3.2.6. Biogas Production from Waste

The Amount of Energy from Biogas from Animal Slurry and Bird Manure

It was assumed that biogas in the Pomerania Voivodeship would be produced from liquid manure and bird droppings, as well as from municipal waste and sewage sludge. According to the data of the Central Statistical Office, the total number of cattle, pigs, and

poultry was 219,000, 772,000, and 6,499,000, respectively [83]. In order to calculate the available energy, the following assumptions were made:


Formula (8) shows the annual amount of energy that can be obtained from biogas obtained from animal slurry or bird manure:

$$\mathbf{E\_{bg}} = 0.8 \cdot 0.2 \cdot 0.6 \cdot (0.8 \cdot \mathbf{N\_{c}} \cdot \mathbf{I\_{c}} \cdot \mathbf{U\_{c}} + 0.2 \cdot \mathbf{N\_{p}} \cdot \mathbf{I\_{p}} \cdot \mathbf{U\_{p}} + 0.004 \cdot \mathbf{N\_{po}} \cdot \mathbf{I\_{po}} \cdot \mathbf{U\_{po}}) \cdot \mathbf{W\_{m}} \tag{8}$$

where: Ebg—energy from biogas obtained from animal slurry or bird manure (TJ/year), Nc, Np, Npo—number of cattle, pigs, poultry (million heads), Ic, Ip, Ipo—annual weight of animal slurry or bird droppings from a large unit count of cattle (16.4 Mg/year), pigs (15.9 Mg/year), poultry (9.8 Mg/year), Uc, Up, Upo—biogas yield from cattle slurry (50 m3/Mg), from pig slurry (55 m3/Mg), from bird manure (140 m3/Mg) [4], W m — methane's calorific value (35.73 MJ/m3).

The obtained amount of energy that can be produced every year from the utilization of biogas from animal slurry or bird manure in the Pomerania Voivodeship is 1.08 PJ (112 GWh/year of electricity and 0.68 PJ/year of heat).

### The Amount of Energy from "Landfill" Biogas

The Pomerania region generated an annual mass of municipal waste amounting to 869 thousand Mg/year (data of the Central Statistical Office, Households and Public Utility Facilities [84]). Unfortunately, only approximately 20% of the theoretical potential is represented by biogas from municipal waste.

The potential energy calculation was based on the following assumptions, assuming that the biogas yield from municipal waste is 100 m3/Mg [55]:


Formula (9) shows the amount of energy that can be obtained from biogas obtained from the biodegradable fraction of municipal waste:

$$\mathbf{E\_{bo}} = \mathbf{0.8} \cdot \mathbf{0.2} \cdot \mathbf{0.5} \mathbf{5} \cdot \mathbf{N\_{b}} \cdot \mathbf{U\_{b}} \cdot \mathbf{W\_{m}} \tag{9}$$

where: Ebo—energy from biogas from the biodegradable fraction of municipal waste (TJ/year), Nb—mass of biodegradable fraction of municipal waste (million Mg/year), Ub—biogas yield from the biodegradable fraction of municipal waste (100 m3/Mg) [53], W m—methane calorific value (35.73 MJ/m3).

The amount of energy that can be obtained annually from biogas from the biodegradable fraction of municipal waste in the Pomerania Voivodeship is 0.273 PJ/year (28 GWh/year of electricity and 0.154 PJ/year of heat).

The Amount of Energy from Biogas in Wastewater Treatment Plants

In the Pomerania Voivodeship, 44.8 million m<sup>3</sup> of municipal wastewater is treated annually [89]. It was assumed that 50% of the sewage flowing into the treatment plant would obtain sludge (constituting 1% of the sewage) and that 1 m<sup>3</sup> of sludge can be used to obtain 15 m<sup>3</sup> of biogas [88].

In order to calculate the available energy, the following assumptions were made:


Formula (10) shows the amount of energy that can be obtained from biogas obtained from sewage sludge:

$$E\_{\rm bs} = 0.8 \cdot 0.5 \cdot 0.01 \cdot 0.6 \cdot \text{V}\_{\rm bs} \cdot \text{U}\_{\rm bs} \cdot \text{W}\_{\rm m} \tag{10}$$

where: Ebs—energy from utilization biogas from sewage sludge (TJ/year), Vbs—annual volume of municipal wastewater flowing into the treatment plant (million m3/year), Ubs—biogas yield from sewage sludge (15 m3/m3) [88], W m—methane calorific value (35.73 MJ/m3).

In total, 3.4 million m<sup>3</sup> of biogas can be obtained in the Pomerania Voivodeship, i.e., approximately 0.13 PJ/year of energy (13 GWh/year of electricity and 0.07 PJ/year of heat).

