**2. Methodology—GIS in RES Research**

GIS is increasingly used in RES sector research, including determining the potential of renewable energy. It allows you to calculate the potential of RES in a given region or country with grea<sup>t</sup> accuracy. Many papers have been published about using GIS for RES research over the last few years. The combination of a GIS and tools or multicriteria decision-making (MCDM) methods were used by Sánchez-Lozano et al. for performing an evaluation of the optimal placement of photovoltaic solar power plants in the area of Cartagena (Region of Murcia), Spain. An excellent analysis tool that allows for the creation of an extensive cartographic and alphanumeric database that will later be used by multi-criteria methodologies to solve problems simply and promote the use of multiple criteria is generated by the combination GIS-MCDM.

A suitable site selection for solar farms using GIS in the Karapinar region, Turkey was determined by Uyan [70]. The research showed that 15.38% (928.18 km2) of the study area had low suitability, 14.38% (867.83 km2) was moderately suitable, 15.98% (964.39 km2) as suitable, and 13.92% (840.07 km2) as the most suitable for solar farms.

Jahangiri et al. [71] showed that the eastern, central, and southwestern parts of Iran, the south of Oman, almost all parts of Iraq and Yemen, some northern and eastern parts of Egypt, the south of Jordan and Israel, as well as a small region in the southeast of Turkey are particularly ideal for setting up solar–wind power stations.

As far as Poland is concerned, there have not been many scientific studies so far in which the RES potential has been calculated using the GIS method. Sliz-Szkliniarz and Vogt [72] calculated the wind energy and biogas potential in the Kuyavian–Pomeranian Voivodeship. The application of a GIS-based approach showed that the Kuyavian–Pomeranian Voivodeship could be used for wind energy production to a grea<sup>t</sup> extent because the major technical potential remains untapped. By excluding the infrastructural and ecologicalrelated barriers, the area of almost 7500 km<sup>2</sup> remains suitable for wind collection. The potential for biogas production could meet the demand of 442 GWh of heat, 368 GWh of electricity, or 98 Mm<sup>3</sup> of methane, based on the assumed biogas feedstock mix [73].

Rozakis et al. [74] determined the straw potential of Poland using the GIS method. In the article, the actual production of straw was modeled on a scale of local districts as well as the needs of its local use and the possibility of the redistribution of excessive quantities to regions with a deficit of straw based on statistical data from the Polish Central Statistical Office. The results showed that the straw surplus should be used in the energy sector along with its geographical distribution. The detailed results at the municipal level indicated an excess capacity for biomass co-firing by the plant and areas to be fulfilled by additional biomass sources, such as biomass from energy plantations and forests.

The current 100% RES solution in Portugal is in favor of wind and hydro energy [67]. Wind power should be introduced by the use of large reversible or pumped hydropower plants and could be achieved by installing bigger wind turbines and storage systems. It has become possible to combine these storage systems with a transport system. Hydrogen and batteries could become a storage solution for large future systems once the technology progresses [75].

In the paper by [76], a 100% RES system for Macedonia in the year 2050 was designed. The results of the analyses showed that a 100% renewable energy system in Macedonia is possible. However, to achieve this goal, a large share of biomass, solar power, and wind power, as well as different storage technologies are needed. The analysis showed that at the moment, half of the renewable energy system seems much more likely than a 100% renewable energy system. With the additional energy efficiency steps, which will lead to a decrease in consumption, and with the installation of new generation capacities, the achievement of this goal is possible.

For this article, the technical potential of wind energy, solar energy, biomass, hydropower, and geothermal energy in the Greater Poland Voivodeship was calculated. The authors wanted to know if the RES technical potential, counted with the use of the GIS method, will allow for 100% coverage of the energy needs of the Greater Poland Voivodship. More attention was devoted to wind energy, because the distance law, which inhibited the development of wind energy in Poland, was in force. In analyzing the aforementioned articles, one can draw the conclusion that in almost every country, there are good conditions for the development of one, and most often several, renewable energy sectors. In addition, in Poland, many regions can cover their energy needs only from RES.

