The discount rate is 10%, a common return asked by investors on projects involving RES [137], the annual inflation rate is 2% [138] and the Corporate Income Tax (IRC) is 21% [139].
It is considered that the power plant is built using borrowed capital, which makes up 80% of the initial investment. For this debt, and according to the Bank of Portugal (Banco de Portugal), the average interest rate on new loans to corporations is approximately 2% [140].
Table 4.11: Parameters used in the economic analysis.
Parameter Value Project lifetime 22 years
Plant lifetime 20 years Construction time 2 years
Inflation 2%
Depreciation rate 5%
Discount rate 10%
Corporate Income Tax 21%
Own capital 20%
Borrowed capital 80%
Interest rate 2%
Since the project has a time horizon of 22 years, a payback period of 13 years is targeted in the economic analysis. This is a value that is also mentioned in other projects involving hydrogen production and RES [141] [142].
Table 4.12: Technical characteristics of the CHP microturbine.
Parameter Value Rated power 600 kW Power range 15%-100%
Electrical efficiency 33%
Total efficiency 90%
During the first hours of the day, the CHP microturbine is at its minimum capacity, 90 kW.
At 6:00 h, it is raised to 300 kW, reaching its maximum power, 600 kW, at 7:00 h. By the end of the day, at 18:00 h, it is lowered to 300 kW and finally, at 19:00 h it is set back to 90 kW for the remainder of the night.
Since the density and the LHV of the two gases used to fuel the turbine are very different, a volume of 10% of hydrogen does not mean that 10% of the primary energy is obtained from that gas. To better understand what a maximum volume of 10% ofH2 means in terms of energy and mass, it is computed the hourly intake of the CHP for each gas. The results, in accordance with the electrical energy output, are presented in Table4.13.
Table 4.13: CHP hourly electrical output and fuel intake for aH2volumetric percentage of 10%.
Time range Output H2intake NG intake
hh:mm - hh:mm kWh m3/h kg/h kWh/h m3/h kg/h kWh/h 00:00 - 04:59 90 2.884 0.257 8.547 25.95 20.17 264.2 05:00 - 05:59 300 9.613 0.856 28.49 86.51 67.22 880.6 06:00 - 16:59 600 19.23 1.711 56.98 173.0 134.4 1761 17:00 - 17:59 300 9.613 0.856 28.49 86.51 67.22 880.6 18:00 - 23:59 90 2.884 0.257 8.547 25.95 20.17 264.2 Total 8190 262.4 23.36 777.8 2362 1835 24,040 Based on these data, it is possible to calculate hydrogen and natural gas consumption in terms of volume, mass and energy, given in Table4.14.
It is important to point out that in spite ofH2making up to 10% of the volume of the blend, this only represents 1.3% of the total mass, and, most significantly, only 3.1% of the total energy of the mixture. The maximum dailyH2intake is around 23.36 kg, totalling 8525 kg per year.
Table 4.14: Consumption of each gas for aH2volumetric percentage of 10%.
Parameter Total H2 Total NG consumption [%] consumption [%]
Volume 10.0 90.0
Mass 1.3 98.7
Energy 3.1 96.9
Figure 4.1: Daily load curve of the CHP microturbine.
4.2.2 Forklift fleet
The second customer is the operator of a hydrogen-powered forklift fleet, responsible for han-dling materials in a logistics centre located in the surroundings of theH2PP. It is based on theH2 MHE fleets described in Section2.7.
To operate these vehicles, the logistics centre’s warehouse is equipped with its own private HRS, to which H2 is supplied at a pressure of 500 bar via a short pipeline and a 30/500 bar compressor. Similarly to the CHP, they also operate every day of the year.
It is assumed that their HRS is fitted with a high-pressureH2storage tank of undefined capac-ity, and the maximumH2intake of this client is 5 kg/h, (as depicted in Figure4.2), making up to a maximum of 120 kg per day and 43,800 kg per year.
Figure 4.2: MaximumH2intake of the forklift fleet HRS.
4.2.3 Transportation tube trailer
The third customer is a distribution company, responsible for transporting fuel between pro-duction sites and end-users. Among other non-specified vehicles, this distributor operates a fleet ofH2tube trailers, similar to those described in Section2.5.
Given the size and capacity of the plant, this customer intends to acquire 300 kg ofH2per day, filling a 200 bar tube trailer. It has to be loaded in a period of 6 hours, as portrayed in Figure4.3, and, unless stated otherwise, the refiling process can start and end at any hour of the day. The tube trailer is filled using the plant’s 30/200 bar compressor. TheH2is later transported to its end-users, whose nature is not crucial for this analysis, but might be, for instance, a public or private HRS or an industrial facility.
Figure 4.3: Hydrogen tube trailer loading procedure.
This customer has a daily intake of 300 kg of hydrogen, adding up to 109500 kg per year.
Unlike the previous customers, in this case, it is not possible to supply the tube trailer with only a fraction of its daily demand. In other words, while the forklift fleet could receive from 0 to 5 kg ofH2 per hour and between 0 and 120 kg per day, in the case of the tube trailer it is either not supplied at all or must be fully supplied with 300 kg.
4.2.4 Comparison between customers and hydrogen price for each one
A brief comparison between the characteristics of all customers can be done. Also, it is im-portant to define a criterion for the ratio between the prices at whichH2is to be sold to each one of them. That is, the price the customer is willing to pay for theH2.
The CHP microturbine has the lowestH2demand, consuming a maximum of 23.36 kg per day and 8525 kg per year. Meanwhile, the forklift fleet takes up to 120 kg per day and 43,800 kg in a year. At last, the tube trailer either takes no hydrogen or 300 kg, with a maximum yearly amount of 109,500 kg (assuming a non-leap year).
The price at whichH2 is sold to each customer must cover, at least, energy expenses related to its production and compression. In that case, the minimum prices for each customer can be determined by:
πHCHP min2 = πeB ηELEC
·HHVH2 (4.1)
πHFL min2 = πeB ηELEC
·HHVH2+πeB·PCPFL (4.2)
πHT RSP min
2 = πeB
ηELEC
·HHVH2+πeB·PCPT RSP (4.3)
whereπeBis the average price of electricity.
However, to cover other expenses such as the costs (CAPEX and OPEX) of equipment, main-tenance, depreciation, and loan interest, among others, and to make the plant profitable, the prices obtained using Equations4.1,4.2and4.3have to be further increased, as demonstrated up ahead.
Nevertheless, the ratio between them is kept constant, unless otherwise specified.