Germany remains the leader in the EU in terms of wind energy, but China is the world leader, with total installed capacity reached 115 GW in 2014 (data of Global Wind Energy Council GWEC). It is no great surprise that equipment for wind turbines is getting the area of interest for scientists involved in basalt composites.
In June 2014 a group of researchers from Petronas Technical University, Malaysia, presented a survey: “Basalt Carbon Hybrid Composite for Wind Turbine Rotor Blades: A Short Review”, summing up:
“Wind turbine blades are the major structural element and highest cost component in the wind power system. Modern wind turbine blade sizes are increasing, and the driving motivation behind this is to increase the efficiency and energy output per unit rotor area, and to reduce the cost per kilowatt hour.
However due to the increase in blade size, the choice of material has become the critical issue. To achieve the desired design of wind turbine blades the following aspects should be taken into consideration, among them – high fatigue strength, less weight, less cost and potential of recycling.
Basalt fiber is a relative newcomer among fiber reinforced polymers and structural composites. Basalt fiber with its excellent mechanical properties represents an interesting option in the range of composite materials for modern wind turbine blades.
Some manufacturers claim that basalt fiber has similar or better properties than S-2 glass fiber and it’s cheaper than carbon fiber. A combination of basalt fiber and carbon fiber represents the most advanced and interesting trend in hybrid technologies.
This paper reviews extraordinary properties of basalt fiber over other fiber reinforced composites and highlights how the basalt special properties together with carbon fiber will reduce the weight and cost of wind turbine blades while improving their performance. This paper also demonstrates why the basalt carbon hybrid composite material can become an ideal alternative for the wind turbine rotor blades.”
A group of scientists under the direction of Nikoloz Chikhradze from the Georgian Technical University, Tbilisi, conducted the similar research: “Hybrid fiber and nanopowder reinforced composites for wind turbine blades”. They came to the following conclusions:
“1. Currently, we have significant knowledge on the development of composite materials with reinforcing hybrid fibers. However, the data on physical-mechanical properties with hybrid basalt fibers as well as the variation of these properties under expected operating conditions are extremely limited, which delays their application as structural materials.
2. With the addition of 7% mass of silicon carbide to the epoxy resin, an 11% increase in static strength and a 24% increase in elastic modulus were obtained. An addition of basalt powder to the resin in same amount leads to increases of 15% and 25%, respectively. From these data, the effect of the reinforcement of epoxy resin by basalt powders deserves attention because basalt is a highly available and cheap reinforcement for a wide range of resins.
3.The endurance coefficient of samples containing silicon carbide and basalt powders under cyclic alternating loads at a frequency of 100 min−1 is in the range of 0.21–0.24.
4.The short-term strength of elementary basalt fiber is 2000 MPa. The coefficient of long-term strength of the roving with linear density of 110–130 tex is equal to 0.25–0.30.
5.The coefficient of endurance of the composite fabricated with epoxy matrix and high-strength, high-modulus carbon fiber is 0.25. In the hybrid composite, with partial replacement of carbon fiber by high-strength basalt fiber (at 20% or at 40%), the endurance coefficient is 0.22 and 0.18, respectively. Thus by replacing carbon fibers with the more inexpensive basalt fibers, the material may maintain its work capacity under torsion.
6.The proposed time extrapolation of a wind turbine at elevated temperature (up to 330 K) estimated for 35 years, causes the reduction of the COC on bending of composites based on epoxy matrix, carbon and glass fibers being considered in present work up to 0.75–0.80.
7.Under the same conditions, the reduction of COC of composites with hybrid reinforcement (carbon, glass, basalt) is also observed but does not go below 0.62, which is acceptable.
8.Thus, in the manufacture of wind turbine blades, a partial substitution (up to 20–30%) with basalt fibers is recommended in place of the expensive high-strength high-module carbon fibers.”
Open access to the research: “Hybrid fiber and nanopowder reinforced composites for wind turbine blades” is available due to the sponsor support of the Brazil Association of Metallurgy, Materials and Minerals (Associação Brasileira de Metalurgia, Materiais e Mineração).
As a reminder: in summer this year, the representatives of the Russian JSC “Basalt Projects” signed a memorandum of cooperation with the delegation from the Brazilian state of Parana.
Nikoloz M. Chikhradze¹,², Fernand D.S. Marquis³, Guram S. Abashidze²
¹ Georgian Technical University, Tbilisi, Georgia
² G Tsulukidze Mining Institute of Georgia, Tbilisi, Georgia
³ Department of Systems Engineering, Naval Postgraduate School, Wayne Mayer Institute of Systems Engineering, Monterey, USA