טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSapir Guy
SubjectAir Pollution Reduction through the Implementation of
Circular Economy Principles and Integrated
Production of Energy and Fertilizers
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor David Broday
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The use of fossil fuels in general and coal in particular, causes emission of many air pollutants, including nitrogen oxides (NOx), which treatment options are the focuses of this study. Along with hydrocarbon emissions (VOCs), nitrogen oxides participate in tropospheric ozone formation mechanism and are a source of photochemical smog. Nitrogen oxides also cause acid precipitation ("acid rain") and may cause eutrophication of water bodies.

A variety of different measures and treatment facilities are used to reduce the emissions of nitrogen oxides to the atmosphere. These treatment processes also have environmental effects, called cross media effects. In some cases, the cross media effect is an excess dose of ammonia or even impair the energy efficiency of the electricity production process. The principles of operation are all the same, reduction of nitrogen oxides to gaseous nitrogen (N2) or preventing their formation in the first place.

In recent years, additional methods have been developed for the treatment of nitrogen oxides. These methods are based on oxidation and separation or adsorption of the reaction products, with the by-product of the process being used as a raw material for fertilizer production. This work examines the inherent advantage of implementing technologies such as Lextran or EBFGT, and the added environmental value of the by-product derived from them. Because the fertilizer industry is a heavy resources consumer, using the by-product of the power generation process has a great potential to minimize environmental damage.

It is assumed that from each kWh produced from burning of fossil fuel in Israel 0.695 g of nitric acid could be produced, saving the use of 0.188 g of ammonia. Through Life Cycle Analysis (LCA), the theoretical savings associated with environmental pollutant emissions were evaluated in various scenarios that were run using the OpenLCA software.

The results of the analysis show that the implementation of the alternative treatment results in negligible yet positive environmental impacts in almost all the metrics that were used, mainly when the electricity production is based on coal. Namely, we found a relative reduction of 0.26% in the Smog - TRACI-2.1 criterion, and a 0.30% reduction in the simplified criterion of the total nitrogen oxide emission, with the error ranging between 2.04% and 4.81%. On average, the relative error is 10 times greater than the resulting relative change, which means that in most cases there is no certainty that the implementation of the alternative process will result in any improvement in the tested metrics, and in some cases it can even result in increased pollutant emissions. Despite our negligible (and disappointing) results, the method developed and presented in this work allows a broad analysis of the benefits or disadvantages that could be achieved by using pollutant emissions from any process as raw materials, comparing it to other alternatives. We believe that it will be possible to use the method presented in this work in different scenarios in the future to test the possible advantages of assimilating "circular economy" principles in various environmental and industrial processes across the world.