### **3. The Description of the Greater Poland Voivodeship**

The Greater Poland Voivodeship is located in the central-western part of Poland, with Pozna ´n being its capital city (Figure 2). The surface area of the voivodeship region is 29,826 km<sup>2</sup> (second largest in the country after the Mazowieckie Voivodeship), which is equal to 9.53% of Poland's area. The number of inhabitants of the Greater Poland Voivodeship is 3.47 million people. In terms of land management, the area of the Greater Poland Voivodeship is dominated by arable lands, which make up 65.4% of the area, whilst forests make up 25.7% [45].

The climate of the Greater Poland Voivodeship belongs to the temperate climate zone, where oceanic and continental influences converge. Despite a highly developed river network and an abundance of lakes, the voivodeship has limited water resources. This results from a low amount of atmospheric precipitation (the annual precipitation is from 480 mm to 600 mm), as well as insufficient investments into anthropogenic retention. The hydrological situation is worsened by open-cast brown coal mining. Water shortages in the Greater Poland Voivodeship are estimated at about 350 million m<sup>3</sup> [45].

The dominant types of soil in the Greater Poland Voivodeship include podzolic and rusty soils, which make up 60% of the area, as well as lessive and brown soils at 20%. The remaining types are mainly wetland soil (pseudogley soils, gley-podzolic soils, halfbog peat soils, alluvial soils). The Greater Poland Voivodeship farmers boast the highest agricultural output, both market and global, in the country. The region comes second in terms of global and market plant production and first in terms of global and market animal production. The agriculture of the Greater Poland Voivodeship takes a dominant

position when it comes to slaughter animal production, accounting for 22% of the whole country, of which pork production reaches nearly 26% whilst that of beef is 18.5%. The region also produces the highest amount of grain and sugar beet as well as a significant amount of rapeseed. In addition, the area covered by ground vegetable crops is higher than the domestic average (Figure 2) [45].

**Figure 2.** The physico-geographical map of the Greater Poland Voivodeship—watercourses and reservoirs (own study).

### **4. Wind Energy Potential in the Greater Poland Voivodeship**

In order to calculate the wind speed in the Greater Poland Voivodeship, the so-called inverse distance interpolation of data provided by the Institute of Meteorology and Water Management in Warsaw was carried out using the mean monthly wind speed and the mean monthly wind directions (8 directions) from years 1990–2014. The obtained mean wind speed values at the basic height, that is, 10 m (*vp*), were used to calculate mean wind speed values at the height of a rotor, that is, 100 m (*v1*), according to the following formula:

$$
\upsilon\_1 = \upsilon\_p (\hbar \mathcal{H}\_o)^k \tag{1}
$$

where *v1* is the mean wind speed at a height of 100 m (m/s), *vp* is the mean wind speed at a height of 10 m (m/s), *h* is the height of the rotor (in this case, 100 m), *ho* is the basic height (in this case, 10 m), *k* is the exponent, *k* = 0.14–0.30 [53], and was assumed to be 0.22.

Substituting

$$
\upsilon\_1 = \upsilon\_p (100/10)^{0.22} = 1.66 \text{ } \upsilon\_p \tag{2}
$$

The obtained results are displayed graphically in Figure 3. When analyzing Figure 3, it can be concluded that the best conditions for locating wind turbines in the Greater Poland Voivodeship region are in the southeast whilst the worst are in the west.

**Figure 3.** Average wind speed at a height of 100 m (own calculations).

According to the current regulations (the Wind Energy Investments Act, 2016), wind turbines in Poland must be placed away from other structures at a distance of 10 times (10*h*) their height (including the blades). Assuming the height is 140 m, the buffer will be 1400 m. Work is currently underway on the amendment of the RES Act; the "distance act" is to be amended, so a buffer of 700 m (5*h*) was also adopted in our calculations.

In the Greater Poland Voivodeship, the built-up area, along with the buffer zone of 700 m, reaches 16,655 km<sup>2</sup> (Figure 4) and 6609 km<sup>2</sup> for a buffer zone of 1400 m.

**Figure 4.** Area available for wind energy development—the built-up area with the buffer zones of 700 m and 1400 m in the Greater Poland Voivodeship (own calculations).

