If you have a microwave, you will have noticed that it can heat up your food in a fraction of the time of a gas oven, and when you open it there is no stream of hot air coming out (i.e. wasted). The same goes for induction stoves: the water boils in a fraction of the time compared to a gas stove, and there is no heat flowing on the sides of the pan (i.e. wasted).
Despite the evident benefits in speed and efficiency, the popularity of microwaves, induction and other electric heating technologies in industry is quite limited. Cheap coal and natural gas have made them the go-to source for heat in industry. However, to have any chance of reaching Net Zero, this must change: no industrial company can eliminate emissions without rethinking how it generates its process heat.
Industrial Heat Today
Largely invisible to consumers, heat is the backbone of any manufacturing process: cooking, sterilizing, melting metals, promoting chemical reactions… From the fertilizer to feed the world’s growing population, to the steel and plastics for the cars we drive, and the cement for the buildings we live and work in, the world today cannot function without heat. It represents ~20% of global final energy demand and costs industry over € 300 Bn in fuel (more than € 1 Tn at 2022 spot prices) and € 30 Bn in equipment every year (boilers, furnaces and combined heat and power plants).
Generating these vast amounts of thermal energy is also a massive environmental problem, because over 75% is produced by burning fossil fuels emitting ~10% of the world’s CO2 emissions. That’s 2.5 times more than the emissions of airplanes and ships combined, close to the emissions of the entire road transport sector. Burning gas and coal also emits air pollutants such as NOx, SOx, polycyclic aromatic hydrocarbons and particulate matter, contributing to the 7 million premature deaths annually the WHO estimates are linked to air pollution.
The good news is that industrial heat is not as “hard to abate” as it may seem. Although typically associated with very high-temperature processes, like melting glass and cooking bricks, 45% of the thermal energy is used by processes below 200 °C, across a vast range of sectors, namely food and beverage, chemicals, pulp and paper, and textiles. Burning natural gas creates a flame at ~2,000 °C, so using it to heat materials at 100-200 °C is like “cutting butter with a chainsaw”.
Electric Heating Technologies And Their Benefits
Existing electric heating technologies can already substitute fossil fuels in ~80% of applications, and including those under development 99% of use cases can be electrified. When powered by renewable energy, electric heating eliminates 100% of greenhouse and pollutants emissions, and delivers efficiency, process and system benefits. While green hydrogen technically could be seen as a way to “indirectly” electrify heat generation, I don’t believe it will see meaningful adoption in this application for a variety of reasons that would need a dedicated piece (partly covered here), therefore the focus of this article is on “direct” electric heating technologies.
Industrial Heat Pumps, similarly to residential heat pumps, use electricity to transfer heat from a “source” to a “sink”, rather than converting electricity into heat. By utilising residual heat from industrial processes, they can deliver temperatures up to 170 °C at 300% - 700% efficiency: 1 kWh of electricity can generate 3 to 7 kWh of heat. Heat pumps are especially suited to provide heat for cooking, drying, pickling, pressing, staining, and steaming in the paper, chemical, textile and food and beverage industries.
Resistive Heating releases heat when an electric current passes through the resistance of a conductor. It can reach 2,400 °C and 99% conversion efficiency. A wide range of industries already use it today, for example to protect pipelines from freezing and, in consumer products, to heat seats and windows in passenger cars. Its most interesting industrial use going forward will be in replacing the 500,000 gas and coal-fired boilers in operation today to make hot water and steam.
Electromagnetic Heating converts electricity into electromagnetic radiation at different wavelengths (induction, infrared, microwave, etc.) that can deliver heat at temperatures up to 3,000 °C. Although less efficient than other electric technologies, it reaches high temperatures faster, distributes heat homogeneously and delivers precise control of heat localization, unlocking process benefits that far outweigh higher costs. Induction heating is widely used for metals melting and heat treatment and is also rapidly replacing gas stoves in residential applications. Infrared is used to heat and dry surfaces, bake food, fix coatings and dry paint in metallurgy and textiles. Microwave heating is used to cook, sterilize and pasteurize food, and to dry wood, chemicals and textiles, among others.
