Tiina Koljonen

Nitrogen evolution from coal, peat and wood during gasification: Literature review

During gasification, fuel nitrogen is liberated mainly as ammonia, hydrogen cyanide, molecular nitrogen, or as heavy aromatic compounds, while a smaller part of the nitrogen is retained in solid char. Independent of the fuel gasified, more NH3 is formed than other nitrogenous compounds in most gasifiers. The NH3 content in the product gas seems to be dependent mainly on the nitrogen content of the fuel. The measured NH3 concentrations have varied between 150 and 10000 ppm, the lowest being for wood, which usually has a nitrogen content less than 1%, and the highest for peat and coal, which have nitrogen content varying from 0.5 to 3.0%. The fraction of the fuel nitrogen that is converted to NH3 is probably affected by several parameters, including gasification temperature, heating rate, pressure, residence time of fuel in the reactor, as well as the devolatilization rate of fuel and the nitrogen functionality in fuel structure. No detailed structural information on the nitrogen functionality of wood, peat or coal is available because no reliable methods for quantitative analysis of nitrogen groups in these complex mixtures of organic molecules have been developed. However, it is known that nitrogen in living organic tissues is mainly in proteins. In peat, nitrogen is bound in amino acids, peptides, proteins, amino sugars and probably in heterocyclic structures. The spectroscopic studies of coal indicate that most of the nitrogen is in pyrrolic and pyridinic form but also unidentified quarternary-type nitrogen has been found. The pyrolysis studies of model compounds have shown that pyridine and pyrrole release nitrogen as HCN. Proteins and aminoacids may also release NH3. The pyrolysis experiments of coal have shown that the measured NH3/HCN ratio is dependent on the heating rate. In rapid pyrolysis experiments more HCN than NH3 has been formed but in low heating rate conditions, the situation has been the reverse. It has been hypothesized that in coal pyrolysis, part of the NH3 is formed from HCN and hydrogen through secondary reactions. In fixed bed and fluidized bed reactors, longer gas-char contact time exists than in the entrained bed reactor, which may result in greater NH3/HCN ratio in the former types of reactors. The increase in temperature or decrease in pressure and residence time of fuel in the reactor will also decrease the extent of secondary reactions of char and gases, which could result in lower NH3 formation. In the gasification of peat, more NH3 is usually formed than in gasification of hard coals, which is probably partly due to direct liberation of NH3 from amino acids. In peat and wood gasification, most of the fuel nitrogen is liberated during the pyrolysis stage. During coal gasification at low temperatures (< 1200 K), most of the nitrogen is retained in char after pyrolysis and released during the char gasification stage. This means that the reactions of char nitrogen can contribute to the total NH3 conversion.

Modelling Pathways to a Low Carbon Economy for Finland

Concretizing the roadmaps outlined for moving to a low carbon economy by 2050 into detailed policies is a challenging task. Using ETSAP-TIAM as the central modeling tool, we have analyzed the implications of low carbon policies within Europe, with a special focus on the Finnish energy system. The main objective of the work was to identify cost-effective pathways for moving into a low carbon economy by 2050, by creating a set of different storylines for the future society and economy. The analysis involved also linking the energy system model to an applied general equilibrium model and a forest sector partial equilibrium model for estimating the impacts on the overall economy as well as land-use change and forestry. The scenario results indicate that Finland has good opportunities for achieving its low carbon targets by 2050 due to its large natural resources. The major uncertainties are related to the application of carbon capture and storage (CCS) and possible sustainability criteria for biomass.

Impact of the eu emissions trading directive on the energy and steel industries in Finland

Publisher Summary This chapter discusses the impact of the European Union (EU) emissions trading that is studied using a stochastic electricity price model for the Nordic electricity markets and the TIMES energy systems model to describe the development of the Finnish energy economy. The results of the models at various CO2 emission allowance price levels are used in the interpretation of the emissions trading impacts on energy and steel sector companies. The most important way to lower CO2 emissions in the energy sector in Finland is fuel changes in the direction of lower net carbon emissions. Energy companies whose production capacity is more flexible in respect of fuel type and production volumes have the best possibilities to adapt to the market changes caused by emissions trading. Growing industrial sectors, like the steel industry in Finland, cannot keep their emissions at the present level, or lower them, by changing process fuels or by improving energy efficiency. The country-specific emissions commitments and global markets of energy or emission-intensive products do not fit well together.

Pathways to Post-fossil Economy in a Well Below 2 ℃ World

We explore the pathways for mitigating climate change to at most 2 ℃ and below by imposing a representative target trajectory for radiative forcing and by range of different price trajectories for greenhouse gas emissions. Due to the inertia in both the energy and climate systems, it appears questionable whether the objective of limiting global warming to well-below 2 ℃ is achievable without considerably overshooting the target within the current century. Exceeding the constraints of the estimated carbon budget also means that the initial overshooting must be later compensated by removing the excess emissions with negative emissions, which may become very difficult without substantial technological changes leading the world into a sustainable post-fossil economy. We outline an idealised technology pathway aligning with these viewpoints. The analysis highlights the necessity for immediate mitigation action for avoiding excessive overshooting, the key role of negative emissions, and the prospects of producing synthetic fuels, chemicals and materials from renewables and carbon dioxide for enabling the transition into the post-fossil economy.

Baltic Energy Technology Scenarios 2018

Baltic Energy Technology Scenarios 2018 (BENTE) is a scenario-based energy system analysis that explores the changes in the Baltic countries’ energy systems. What are the drivers and their impacts ...