The area of the Greater Poland Voivodeship covered by flood plain areas is 6350 km<sup>2</sup> for a buffer zone of 700 m and 1260 km<sup>2</sup> for a buffer zone of 1400 m (Figure 5).

**Figure 5.** Area available for wind energy development—flood plains with the buffer zones of 700 m and 1400 m in the Greater Poland Voivodeship (own calculations).

The area of the Greater Poland Voivodeship covered by protected areas together with a buffer zone of 700 m is 12,910 km2, and with a buffer zone of 1400 m, is 10,397 km<sup>2</sup> (Figure 6).

**Figure 6.** Area available for wind energy development—protected areas with the buffer zones of 700 m and 1400 m in the Greater Poland Voivodeship (own calculations).

The area of the Greater Poland Voivodeship covered by forest with a buffer zone of 700 m is 12,012 km2, and it is 6394 km<sup>2</sup> for a buffer zone of 1400 m (Figure 7).

**Figure 7.** Area available for wind energy development—forest areas with the buffer zones of 700 m and 1400 m in the Greater Poland Voivodeship (own calculations).

In total, the available terrain for wind energy for a buffer zone of 700 m is 210 km<sup>2</sup> and for a buffer zone of 1400 m, only 2 km<sup>2</sup> (Figure 8).

**Figure 8.** Area available for wind energy development with the buffer zone of 700 m and 1400 m in the Greater Poland Voivodeship (own calculations).

The area of the Greater Poland Voivodeship that could be technically designated for the construction of wind turbines is 210 km<sup>2</sup> (buffer zone of 700 m). It was assumed that the operating wind turbines will have a diameter *r* = 50 m. In order to ensure that turbines do not interfere with one another, it was assumed that the distance between the turbines should be 5*<sup>r</sup>*, whilst in the direction towards the wind, it should be 8*<sup>r</sup>*. It was assumed that the wind turbines will be positioned in a network of rectangles, and each of the rectangles will have the dimensions 5*r* × 8*<sup>r</sup>*. The area taken up by one wind turbine is 100,000 m<sup>2</sup> (0.1 km2). Therefore, in an area of 377 km2, it is technically possible to position 2100 wind turbines. This means that the technical potential of the wind power sector in the Greater Poland Voivodeship is 4.2 GW. It was assumed that the amount of energy generated by one 2 MW wind turbine is 4.2 GWh. Thus, the total amount of electricity is 8,5 TWh, which is 65% of the electricity currently used in the Greater Poland Voivodeship [77].

### **5. Solar Energy Potential in the Greater Poland Voivodeship**

The annual solar radiation energy per area unit on a horizontal plane in Poland reaches between 950 and 1250 kWh/m2, whilst in the Greater Poland Voivodeship, it reaches about 1050–1150 kWh/m<sup>2</sup> (Figure 9). About 80% of this value is generated during the six months of the spring and summer seasons (April–September) [78,79]. It needs to be mentioned that solar operation in the summer is prolonged up to 16 h per 24-h period, whilst in winter, it shortens down to 8 h per 24-h period [79–81].

**Figure 9.** Annual solar radiation energy per area unit in the Greater Poland Voivodeship (own calculations).

The annual values of insolation in the Greater Poland Voivodeship vary from 1250 h in years with the highest cloud cover to 2000 h in the sunniest years. The long-term mean is 1600 h, which is similar to the long-term mean of insolation for all of Poland [77]. The analysis of variations in annual insolation carried out for Pozna ´n over a 25-year period, 1990–2014, indicates that the insolation value has been regularly increasing by 11 h/year, on average.

Photovoltaic panels can be installed in many places where they take up a relatively small space or where typical economic activity cannot be undertaken (e.g., around airports) [77]. In the Greater Poland Voivodeship, such places could be the roofs of buildings, closed waste site grounds, and post-industrial wasteland. In our investigation, we assumed that 5% of the roofs of buildings could be designated for photovoltaic panels and 2% of the roofs could be used for solar collectors. The gross covered area in the Greater Poland Voivodeship is 1648 km<sup>2</sup> (Figure 10) [77].