Electrical Arc Heating creates a stream of electrified atoms, a sort of continuous lightning bolt, that reaches by far the highest temperatures, even above 20,000 °C (much higher than fossil fuel flames, which go up to around 2,000 °C). Commonly applied in metals processing, it is used in electric arc furnaces (and in about one third of all crude steel globally) as well as in plasma torches, to cut and weld metals.
- Environmental Benefits. Electric heating powered by renewable energy eliminates 100% of CO2 and pollutants emissions. As average grid emission intensity declines, electric heating technologies provide increasing environmental benefits even if powered by the grid and not from dedicated renewable energy plant. This also hugely reduces permit burdens and times: Tesla’s solar-powered, zero-combustion battery production facility in Nevada obtained its air permit in a less than a day, compared to over six months for a typical gas-fired facility.
Efficiency Benefits. Fossil-fuelled heating systems lose 20% - 50% of their heat discharging the toxic flue gases they generate. Electric heating technologies do not generate any gas to be discharged, improving system efficiency by 30% - 100%. Different technologies deliver further benefits. Industrial heat pumps are 10 times more efficient because they exploit residual heat from other processes. Microwaves and induction reduce heat loss in surroundings areas by generating heat directly within the target material.
- Process Benefits. Electric heating systems are much easier to control, provide more precise and uniform heat distribution and, therefore, higher product quality. They also vastly improve processing speed (this is especially true of electromagnetic heating). This translates into lower production times and defects, which cut overall production costs even if the direct cost of heat increases. For example, a Danish producer of wood- processing machinery has lowered the curing time for glue from eight hours (with a traditional gas-fired kiln) to less than 30 minutes (by using radio frequency). In another case, a U.S. metal manufacturer of painted cargo racks increased the speed of curing the paint by eight times and reduced blistering defects by switching from a gas-fired oven to infrared heating.
- System Benefits. Flexibility of fuel supply and grid balancing are huge system benefits delivered by electrification. In the first case, industrial users using electricity from renewables are not locked into using one kind of fuel (gas or coal) to fire their ovens or boilers. Rather, they can choose from solar, wind, hydro, nuclear and geothermal. The Ukrainian War has shown how risky single-fuel dependency is.
Grid balancing enables decoupling electricity supply from heat demand and is possible because heat is easier and cheaper to store than electricity. Electric heating systems can be coupled with heat storage systems and operated flexibly to balance fluctuating electricity prices and variable production from solar and wind, unlocking two key benefits for efficient industrial users. First, they can be paid by the utility to provide grid balancing services and, secondly, they can benefit from lower electricity costs by exploiting intraday electricity price fluctuations, producing more heat when prices are low. An Italian utility has installed a 10 MW electric boiler to test the use for grid regulation, using the heat generated in a district heating system, and many start-ups (es: Electrified Thermal, Antora Energy…) are developing solutions to couple intermittent renewable energy with thermal energy storage solutions.
Barriers and Catalysts
Despite the size of the environmental problem and the economic opportunity, the electrification of industrial heat is largely overlooked. One key reason is that there is no single-purposed economic interest shaping policies to promote industrial heat electrification, unlike alternatives like hydrogen. Other barriers that have prevented the widespread adoption of electric technologies in industry to date are rapidly becoming anachronistic and tipping the scales in favour of electrification:
1) Cost. Today, electricity is two to four times more expensive per unit of energy than natural gas, which prevents many industrial users to even consider the electrification of heat as a possibility. However, the actual, overall benefits of electrification become evident in the total cost of ownership:
- Efficiency benefits discussed earlier reduce the amount of electricity needed to obtain the same useful thermal energy compared to a fossil fired system;
- Maintenance costs can be cut byup to 50%, depending on the technology;
- Emissions monitoring is avoided altogether, delivering savings that run in the hundreds of thousands of euros per plant;
- Carbon pricing will inevitably turn the scales in favour of renewables. Depending on the evolution of gas prices, by 2030 even rooftop solar will probably be cheaper than natural gas.
