Everyone should have access to affordable, clean energy
Technologies such as smart grids, off-grid renewables (enabling energy access in remote areas), energy-efficient appliances and innovative energy storage solutions all make systems more resilient – as well as mitigating against climate change and enabling the rise of new business models in energy services. Multiple metals and minerals are used in the manufacturing of this tech.
Centralised electrification has been key to improvements in energy access during the past two decades, with grid extension offering the lowest cost path to electrification in areas with sufficient density and electricity demand. The power grid transmits electricity generated at different power plants and distributes it to end-users over long distances. Power plants vary based on the type of fuel used to power the generator – ranging from large scale fossil fuel and nuclear plants, through hydroelectric plants, solar and wind generation, to geothermal.
Materials used in power plant construction include concrete, graphite, carbon steel and iron, cast iron, rock, sand, gravel, ductile iron, asbestos cement, fibre-reinforced composites, aluminium, galvanised and stainless steel, lead, tin, fibreglass, polyethylene, polypropylene, polyvinylchloride, manganese, cobalt and molybdenum, silver, copper, zinc, cadmium, tellurium, indium, gallium, selenium, nickel and titanium alloys.
High-voltage transmission lines (delivering electricity to end users) are made of aluminium alloy reinforced with steel, while overhead power lines are supported by steel towers. Transformers used in power supply are made of silicon steel or amorphous steel cores. Typical outdoor substation constructions include wood poles, steel lattice towers and tubular metal structures, whereas indoor substations may be gas-insulated or metal-enclosed switchgears.
Off-grid solutions are an option for nearly two thirds of people affected by lack of energy access, often in remote rural areas where costs of extending the centralised grid system would be prohibitive.
Essentially, off-grid is a power system run by a local electrical utility. Depending on the type of the solution (stand-alone off-grid, battery-based or battery-less grid-tied) the off-grid system typically includes energy generation technology (solar, wind, micro-hydro turbine), combined heat and power, a battery (for power storage), inverter, and connections to the utility grid. Depending on their size and whether they are connected to the grid, these off-grid solutions are labelled as micro-, mini- and nano-grids.
Materials used in off-grid solutions include lithium, cobalt, manganese and nickel (for batteries), aluminium, iron, lead, nickel, silver, copper, zinc, cadmium, tellurium, indium, gallium, and selenium (for solar panels) and galvanised and stainless steel, cast iron, aluminium, copper, lead, tin, manganese, nickel, cobalt, molybdenum, concrete, fibreglass, polyethylene, polypropylene and polyvinylchloride (for wind turbines). Lines connecting energy generation technologies with buildings (and potentially the utility grid) are made of aluminium and copper.
Combined heat and power (CHP) is used to recover most of heat potentially gone wasted while producing electricity, and use it for space heating and hot water. These systems are made of pipes, pumps, valves, thermal sensors, heat-store, heat dump, heat exchangers and expansion tanks of carbon or stainless steel. Pairing off-grid systems with energy-efficient appliances (such as LEDs and low-power TVs), smart meters, and pay-as-you-go business models facilitated by mobile payments, helps limit CO2 emissions while reducing stress on grids.
Energy storage is the process of capturing energy produced at a specific point in time for it to be released into the grid when it is needed. This helps to balance supply and demand – particularly for intermittent sources of energy, such as solar and wind. Energy storage technologies can be divided into short-term or long-term energy storage solutions, and mechanical, thermal or electrochemical technologies.
Bulk energy storage capacity is dominated by pumped hydroelectric storage dams and pipelines, utilising steel reinforced concrete. Mechanical storage technologies include compressed air storage, rail energy storage, and flywheels (a rotational mechanism for storing kinetic energy and providing short-duration storage, made from beryllium alloys, high-strength steels and aluminium-copper and aluminium-magnesium alloys).
Supercapacitators (also called electric double layer capacitators) are an example of short-term storage with high capacity, predominantly used in consumer electronics, transport and in grid applications (where they help stabilising renewable energy generation). They comprise two metal foils, coated with carbon or graphene-based materials and separated by an ion permeable membrane, and finally rolled into cylindrical aluminium cans.
For long-duration storage, solid state batteries offer a range of electrochemical storage possibilities. Lead-acid are the oldest and the most commonly used type of rechargeable batteries – made from lead alloy, antimony, calcium, tin and selenium. Other commercially proven battery technologies are nickel-cadmium and nickel-metal hydride. They use nickel hydroxide, and metallic cadmium or a hydrogen-absorbing alloy containing a mixture of rare earths (lanthanum, cerium, neodymium, and praseodymium) and nickel, cobalt, manganese, or aluminium. Furthermore, lithium-ion batteries (made of lithium, cobalt, manganese and nickel) are a key energy storage technology for portable electronic devices and hybrid electric vehicles.
A large proportion of the global population continues to rely on solid biomass, kerosene and coal for cooking fuel. Shifting away from traditional stoves and fuels, and towards clean cooking solutions, provides an opportunity to realise near-term climate and health co-benefits.
Besides cleanness and efficiency, sustainable cooking solutions should reflect cultural, social and gender needs, as well as availability of local fuels (given that many households have no access to alternative fuels such as electricity and LPG). Solutions can be classified into ‘improved’ and ‘clean’. The former ranges from artisan-produced coal or biomass chimneys with some functional improvements in fuel efficiency, to new rocket-style designs – including portable rocket stoves, fixed rocket chimneys and low-CO2 charcoal stoves.
Clean cooking solutions include more advanced stoves (fan jets or natural draft biomass gasifiers with very high fuel and combustion efficiencies), modern fuel stoves relying on fossil fuels or electricity (natural gas, liquefied petroleum gas and dimethyl ether) and renewable fuel stoves which derive energy from renewable non-wood fuel energy sources (e.g. biogas, ethanol, methanol). Cooking technologies tend to be simple constructions, most commonly made of brick, cement, clay, ceramic and metal, with the latter offering more varied design potential and higher quality control for manufacturing. To prevent corrosion (which develops during combustion of biomass fuels), stainless steel, iron-chromium-aluminium and iron-chromium-silicon are considered as the most suitable and cost-efficient metal alloy materials.