**Figure 10.** The gross covered area in the Greater Poland Voivodeship (own calculations).

In addition, if we assume that the roof area of a typical building is approximately equal to the gross covered area—that is, according to the Polish Standard [77], the area of the vertical projection of the building in a completion state, determined by projecting onto the area surface all of its external walls (in reality, it could be slightly larger, as roofs are often sloping and not horizontal)—then the available areas for photovoltaic panels and collectors in the Greater Poland Voivodeship are 82.4 km<sup>2</sup> and 33.0 km2, respectively. Based on the data [75], it can be assumed that from 1 m2, at least 120 kWh of electric power could be generated per year; thus, the total amount of electric power would be 9.84 TWh. The amount of heat obtained from 1 m<sup>2</sup> of a collector was assumed to be at the level of 650 kWh annually, which, combined with the whole area of the Greater Poland Voivodeship, amounts to 21.45 PJ.

### **6. The Biomass Energy Potential in the Greater Poland Voivodeship**

### *6.1. The Technical Potential of Waste Wood*

The Greater Poland Voivodeship is known as "the breadbasket of Poland". This Voivodeship region is where a significant part of food production takes place. Agricultural production generates considerable amounts of waste, which, together with forest waste, could be used to generate energy [82]. Forestation in the Greater Poland Voivodeship is 25.7% and lower than the average for Poland, which is 29.4% [73]. If we assume that 15% of wood obtained directly from forests could be used for energy purposes (parts of bark, slash, and more coarse waste wood generated during logging), then 450,000 m<sup>3</sup> of waste wood per year could be obtained in the Greater Poland Voivodeship.

Significant amounts of waste [83] and used timber would be at least the same as the amount of waste wood obtained from forests, that is, 450,000 m<sup>3</sup> (technical potential). In total, the amount of waste forest biomass for energy purposes can be estimated to be 900,000 m<sup>3</sup> per year. If we assume that 1 m<sup>3</sup> of wood weighs 600 kg, then the weight of waste wood would be 540,000 tons per year.

The area covered by orchards in the Greater Poland Voivodeship is 16,400 ha [82]. The timber from orchards is obtained from both felling and maintenance work. As a result of the felling of orchards, it is technically possible to obtain about 80 tons of biomass per 1 ha in the case of older plantations (about 30 years old) and about 60 tons/ha in the

case of modern dwarf plantations (about 15 years old). The amount of biomass created during maintenance work varies depending on the variety and age of the trees, from 4 to 10 tons/ha [64]. Assuming that due to the felling of orchards, 3.5 tons of biomass can be obtained per 1 ha per year, and that as a result of maintenance work, 7 tons of biomass is created per 1 ha per year, then it is possible to obtain 125,000 tons of waste biomass from orchards in the Greater Poland Voivodeship. In total, the waste wood in the Greater Poland Voivodeship amounts to 600,000 tons per year (technical potential).

### *6.2. The Technical Potential of Straw and Hay from Unused Meadows, Pastures, and Energy Crops*

In 2020, the Greater Poland Voivodeship produced about 770,000 tons of wheat straw, 310,000 tons of rye straw, 180,000 tons of barley straw, 330,000 tons of oats straw, and 50,000 tons of triticale straw [77]. The total amount of straw is 1,640,000 tons. Assuming that the technical potential of straw is 30%, then 492,000 tons of straw could be used for energy purposes. In the Greater Poland Voivodeship, there are 234,500 ha of meadows and 17,400 ha of pastures. The amount of hay harvested from meadows amounts to 4.9 tons per 1 ha/year, whilst from pastures, this amount is 3.6 tons per 1 ha/year [83]. Assuming that the technical potential of hay from meadows and pastures that could be used is 30%, then the amount of hay that could be used for energy purposes is 367,000 tons per year.

In the Greater Poland Voivodeship, there are 33,000 ha of fallow land and 36,000 ha of idle land [83]. These areas could be cultivated or reclaimed using energy crops. Our plant of choice is the common osier, which has been described in previous papers. This plant is used for both energy production and land reclamation. It could be assumed that it is viable to cultivate 50% of fallows and 25% of idle land; this means that there is an available area of 25,500 ha. The agriculture in the Greater Poland Voivodeship is at the highest level compared to other parts of the country. This is why, despite fallows and idle land being designated for cultivation, it can be assumed that the average biomass crop would be 20 tons of dry mass per 1 ha per year. This means that there would be a crop of about 510,000 tons of biomass per year.