Regulation will also play a significant role: today in Europe electricity is taxed 7 times more than gas: an industrial user in 2021 paid ~40-45 €/MWh in taxes for electricity but only 6-6,5 €/MWh for natural gas. Incentives target the production but not the use of renewable electricity. A review of the energy taxation framework that, at the very least, evens the playing field between fossil fuels and electricity will reduce the cost gap. Furthermore, the animated discussion occurring in Europe on decoupling electricity prices from gas prices will increasingly favour electrification.
2) Limited Renewables Penetration. If electricity is produced by burning fossil fuels, electrifying heat production makes no sense, both from a system efficiency and environmental perspective. But renewables penetration is growing quickly: solar and wind doubled from 5% of global electricity production to 10% between 2016 and 2021. In 2021, 80% of the new power capacity installed globally had zero emissions. This is driving down average grid emissions (the amount of CO2 emitted per average kWh of electricity), and as they decline electric heating systems deliver increasingly higher environmental benefits even if they are not directly connected to a renewable energy plant. Today an electric boiler connected to the European grid already has similar emissions to a gas boiler. As average grid emissions in Europe are expected to decline by 60% by 2030, the electric boiler will become by far the greener option.
3) Lack of Will. Industrial heating systems are long-lived and have significant sunk costs. Without a strong commitment to decarbonize from top management, the decision to replace existing assets is unlikely to come from plant and process engineers. However, the pressure on industry to decarbonize is quickly mounting from all sides, creating the will needed to address emissions from industrial heat. The Science Based Target Initiative (SBTI) reports that today 1600 companies have pledged to achieve net zero emissions, up eight-fold from 200 in 2020. Countries representing over 90% of global GDP have professed commitments to Net Zero. While not all have stringent measures to target industrial decarbonization like Europe, with its Emission Trading Scheme, they will have to turn their pledges into action if they are serious about achieving their targets.
4) Lack of Knowledge. The myth that “electric heating is for low temperatures” keeps being perpetuated despite the fact that electric heating systems can reach 10x the temperature of a fossil fuel flame, preventing many non-experts from exploring electric heating opportunities. Plus, most thermal processes are managed by mechanical engineers used to combustion processes and with limited knowledge of electrical alternatives, which poses further obstacles to direct electrification: burning hydrogen seems like the obvious path for someone who has always burned gas or coal for heating.
5) Grids. Power requirements from grids will increase as industry switches from fossil fuels to electric heating. Today, industrial electricity is mostly used for lighting and motion (with motors, pumps and compressors), but using it also for heating can double power needs. The higher efficiency of electric heating technologies can mitigate this increase, especially thanks to heat pumps. One manufacturer of high temperature industrial heat pumps indicated that only 10% of his projects need an upgrade to the grid connection. Furthermore, captive power generation through solar, coupled with heat storage, can reduce reliance on the grid.
Regulators should support this transition by preventing bottlenecks caused by permits and grid connections, which can slow down the deployment speed of production and the use of renewable electricity.
Industrial decarbonization cannot happen without transforming heat generation, and direct electrification is the best way forward thanks to the environmental, efficiency, process and system benefits that direct electric heating technologies commonly used already today can deliver.
The results shown in case studies are mind-blowing: energy demand reductions of 70% AND 90% reductions in processing time are figures to make any process engineer or plant manager jump in their chair. And the economic opportunity attached to the substitution of the 500,000 fossil fuel boilers that today burn gas and coal to generate steam and other fossil-based technologies such as ovens and furnaces, should do the same for investors.
Cheap, ubiquitous, renewable electricity will enable and reward electrifying virtually all fossil-fuel uses, delivering deep economic and emissions savings.
It’s time industrial heat starts receiving the attention it deserves in the decarbonization discussion.
illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.