Energy and power are essential for all societies. Nickel-containing materials are now being widely used to meet the demanding conditions of the oil and gas industries and power generation, including renewable energy.
Oil and gas
Though oil itself is not corrosive, its production takes place in highly-corrosive environments. Nickel-containing alloys are essential for providing the long-term corrosion resistance needed in many components exposed to oil and gas production environments. Common components relying on nickel-containing alloys include downhole tubing and safety critical elements, wellhead and Christmas tree components and valves, pipelines, piping, vessels and heat exchangers.
Electricity generation from fossil fuels
Globally, coal, oil and natural gas remain the most important fuels for electricity generation. In most power stations, fuel is burned for heat to produce steam that drives a turbine. Nickel-containing materials are frequently selected for their corrosion and heat resistance, increasing their durability in demanding conditions found in boilers and heat exchangers. Steam temperatures and pressures are continually being increased, as this improves overall thermodynamic efficiency and reduces CO2 emissions. This requires the use of more creep-resistant materials in the turbines. Finally, the flue gas may need treatment to reduce pollution; nickel-containing materials may be needed to resist the aggressive conditions in electrostatic dust precipitators and flue gas desulphurisation (FGD)
Nickel-containing heat and corrosion resistant alloys play an important role in ensuring the integrity, durability and long-term performance of nuclear power stations. They are used in both the heat transfer and cooling systems and inside the reactor vessel.
Methods are under development for processing and disposing of radioactive waste. Nickel-containing stainless steels and high nickel alloys have already been selected for some container designs to ensure the waste is safely contained for the duration of time needed for the radioactivity to decay to safe levels - often thousands of years.
Biofuel use is growing, helping reduce net CO2 emissions to the atmosphere. These biofuels - mostly ethanol, diesel and methane - can be produced both from waste organic material and from crops grown specifically for the purpose. Nickel-containing stainless steels are selected for their corrosion resistance, ease and speed of fabrication, and wide availability.
Wind, Wave, Tidal and Hydro Power Generation
These approaches to power generation are attracting growing interest as they offer genuinely renewable energy sources. In onshore wind power nickel is used mainly in the gearing and generator components. Offshore, given the corrosive marine environment, there are many more opportunities for stainless steels. Copper-nickel alloys can also offer fouling and corrosion protection in the splash zone.
Tidal power and emerging wave power systems face similar marine corrosion and fouling environments.
Hydroelectric installations use turbines to harness the energy of the water. These can use nickel-containing alloys for both erosion and corrosion resistance to ensure the longevity of the plant.
There are three different approaches to harnessing solar energy
- Low-temperature collection
- Concentrating solar power
- Photo-voltaic systems
Low-temperature systems typically use a flat-plate collector to heat water. These can have a selective surface applied that absorbs the solar radiation effectively while not re-radiating much of the energy at the temperature of the collector. Nickel-containing stainless steels may be used for the collector and associated pipes.
Concentrating solar power uses arrays of mirrors to concentrate the solar radiation onto receivers, where the temperature can reach 500°C. The heat is transported using molten salts in heat- and corrosion-resistant stainless steel tubing. Stainless steel tanks containing molten salts are also used to store the heat.
Photo-voltaic systems generate electricity directly and may use stainless steel for the panel frames.
Geothermal energy use is already established, particularly in areas where there is volcanic or seismic activity. Heat is usually extracted by either tapping into underground hot water or by pumping water into the hot rock. In both approaches, the resulting hot water is often saline and highly corrosive. Nickel-containing stainless steels and corrosion-resistant nickel alloys are needed to withstand these conditions.
Waste to Energy
Waste incinerators are increasingly used to generate both electricity and heat for process or district heating applications. This requires eat and corrosion resistant nickel-containing materials to withstand the high temperatures and aggressive conditions in the incinerator and gas cleaning systems.
Fuel cells generate electricity by reacting an energy source such as hydrogen or methanol with an oxidising agent such as air. Different types of fuel cell exist, some of which operate at near room temperature, others much higher. This is reflected in their design and construction materials. Nickel has a role to play in nearly all types, either as part of the internal components or in the catalyst.
Fuel cells are increasingly finding applications wherever local generation of electricity is an advantage, from individual buildings to vehicles.
It is not always convenient or practical to generate electricity on demand. This is particularly true of renewable energy sources such as wind, wave, tidal and solar power. Similarly, hybrid and electric vehicles also need the capacity to store electricity. Rechargeable batteries are one way to do this.
Many types of rechargeable battery chemistries exist, each with their own characteristics, such as energy storage capacity for a given weight, operating temperature range and discharge rates. Lithium-ion battery technology has been evolving rapidly and has found widespread application in electric vehicles as well as portable tools and electronic equipment. NMC (nickel-manganese-cobalt) lithium-ion batteries is the predominant chemistry.
A more indirect approach is to use an electrolyser to create hydrogen. This can then be stored under pressure or liquefied or as a hydride. All rely on nickel-containing materials.