Thermodynamic Analysis of a Highly Pressurized CO2 Cycle for Renewable Energy Applications

2020 ◽  
Author(s):  
Geoffrey R. Kemmerer ◽  
Thomas Gross ◽  
Kevin R. Anderson
Keyword(s):  
High Pressure ◽  
Renewable Energy ◽  
Alternative Energy ◽  
High Pressures ◽  
Maximum Energy ◽  
Coefficient Of Performance ◽  
Modeling And Analysis ◽  
Energy Applications ◽  
Turbo Expander ◽  
Carbon Dioxide Co2

Abstract Refrigerated gases have been used to store energy with limited success. This paper presents the results of an exploratory study of how the behavior of fluids compressed to high pressures can be used to increase the efficiency of refrigeration cycles and one possible application for renewable energy. This research presents the results of thermodynamic modeling and analysis of a novel Carbon Dioxide (CO2) cycle to be used for alternative energy production. The thermodynamic computational simulations are carried out in MATLAB and use the NIST REFPROP database for modeling the high pressure (on the order of 1000 MPa) CO2 state points. Preliminary results show that the maximum energy that can be recovered using the proposed high pressure cycle in on the order of 11,043 J, for each mole of CO2 flowing in the cycle. Thus the Coefficient of Performance is COP = 2.22, and the efficiency of the cycle is estimated as η = 35%. Future work will focus on the development of equipment such as the cryogenic turbo-expander that can operate at the ultra-high pressures studied.

scholarly journals Experiments with CO<sub>2</sub>-in-air reference gases in high-pressure aluminum cylinders

2018 ◽  
Vol 11 (10) ◽  
pp. 5565-5586 ◽  
Author(s):  
Michael F. Schibig ◽  
Duane Kitzis ◽  
Pieter P. Tans
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
High Pressures ◽  
Co2 Enrichment ◽  
Low Flow ◽  
Cylinder Wall ◽  
Practical Applications ◽  
Sources And Sinks ◽  
Carbon Dioxide Co2 ◽  
Adsorption Desorption

Abstract. Long-term monitoring of carbon dioxide (CO2) in the atmosphere is key for a better understanding of the processes involved in the carbon cycle that have a major impact on further climate change. Keeping track of large-scale emissions and removals (sources and sinks) of CO2 requires very accurate measurements. They all have to be calibrated very carefully and have to be traceable to a common scale, the World Meteorological Organization (WMO) CO2 X2007 scale, which is maintained by the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL) in Boulder, CO, USA. The international WMO GAW (Global Atmosphere Watch) program sets as compatibility goals for the required agreement between different methods and laboratories ±0.1 µmol mol−1 for the Northern Hemisphere and ±0.05 µmol mol−1 for the Southern Hemisphere. The reference gas mixtures used to pass down and distribute the scale are stored in high-pressure aluminum cylinders. It is crucial that the standards remain stable during their entire time of use. In this study the tested vertically positioned aluminum cylinders showed similar CO2 enrichment during low-flow conditions (0.3 L min−1), which are similar to flows often used for calibration gases in practical applications. The average CO2 enrichment was 0.090±0.009 µmol mol−1 as the cylinder was emptied from about 150 to 1 bar above atmosphere. However, it is important to note that the enrichment is not linear but follows Langmuir's adsorption–desorption model, where the CO2 enrichment is almost negligible at high pressures but much more pronounced at low pressures. When decanted at a higher rate of 5.0 L min−1 the enrichment becomes 0.22±0.05 µmol mol−1 for the same pressure drop. The higher enrichment is related to thermal diffusion and fractionation effects in the cylinder, which were also dependent on the cylinder's orientation and could even turn negative. However, the low amount of CO2 adsorbed on the cylinder wall and the fact that the main increase happens at low pressure lead to the conclusion that aluminum cylinders are suitable to store ambient CO2-in-dry-air mixtures provided they are not used below 20 bar. In cases where they are used in high-flow experiments that involve significant cylinder temperature changes, special attention has to be paid to possible fractionation effects.

scholarly journals The Purchase Decision-making Process for Renewable Heating Technologies: A Consumer Perspective

2019 ◽  
Author(s):  
◽  
Mario B. Reichler
Keyword(s):  
Decision Making ◽  
Renewable Energy ◽  
Alternative Energy ◽  
Oil And Gas ◽  
End Users ◽  
Decision Making Process ◽  
Daily News ◽  
Renewable Energy Technologies ◽  
Energy Technologies ◽  
Carbon Dioxide Co2

