Energy Potential

To measure the amount of energy that will be released from a given technology, it is useful to measure this by the amount of energy per unit weight or volume. Specific energy is given in energy content per unit weight and volumetric energy is given in energy per unit

volume. Both is referred to as the energy density in each technology or fuel. Although the SI unit for specific and volumetric energy is J/kg and J/m³ respectively, this has been converted to kWh/kg and kWh/L in this thesis. The values for specific and volumetric energy are presented in table 3.1. These values are entered into Excel and used to create a graph depicting relationship between specific and volumetric energy, and thus to show the energy potential of a given fuel in comparison to other renewable and conventional fossil fuels. The values are derived from a variety of sources depending on the available information and credibility. The methodology of extracting these values as well as the credibility of the sources are described below. This section highlights and describes the possible variance of the properties of each fuel. The variance and how these might affect the results are considered when discussing the findings. [71]

In 2020 The University of Washington, by the institute of Clean Energy released an article describing how Li-ion battery work and some of its advantages. Li-ion batteries have one of the highest energy densities of any battery technology today. The specific energy ranges from 0.10kWh/kg to 0.27kWh/kg, whilst the volumetric energy ranges from 0.25kWh/L to 0.67kWh/L. This thesis bases its assumption on this article and assume that a reasonable value for specific energy and volumetric energy is 0.18kWh/kg and 0.56kWh/L, respectively. This is slightly above-average based on the spectrum from the University of Washington. This is believed to be rational given the rapid advancement in battery technology and the fact that only high-quality batteries will be practical for ship owners. [34]

The Engineering ToolBox is a web-based toolbox that provides information on technical application design, engineering, and construction of technical applications. The toolbox provides HHV and LHV for different fuels in different states of matter. The LHV (specific energy) is given in kWh/kg is set 33.3kWh/kg. This is the same value for both liquid state and at 700bar. Iaian Staffel from the University of Birmingham provided an energy and fuel data sheet in 2011 where properties for common fuels are presented. Staffel compiled data from 26 sources to provide a comprehensive picture of each fuel’s properties, with a global reach and no particular application. Based on Staffels research the volumetric energy is set at 2.41kWh/L and 1.32kWh/L, respectively for hydrogen at liquid state and at 700bar. [72,73]

There have been a lot of studies and opinions on the use of ammonia for several decades.

In order to convince people that ammonia could be used for energy, the Ammonia Energy Association was founded. They have been promoting the use of ammonia in a sustainable energy economy since 2004. Through generating, gathering, coordinating, and disseminat-ing applicable information for the safe use of ammonia, the Ammonia Energy Association has become the leading agent of collective action for the ammonia energy industry. The executive director, Trevor Brown, wrote a literature review in 2018 on ammonia for power.

This literature review presents the combustion characteristics for ammonia in comparison with other fuels. The specific energy is calculated to be 5.22kWh/kg and the volumetric energy 4.33kWh/L. [74, 75]

The same impacts are found to equate these renewable sources to the traditional use of fossil fuels. Marine diesel, crude oil, biodiesel, and LNG are the conventional fuels being investigated. NTNU together with DNV GL has provided a presentation on the future fuels and fuel converters. In this presentation the properties of marine diesel. The specific energy is calculated to 12.22kWh/kg. IOR is an Australian company which has over 70 diesel stops across Australia. They state themselves that they always have believed in continued innovation to offer the best service to its customers. They have released the fuel energy density of some of their own products including marine diesel. IOR state that the volumetric energy of marine diesel is 10.72kWh/L, with the notion that the calorific values may vary depending on the fuel composition. The volumetric energy is assumed to be 10.72kWh/L in this thesis. [76, 77]

The world nuclear association has also provided a list over specific energy of various fuels. Crude oil has a specific energy of 42-47MJ/kg, according to the data. This thesis assumes that crude oil has a specific energy of 45MJ/kg and that it is in the center of this range. This has a value of 12.5, when converted to kWh/kg. The world nuclear association provided a range of 42-46MJ/kg for normal petro-diesel. Because bio-diesel contains around 10% oxygen, whereas petro-diesel contains no oxygen it is assumed that bio-diesel has a specific energy in the lower end of this range. This thesis therefore assumes that bio-diesel has a specific energy of 42MJ/kg, which is converted to 11.67kWh/kg. The handbook of chemistry and physics by John R. Rumble states that the volumetric energy for bio-diesel is 9.17kWh/L. The volumetric energy value for crude oil, according to IOR, is 10.75kWh/kg. [77–80]

Elgas LNG is australias leading marketer of LPG gas. They are a member of The Linde Group, which is a world-leading gases and engineering company. Elgas LNG has provided information on its products including the energy content of LNG. The specific energy for LNG is presented to be 14.86kWh/kg, whilst the volumetric energy is 6.39kWh/L. The results regarding LNG of this thesis are based on these values. The total values for specific and volumetric energy are presented in table 3.1. [81, 82]

Table 3.1: Values for specific and volumetric energy

Fuel/technology Specific energy [kWh/kg] Volumetric energy [kWh/L]

Li-ion battery 0.18 0.56