### *3.3. Wind Energy in the Pomerania Voivodeship*

As shown in the wind speed map at the height of 140 m (Figure 5), it can be stated that the Pomerania Voivodeship provides very favorable conditions for wind energy generation. The Voivodeship is especially well-suited for the development of wind energy—no<sup>t</sup> only on land but also offshore. Offshore wind energy may become a flywheel for companies from the region, including shipyards, which already today produce components for the offshore industry [91].

**Figure 5.** Wind speed analysis. Height of 140 m (own study from [92]).

The total capacity of wind farms in the Pomerania Voivodeship is 786 MW. In the draft program for the development of offshore wind energy and maritime industry, taking into account the available area of the Polish exclusive economic zone (2000 km<sup>2</sup> by 2030), wind conditions, productivity, and installed power density (6 MW/km2), the theoretical potential was estimated at the level of 12 GW, with a generation potential of approximately 48–56 TWh. On the other hand, the technical potential of offshore energy was estimated to reach 7.4 GW by 2030 (Figure 6) [93].

**Figure 6.** Potential locations of offshore wind farms in Poland (own study from [93]).

The Polska Grupa Energetyczna (Polish Energy Group) and Danish Ørsted have signed an investment agreemen<sup>t</sup> aimed at the development, construction, and operation of two offshore aeroenergy projects in the Baltic Sea, with a total capacity of approximately 2.5 GW. These are the Baltica-3 Wind Power Plant, with a capacity of over 1 GW, and the Baltica-2 Wind Power Plant, with a capacity of approximately 1.5 GW. Baltica-2 and Baltica-3 are eligible for participation in 2021 in the first phase of the operation of the offshore wind support scheme in Poland for wind farms with a total capacity of 5.9 GW. This system is a result of the new act to promote electricity generation in offshore wind farms, which was announced on 3 February 2021 in the Journal of Laws [94].

The technical potential of wind energy in the Pomerania Voivodeship was calculated. For this purpose, it was assumed that 140 m turbines will be erected, which means that the height of a turbine with a blade will be 215 m (h). The "Distance Act" [56] requires that the distance from residential buildings, areas of natural protection, and promotional forest complexes should be 10 h, i.e., 2150 m. The calculations performed indicate that the total area of the available areas is 60 km2, i.e., only 0.3% of the area of the Pomerania Voivodeship (Figure 7). The amount of energy generated from aeroenergy in the Pomerania Voivodeship is 5.68 PJ, or 1.56 TWh. It is possible to make these assumptions early on, and this is the result of the "Distance Act" [56]. Its relaxation llows this system to produce many times more energy.

**Figure 7.** Area available for the development of aeroenergy in the Pomerania Voivodeship (own study).

### *3.4. The Potential of Hydropower in the Pomerania Voivodeship*

The Pomerania region lies on the outskirts of two rivers—the Odra and the Vistula. As part of the Vistula River, which covers 86% of the province, it is possible to distinguish two hydrographic systems—Kashubian and Delta. According to Energy Regulatory Office data [78], there are 108 hydropower plants in the Pomerania Voivodeship, with a capacity of 34 MW. Considering that g = 9.81 m/s<sup>2</sup> and ρ = 1000 kg/m<sup>3</sup> and then = 0.85, we obtain:

$$\mathbf{P} = \theta.81 \cdot \theta \cdot \mathbf{H} \cdot \mathbf{\eta} \tag{11}$$

where:

—the capacity of a water turbine, or the volume of a stream of water flowing through the turbine within 1 s (m3/s);

H—head (m);

—the efficiency of the water turbine, the gear, and the generator (Korolewski and Ligocki 2004). Assuming efficiency at the level of 85%, we obtain the following model:

$$P = 8.34 \cdot \text{H} \cdot \text{\textdegree} \tag{12}$$

Assuming that the electronics will be able to operate for 6000 h/year at full power, i.e., 21,600,000 s/year, the annual amount of electricity from a given hydroelectric power plant Eel, for the output year (after conversion Wh to MWh), can be calculated as follows [4]:

$$\mathbf{E}\_{\mathbf{k}} = 2\mathbf{1}.\mathbf{6} \cdot \mathbf{P} \tag{13}$$

In the Pomerania Voivodeship, there are a number of facilities that can be used to produce electricity. These provide equally inexhaustible levels of water, serving in the past to fulfil energy targets, as well as for the identification of objects present in water during land reclamation. Based on the Equation (13) and data of the National Water Management Board on the levels of leveling and flooding (clearer, overflows) of water on the general furnaces, the theoretical power of electric and electric water, which can be calculated, is calculated.

In the Pomerania Voivodeship, the number of existing dams is:

• 154 dams on which a small hydropower plant (SHP) with a capacity of less than 5 kW can be placed;


**Figure 8.** The location of the dams and the power of small hydroenergy plants that can be built in the Pomerania Voivodeship (own study from [95]).

The total theoretical electric power of all dams is 40.1 MW. This potential can, of course, be increased by building new water dams.

### *3.5. Solar Energy in the Pomerania Voivodeship*
