Steel, Cement, Aluminum, Paper

Steel, cement, aluminum, paper, and chemicals are the five largest industries in the world by energy consumption.

Energy for cement is taken from the IEA's Cement analysis ¹, aluminum from the IEA's Future of Petrochemicals analysis ², and the others from the IEA Sankey diagram ³. For primary energy conversions, data from Building Energy Codes Program ⁴ are used. Emissions figures are from the IEA's Industry overview ⁵.

Iron and Steel

The iron and steel industries use about 29 exajoules of primary energy worldwide ⁴, ³. World production of steel is growing rapidly, driven by industrialization in the developing world ⁶, ⁷.

Following are estimates of the average energy required to make primary steel from virgin material, primary steel using state of the art technology, steel from recycled scrap, and several potential techniques--carbon capture and sequestration, hydrogen direct reduction, and electrowinnowing--that are not yet widely used.

Sources: World Steel Association ⁸ for steel from virgin material, Worrell et al. ⁹ for state-of-the-art steelmaking, the EIA ¹⁰ for steel from scrap, and Fischedick ¹¹ for other techniques, which are not yet widely used. Calculations assume that hydrogen is produced by electrolysis from low carbon electricity. While the electrowinnowing route, which uses electricity directly to reduce iron ore, may save energy in the long run, hydrogen direct reduction is closer to commercialization and likely to be less expensive ¹¹.

Bringing all world steel production to the level of the most efficient plants could save 5 EJ ⁶ or 6 EJ ¹² of primary energy.

Cement

World cement production has grown from 2.55 billion tons in 2006 ¹³ to 4.17 billion tons in 2014 ¹⁴, with more growth projected in the coming decades due to urbanization and industrialization.

From a greenhouse gas standpoint, cement is of particular concern due to emissions from calcinating limestone to produce clinker, the key binding material. Modern cement production is responsible for the equivalent of 0.54 tons of carbon dioxide per ton of cement as direct emissions ¹⁴, or 0.9 tons total, as follows.

About half of greenhouse gas emissions from cement making come from calcination, and the other half are from energy consumption. Source: Maddalena et al. ¹⁵.

The following portrays current emissions from the full cement production process and possible improvements.

Current emissions are from Maddalena et al. ¹⁵, potential reduction from improved energy efficiency and clinker production processes are estimated by the IEA ¹⁴, and Maddalena et al. ¹⁵ estimate the potential from alternatives to clinker for binding.

Cement made with alternative binding material, such as geopolymer cement, may have lower costs ¹⁶ and emissions than cement made from clinker due to avoidance of emissions from limestone calcination ¹⁶, ¹⁷. However, alternatives are not widely used today due to logistical challenges ¹⁸ and a lack of industry standards ¹⁵, ¹⁷.

Aluminum

The world produced about 56 million tons of aluminum in the year through June 2015 ¹⁹, almost all through the Hall-Héroult process, which uses mostly electricity. Current and potential aluminum production has the following electricity needs.

Sources: world average electricity from the IEA ²⁰, state of the art from Kvande and Drabløs ²¹, secondary (recycled) aluminum from the Energy Technology Systems Analysis Programme ²², and estimates from new technology from the IEA ²⁰.

Additionally, development of an inert anode, to replace the carbon-based anodes typically used today, would prevent the release of CO₂ from dissolution of the anode ²¹.

Forestry, Pulp, and Paper

The largest share of wood products are used for fuel.

Source: Food and Agriculture Organization of the United Nations ²³.

World paper and paperboard demand is projected to grow to over 750 million tons per year by 2050 ²⁴.

The United States paper industry has the following current and potential energy needs.

Sources: The EPA's WAste Reduction Model (WARM) ²⁵ for paper from virgin pulp and recycling, and Miller et al. ²⁶ for best and potential new technology.

Paper can be recycled five to seven times before the fibers become too degraded ²⁷.

The advancement of information and communication technology has not necessarily reduced paper demand as one might expect. Access to the Internet appears to have decreased the demand for newsprint, but it may have increased the demand for office paper ²⁸, ²⁹.