ABB designs and manufactures integrated electrical systems that supply reliable DC power in the most challenging environments and usually for the highest power DC processes, such as aluminium smelting, making steel from scrap metal using electric arc furnaces, and hydrogen production via electrolysis.  

The company’s high-power history in rectifier technology stretches back almost 100 years. Early designs, such as mercury arc rectifiers from the 1930s, used liquid mercury as a cathode to convert AC current into DC for applications like industrial motors and streetcars. Over time, advancements in semiconductor technology led to the development of diodes and thyristors, which offer improved safety, greater reliability, and reduced environmental risks compared to older methods. 

Today,​​​​ high-heat processes such as steel and primary aluminium production, essential to society but largely reliant on emissions-heavy burning of coal, provide an opportunity for climate change mitigation. The most significant sustainability impacts delivered by ABB’s high-power rectifiers (HPR) are in enabling industry to access ever cleaner renewable electricity supplies, while continuously and efficiently driving high-power processes. 

1. A massive solar-powered Saudi energy-transition project

ABB serves every kind of niche in the domain of hydrogen production, with a primary focus of ABB Business Unit HPR on large scale production facilities. Each plant typically hosts more than 100 ​​​​megawatts of installed electrolyzer capacity. Economies of scale will help green hydrogen – which is produced using renewable energy to split water molecules into hydrogen and oxygen – to become cost effective. 

In the Middle East, vast solar and wind resources are being funneled to power production of hydrogen for export. Never mind megawatts-scale: for this project, ABB supplied rectifier systems designed to channel more than 2 gigawatts of renewable AC output into reliable DC current that will power electrolyzers to produce up to 600 tons of carbon-free hydrogen per day.  

ABB was chosen to provide an AC to DC power conversion system along with auxiliary electrical equipment for this project, one of the world’s largest hydrogen plants, based on its proven capabilities in large scale project execution, its system design expertise and its reputation for being able to adapt to evolving customer requirements in a complex project setup. 

ABB’s global manufacturing capacity meant it was uniquely ​​​​positioned to provide rectifier systems, each built into a custom-designed eHouse for off-site manufacturing and optimizing on-site implementation. Every one of these eHouse units is about 10 meters wide by five meters deep and packed with sophisticated power electronics equipment combined with control and cooling systems. Delivering such modules took a coordinated logistical and manufacturing effort. 

Connecting the mega plant to a hybrid renewable and grid electricity supply is also not straightforward. ABB conducted power system studies, stability evaluations, thermal cycling analysis and overall system optimization – to give the customer confidence in the project’s viability at every stage of development. 

Successful, large-scale, and cost-effective hydrogen production is essential for advancing industrial sustainability. The steel industry, which is responsible for approximately 9% of global greenhouse gas emissions, can achieve long-term decarbonization by replacing coal with hydrogen. ABB’s power conversion and HPR systems are critical to enabling this transition. 

2. A new aluminium smelter that runs consistently on a fluctuating 100% renewable grid

From the super-solar zone of Saudi Arabia to Iceland, where the island grid must respond to large fluctuations in its virtually 100% renewable energy supply, and where power-hungry aluminium production is one of three main pillars of the country’s economy (after tourism and fishing). The grid and the industry don’t necessarily go well together. In this challenging environment ABB developed an innovative solution for the customer, which is among the largest aluminium plants in Europe. 

The semiconductors used in HPRs are usually diodes or thyristors. For several reasons, diodes are considered more reliable – but they are relatively simplistic devices. Thyristors, on the other hand, require active control which allows more dynamic adaptation of power output. This flexibility can be used to deliver advantages in power and energy management. However, if the electronics system fails or the control of thyristors fails, the smelting process ceases, and if the pot line equipment stands still for more than four hours the outcome can mean hundreds of millions, sometimes billions, of dollars of damage. ABB is recognized as the market leader in providing reliable thyristor rectifiers for aluminium smelting. Its thyristor control systems have been demonstrated to run without major or critical incidents for many years, if not decades. 

At the aluminium producer the pot line in Iceland is fully thyristor driven, and has an additional power electronics circuit that caters to Icelandic conditions. The ‘crowbar’ system as it’s called, is a specific device that allows reverse current flow. This means that their system is one of the only pot lines in the world with very fast load shedding and load adjustment capabilities. The resulting adaptability allows the aluminium manufacturer to operate in harmony with other grid requirements, without causing blackouts or having to stop production. 

This HPR, designed and built more than a decade ago, is one of several installations that demonstrate ABB’s ability to power industries that demand consistently high energy flows with renewable resources. 

Iceland’s hydroelectric and thermal energy sources enable the aluminium manufacturer to produce aluminium at 4 tons of CO2 per ton of metal, compared to an industry average of 14 tons of CO2 equivalent for per ton – but only with the right electrical HPR mediator between the grid and the pot line. 

3. A low-carbon clutch of electric-arc furnace steel mills

Over the past decade, ABB has powered around 10 new DC electric arc furnaces for steel production in the United States. Primarily used for scrap melting, the electric arc process is inherently less carbon intensive (at 0.3 tons of CO2 equivalent per ton of steel) than primary steel production in coal-fired blast furnaces (2.2 tons of CO2 equivalent per ton of steel). And the process is open to further carbon savings where electricity from renewable sources is plentiful. 

Scrap-based steel accounts for roughly 70% of United States production, with many arc furnaces in mini-mills situated close to the markets for their products. However, they are typically located in areas at a distance from electricity generation and are subject to weaker grids with less available short-circuit power. 

ABB has made it possible for steel companies to profitably ramp up their production using DC electric arc furnaces. Connecting electric arc furnaces to the power grid, even under challenging circumstances, is a key factor in driving sustainable, secondary steel production throughout the United States.

4. A brownfield aluminium solution that integrates existing viable assets 

ABB is extensively involved in retrofitting projects within complex industrial environments where standard solutions are not always applicable. Careful integration can allow customers to successfully keep running other significant, older assets within the plant, which avoids additional manufacturing of large industrial equipment, saving costs, carbon and downtime. 

One such example is the HPR replacement for an aluminium producer on South Africa’s east coast, which is one of the largest aluminium smelters in the southern hemisphere.  

The installed base of an ABB competitor’s equipment was already 20-30 years old. ABB is tailoring its rectifiers to fit existing transformers, and then only removing the power electronics component.  

The rectifier upgrade will greatly diminish the risk of outages, and the OPEX on frequent repairs.  

In industrial environments like this, minimizing continuous operational risk is essential. Following its power upgrade, the plant will be able to implement a maintenance schedule that poses reduced danger to service staff, and reduced threat to productivity than was possible under previous recurring emergencies. ABB’s approach is to design and tailor systems that prioritize safety above all else.

5. A 55-year-old high-power rectifier supported to keep on smelting

As ABB’s company slogan claims, its equipment and electrical designs are Engineered to outrun their scheduled lifetime.  

A key example can be found at an aluminium smelter in the Nordic region. While high-power rectifiers in the industry are commonly expected to operate for about two decades, ABB has been able to extend lifecycle support far beyond this horizon when proper maintenance strategies are in place, as demonstrated by rectifiers delivered in the 1970s that are still running reliably today.

Today, ABB’s power electronics service offering covers the full lifecycle of a system: including asset health assessment, spare parts, mechanical parts replacement, heatsink and cooling circuit refurbishments, protection replacements, control upgrades, cooling unit replacements and full replacement of converters. 

Lately, ABB has been consolidating the potential scope by working with key customers, going through their whole installed base together, and providing them with a regularly updated lifecycle plan. It typically details when to schedule various maintenance procedures, and flags when funds will be needed for service investments.