The discussion about energy has become an important topic in recent years. For end users, issues, such as price increases for oil and gas, limited resources, and alternative energy sources, have become increasingly important, attracting the attention of scholars and politicians alike. Political discussions on energy issues form part of the daily news. For example, pollution of the environment with carbon dioxide (CO2) and global warming due to the greenhouse effect have become hot topics for debate. Considering the growing importance of renewable energy for households, this investigation focuses on the factors that drive homeowners to purchase renewable energy technologies, as well as on the implications of these factors on the design of future business-to-consumer (B2C) marketing models that can contribute towards an increase in the use of renewable energy. Contextually, the research is based on heating consumption in German households. This thesis examines the potential purchase of existing renewable energy technologies by end users in the German housing market. The increased use of renewable energy is not studied with a view towards future technologies, but rather in terms of the decisionmaking process of end users to possibly invest in already available renewable heating technologies. Decision-making processes are seen as discrete activities which involve individuals over a period of time. These processes include selection and implementation, and have an end point (Wilson, 2004). Based on a grounded research methodology, a series of interviews have been carried out with homeowners as decision-makers for the purchase of existing renewable energy heating systems. The interviewees are homeowners who live in old houses with bad insulation and heating technology standards, still constituting a high proportion of homeowners in Germany. The understanding of their decision-making process can help managers of renewable energy companies, politicians, and local authorities develop viable strategies for increasing the purchase of renewable heating technologies. This research indicates the importance of not only rational decision-making factors as strongly economical related issues affecting the purchase of renewable heating technologies, but also of bounded rational factors influenced by the personal insights of homeowners and their relationship to involved stakeholders within the market for renewable heating technologies.

Tribological Studies of Compressor Surfaces in the Presence of Carbon Dioxide Under Extreme Environmental Pressure Conditions

2005 ◽  
Author(s):  
Nicholaos G. Demas ◽  
Andreas A. Polycarpou
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
High Pressures ◽  
Environmental Pressures ◽  
Thermodynamic Studies ◽  
Environmental Pressure ◽  
Ultra High Pressure ◽  
Carbon Dioxide Co2 ◽  
Internal Pressures ◽  
Very High

The refrigeration industry has shown an inclination towards the use of carbon dioxide (CO2) as a refrigerant in some applications. While extensive thermodynamic studies exist, tribological studies with CO2 are limited and tribological testing has further been restricted to low environmental pressures up to 1.38 MPa (200 psi) due to limitations in equipment capabilities. In this work, experiments were performed using an Ultra High Pressure Tribometer (UHPT) that was custom designed and built for tribological testing of compressor contact interfaces at very high environmental pressures up to 13.8 MPa (2000 psi). These tests demonstrate the possibility of testing at very high pressures similar to the internal pressures of CO2 compressors.

Renewable Energy on Tribal Lands: A Feasibility Study for a Biomass-to-Energy Plant on the Cocopah Reservation in Arizona

2019 ◽  
Vol 3 (1) ◽  
pp. 1-12
Author(s):  
Lauren K. D’Souza ◽  
William L. Ascher ◽  
Tanja Srebotnjak
Keyword(s):  
Renewable Energy ◽  
Alternative Energy ◽  
Renewable Energy Sources ◽  
The United States ◽  
Biomass Energy ◽  
Policy Support ◽  
Small Scale ◽  
Energy Plant ◽  
Energy Projects ◽  
Alternative Investment

Native American reservations are among the most economically disadvantaged regions in the United States; lacking access to economic and educational opportunities that are exacerbated by “energy insecurity” due to insufficient connectivity to the electric grid and power outages. Local renewable energy sources such as wind, solar, and biomass offer energy alternatives but their implementation encounters barriers such as lack of financing, infrastructure, and expertise, as well as divergent attitudes among tribal leaders. Biomass, in particular, could be a source of stable base-load power that is abundant and scalable in many rural communities. This case study examines the feasibility of a biomass energy plant on the Cocopah reservation in southwestern Arizona. It considers feedstock availability, cost and energy content, technology options, nameplate capacity, discount and interest rates, construction, operation and maintenance (O&M) costs, and alternative investment options. This study finds that at current electricity prices and based on typical costs for fuel, O&M over 30 years, none of the tested scenarios is presently cost-effective on a net present value (NPV) basis when compared with an alternative investment yielding annual returns of 3% or higher. The technology most likely to be economically viable and suitable for remote, rural contexts—a combustion stoker—resulted in a levelized costs of energy (LCOE) ranging from US$0.056 to 0.147/kWh. The most favorable scenario is a combustion stoker with an estimated NPV of US$4,791,243. The NPV of the corresponding alternative investment is US$7,123,380. However, if the tribes were able to secure a zero-interest loan to finance the plant’s installation cost, the project would be on par with the alternative investment. Even if this were the case, the scenario still relies on some of the most optimistic assumptions for the biomass-to-power plant and excludes abatement costs for air emissions. The study thus concludes that at present small-scale, biomass-to-energy projects require a mix of favorable market and local conditions as well as appropriate policy support to make biomass energy projects a cost-competitive source of stable, alternative energy for remote rural tribal communities that can provide greater tribal sovereignty and economic opportunities.

Lossless Dynamic Models of the Quasi-Z-Source Converter Family

2011 ◽  
Vol 29 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Dmitri Vinnikov ◽  
Oleksandr Husev ◽  
Indrek Roasto
Keyword(s):  
Renewable Energy ◽  
Dynamic Models ◽  
Energy Applications

Lossless Dynamic Models of the Quasi-Z-Source Converter FamilyThis paper is devoted to the quasi-Z-source (qZS) converter family. Recently, the qZS-converters have attracted attention because of their specific properties of voltage boost and buck functions with a single switching stage, which could be especially beneficial in renewable energy applications. As main representatives of the qZS-converter family, the traditional quasi-Z-source inverter as well as two novel extended boost quasi-Z-source inverters are discussed. Lossless dynamic models of these topologies are presented and analyzed.

Sign in / Sign up

Export Citation Format

Share Document