and harshness (NVH) and to reduce NVH emissions from installed plant.

“These proven actuators respond to global renewables engineering trends which require proven low-maintenance actuation,” says Mr James Maslin, Technical Product Manager for Firestone Industrial National Distributor Air Springs Supply. Both the Airstroke and Airmount product are identical in construction to the air springs used as suspension in heavy trucks covering hundreds of thousands of kilometres in some of the harshest conditions Australia has to offer.

The rubber and fabric actuators solve the problem of stationary solar collection panels becoming inefficient as the sun shifts from a 90-degree angle to the panels, or where wind generators must be smoothly re-oriented to harvest the maximum energy from changing winds. Usually inflated or deflated by standard fixed or mobile compressed air (typically the ubiquitous 7 bar (100 psi) compressor equipment used throughout Australia), they can continuously reorient photovoltaic systems to minimise and angle of incidence between the incoming sunlight and a photovoltaic array, or to achieve the most favourable angle for Wind generation.

“Typically, these very simple and robust actuators will give millions of cycles in service without needing maintenance, because they don’t have any of the rods, seals and complexity of usual hydraulic and pneumatic actuators,” says Mr Maslin. “Usually they are powered by the simple type of compressed air equipment found in industrial plants throughout Australia, although we have heard of an ingenious actuation alternative that uses the expansion and contraction of Freon gas as it is heated and cooled within the solar power actuators to extend and retract them and change the angle of the collection panels (as per illustration below). Airstroke actuators filled with fluid have also been used for heavy actuation, such as splitting a mining dragline for maintenance, so they can handle very heavy loads where required.”

Compact Firestone Air Springs, right, offer smooth actuation for solar trackers, left. Unlike conventional pneumatic cylinders, they contain no rods or seals to break or wear and triple convoluted model

“Airstrokes are particularly beneficial for installations where continuous focusing through single or dual-axis arrangements enhances energy returns. Such installations – sometimes in remote locations and subject to climatic extremes over 24 hours – need extremely reliable actuators to continuously reposition payloads, including solar panels and reflectors,” says Mr Maslin.

Airstroke and Airmount bellows offered by for use by energy engineers and installers have been proven in widespread heavy duty industrial actuation throughout Australia, including providing millions of cycles of service on conveyors and mineral processing screens and vibrators, where they have to withstand dust, heat, moisture and extremes of Outback climate.

“They are identical in construction to the airbags proven in truck and train suspension, so they are extraordinarily tough. In addition to having no internal rods of seals to wear – unlike conventional metal cylinders – they have the ability to rotate through an angle without a clevis,” says Mr Maslin.

In addition to making air springs easy to install in compact spaces, this ability to bend with load (and to tolerate high side loadings) means the air springs will perform where more rigid alternatives would break or wear.

Advantages of Air Springs

  • Cost. Air springs can be used instead of more expensive hydraulic systems when applying large forces. Sizes are available from fewer than 80mm to more than nearly 1000mm (3in to 38in) in diameter, in single, double and triple convolutions in actuation capacities from just a few dozen kilograms to more than 40 tons a unit.
  • Suitability for aggressive environments. Since there are no seals sliding against exposed surfaces, an air spring can often survive abrasive and corrosive environments that require special consideration when a conventional cylinder is used.
  • Compact installation. The way a flexible-wall air spring operates is as follows: it is compressed to its minimum height then extends when pressure is applied. In most cases, the minimum height is considerably less than the available stroke. As a result, air springs can be put in a very compact space and extended to more than twice their starting height.
  • Ease of attachment and low maintenance. Since the bellows bends, its bead plates don’t have to remain parallel. No lubrication is required once it is in place. The lack of seals also means lack of friction and jerkiness in operation.