Praxair Green Technologies: More Oxygen More Green
What if you could increase the productivity of steel industry furnaces while reducing their greenhouse gas impact?
Praxair oxygen is used to make steel – more than 100 million metric tons per year worldwide. The oxygen enhances blast furnace iron production (reducing coke consumption and increasing furnace productivity). It is also used to melt and decarburize steel and frequently to increase the efficiency and lower emissions from combustion throughout the steel mill.
In 2011, Praxair estimated that using our oxygen in steelmaking avoids 8.7 million metric tons of CO2e per year.
Oxygen is a principal product of Praxair air separation units. Energy used by these units is the largest contributor to Praxair's Scope 2 GHG (indirect greenhouse gas emissions from the consumption of purchased electricity, heat or steam). The chart to the right shows that our impact on steelmaking alone significantly reduces our CO2e (carbon dioxide equivalent) impact.
The 2011 result provided in the chart was audited, see below. In addition, Praxair recalculates this result each year using the same methodology, and the results have remained consistent. Current year results are provided in Targets and Performance and in Praxair’s annual Sustainable Value Report.
Behind the Numbers
Most of the CO2e saving in steel comes from the blast furnace. Calculations for blast furnace CO2e savings in our U.S. operations are published in a Praxair White Paper (see the executive summary), and the conclusions were independently validated for North America. The global data was calculated from the North American data using global sales figures. The second major contributor to greenhouse gas emissions improvement is energy savings by oxygen injection into electric arc furnace (EAF) steelmaking. This injection saves electrical power at the expense of an efficient use of fossil fuel in the EAF. The CO2e benefit was calculated from Praxair internal steelmaking expertise and global sales figures using country emission factors.
Third Party Audit
In order to validate the calculation of the reduction in Carbon Dioxide Equivalent enabled by use of Praxair’s Blast Furnace Oxygen enrichment, Praxair hired Helios-NRG, LLC to perform an audit of the methodology, models and assumptions used in their analysis. Helios-NRG has expertise in many relevant areas including energy, combustion, hydrogen, and carbon capture/sequestration and has consulted with government agencies and private industry in these areas. Examples of past projects include consulting with the DOE in Clean Fuels, Carbon Capture and Sequestration, Advanced Gasification and Hydrogen as well as proprietary client reports in pre- and post combustion carbon capture. See the letter signed and dated on May 27, 2011 by Dr. Ravi Prasad of Helios-NRG, LLC, which documents their findings.