CHALLENGE #4 – Tasso A/S
Tasso A/S is a foundry that produces continuous cast iron, which e.g. is used for the hydraulic systems in wind turbines. Manufacturing of cast iron involves some highly energy-consuming processes. Today, Tasso works systematically with SDG no. 12 “Responsible Consumption and Production” because this is where the company can make a real difference to environment and their business. Several of their costumers are setting new high ambitions to reduce the CO2 footprint from the total supply chain.
Three students, from the engineering school in Aarhus, have investigated different possibilities for Tasso A/S to reduce their carbon footprint. Tasso A/S has delivered the total energy consumption on a yearly basis and the electric energy consumption with a higher resolution, which is the primary energy source in the production of cast iron. Other energy sources that Tasso A/S uses are diesel, natural gas, LP and district heating.
The investigation has only focused on scope 1 and 2, which are direct emissions from internal functions and emissions from external energy generation.
There has been made CO2-calculations for yearly consumption of fossil fuels, heat and electricity. Moreover, analysis has been made for the electricity consumption with a higher resolution and for hourly CO2-emissions of the danish grid. The data analysis has been made in Matlab.
Afterwards, simulations was been made, where introduction of renewable energy sources has been investigated with regards to costs and possible CO2-reductions.
There are different ways of reducing the carbon footprint. Some have direct impact while others are more indirect. There has been looked at reducing or replacing fossil fuels, timeshifted consumption and investment of renew-able energy.
Fossil fuels and timeshifted consumption
To make a local impact on CO2-emissions, Tasso A/S can consider replacing the burners using fossil fuels with electrical based heaters. That kind of investment will continuously reduce the carbon emissions by following the development of the grid. Though it depends on the demand for electrical energy to heat the line to an acceptable level.
Tasso A/S can have advantages of looking into their fuel consumption and electricity consumption. It is seen that their consumption per tons produced iron has increased a little during the past 10 years. Especially when comparing electricity in 2019 with 2017 an increase by approximately 20 kWh per ton is seen without knowing the reason. The reduction of tons CO2 per ton produced cast iron, and their total emissions in general, is mainly due to a reduction in CO2-emissions of the energy in the electrical grid. The change in CO2-emissions when timeshifting the electricity consumption is small as expected, as both consumption and the CO2/kWh is almost constant during the day.
Investment of renewable energy sources
The simulations of renewable energy show that the price of photo voltaic is too high to make a good business case. On the other hand, the wind turbines have an interesting business case.
One of the factors that has an impact on the business case is the electricity price. As the electricity price, Tasso A/S pays, is low compared to private consumers, the savings per kWh will be lower than for private consumers. On the other hand, excess electricity production will be more attractive to sell, as it has almost the same value as bought electricity.
When looking at the investment of RES from the CO2-perspective it is relevant to discuss their impact. When constructing some sort of renewable energy source in a different location than where the actual consumption is, then every consumer connected to the grid reduces their emissions a bit, as the produced energy is injected to the grid.
If Tasso A/S makes an investment in RES, the produced electricity of this source could get a certificate, which proves the energy’s origin. When this energy is used, the credits for RE goes back to Tasso A/S when using the marked-based method of scope 2 in the GHG protocol. If Tasso A/S makes an investment in for example wind turbines which equals their consumption over a whole year, then they can state themselves as CO2-neutral, as of the present definitions.
This is not how it is calculated in this project, as only RE, which is present at consumption time, is used. It is important to notice that the calculation of a CO2-reduction depends on the method which is used at that time. Therefore, a CO2-reduction from today, will not necessarily be the same reduction in 10 years, due to the possible change in its definition.
Simulation of renewable energy sources
It is simulated that Tasso A/S could get a renewable energy penetration (REP) of 44.5% if investing in 3 MW wind turbines. The 44.9% REP is for a case where Tasso A/S is connected direct to the wind turbines and represents the energy that, they can consume based on the production according to weather data. With some sort of electric energy storage, they could be able to use all of the produced energy from the wind turbines resulting in a REP of 59.1%. The simulation is performed with offshore wind turbines outside of Esbjerg, because the actual location in Odense is not a practical solution.
It is worth to consider the difference between buying existing RES and buying and installing new RES. Buying existing RES will probably give Tasso A/S a certificate of using green energy, but it will not add any green energy to the grid, as somebody just give up their RES. By buying and installing new RES, the company will help to increase the share of RE in the grid and thereby making everyone greener. It has not been investigated what difference, there is in these two cases, when reporting CO2-emissions to the GHG protocol.
It can be concluded that there is a potential for reduction in their energy consumptions, both electricity and fossil fuels. Moreover, replacement of the current fossil fuels with electricity can reduce the yearly CO2-emissions.
Investment of renewable energy sources (RES) has been investigated and it can be concluded that a CO2-reduction of 1.8-32.8% can be achieved depending on the case. The wind turbines give a much higher reduction compared to the investment. It can also be concluded that the LCOE of solar power is higher than the current LCOE and therefore not an attractive business case. However, it seems like the wind turbines can be a good business case, though it shall be mentioned that the economic calculations have not been the focus and it is necessary to investigate this in more details. The investment of RES also has to be considered regarding the CO2-reduction, and there is a chance that there will come fees or other economic aspects related to the CO2, which can turn the investment into a good business case in the near future.
As a result of the knowledge, points and simulation results discussed in this work, Tasso A/S is now considering looking more into investing in wind turbines as a tool to reduce their carbon footprint and as a business case.
Future work can be to investigate their consumption and how they can reduce this and streamline it, before investing in RES as they then will not need as much energy. They can also look more into the potential of extraction of heat energy. Different parts of the production releases large amounts of heat, that could be used to heat up water and probably run a turbine.
The project was undertaken by three students from Aarhus University School of Engineering on 6th semester of Electrical Energy Technology, Lea Kornbeck Askholm, Jonas Fribo Sørensen and Mathias Stegger Jørgensen.
The project has been a part of the course “Energy System Integration” by Assistant Professor Corneliu Barbu and has been completed by making a scientific article and results has been presented for Tasso A/S.
Thank you to Tasso A/S for the great collaboration.