### *6.3. The Technical Potential of Agricultural Biogas*

The technical potential of agricultural biogas in the Greater Poland Voivodeship was calculated, taking into consideration the conversion factor of livestock heads into livestock units (*LSU*; 500 kg) [84]. For cattle, the conversion rate is 0.8, for pigs—0.2, and for poultry—0.004. The mean amount of slurry per 1 *LSU* is 44.9 kg for cattle, 43.5 kg for pigs, and 26.8 kg for poultry. The number of heads was taken from the data of the Central Statistical Office [77]. The construction of biogas plants using slurry and/or poultry manure is technically and economically viable on farms with a livestock number of at least 100 heads of cattle, 500 heads of pigs, and 5000 heads of poultry. Thus, the technical potential of agricultural biogas from animal droppings in the Greater Poland Voivodeship should be estimated at 25% of the theoretical potential [83]. It was assumed that the production of biogas from 1 ton of cattle slurry was 50 m3, from pig slurry—55 m3, and from poultry manure—140 m3. The amount of biogas that could be obtained in the Voivodeship is 40 million m3.

In the Greater Poland Voivodeship, maize is grown for consumption purposes and as farm livestock fodder. After the maize knobs have been harvested for consumption purposes, what is left in the field are stalks and leaves, which could be used to produce biogas. It was assumed that it is technically possible to obtain biogas from 30% of sown plants, whilst straw constitutes 62% of the dry mass of the whole plant. In 2015, the area where maize was cultivated for its grain in the Greater Poland Voivodeship reached 3,288,000 ha [83]. Assuming the grain crop yielded 9 tons, whilst 1 ton of biomass can produce 90 m<sup>3</sup> of biogas, then the volume of biogas would be 1.3 billion m3. Due to the agricultural character of the Greater Poland Voivodeship, the opportunities to build agricultural biogas plants in the Greater Poland Voivodeship are grea<sup>t</sup> [85,86].

### *6.4. The Technical Potential of Biogas from Municipal Waste and Sewage Treatment Plants*

The amount of municipal waste generated in households and public-use buildings in the Greater Poland Voivodeship reaches 1.1 million tons, of which more than a half consists of biodegradable waste [87]. The technical potential of biogas from municipal waste can be estimated at the level of 40% of the theoretical potential. Assuming that 90 m<sup>3</sup> of biogas can be produced from 1 ton of waste, then it is possible to obtain nearly 20 million m<sup>3</sup> of biogas from municipal waste per year in the Greater Poland Voivodeship.

In the Greater Poland Voivodeship, 21.4 million m<sup>3</sup> of municipal sewage is treated [87]. Assuming that from 50% of effluents coming to the plant sludge can be obtained (sludge amounts to 1% of effluents) and that 1 m<sup>3</sup> of sludge produces 15 m<sup>3</sup> of biogas, then 1.6 million m<sup>3</sup> of biogas could be generated in the Voivodeship.

### *6.5. The Total Technical Potential of Bioenergy in the Voivodeship*

The Greater Poland Voivodeship has a very high potential to produce biomass for energy purposes. Table 1 shows the amounts of electric power and heat (in cogeneration) that could be produced from solid biomass. In total, it comes to about 25.6 PJ, which includes 2837 GWh of electric power and 12.8 PJ of heat (Table 1). The development of biomass-based energy generation would contribute a few hundred new work places in agriculture, the transport industry, companies dealing with biomass processing, such as briquette and pellet production, and eventually, in new boiler plants and heat and power stations.

**Table 1.** Electricity and heat production from solid biomass in the Greater Poland Voivodeship (own calculations).


Table 2 demonstrates the amounts of electric power and heat (in cogeneration) that could be obtained from biogas in the Greater Poland Voivodeship. In total, it reaches about 23.8 PJ, which includes 3.1 GWh of electric power and 12.6 TJ of heat (Table 2). In the Greater Poland Voivodeship, about 6 TWh of electric power could be obtained from solid waste biomass and biogas, which is nearly equivalent to 50% of the currently used energy [71]. On the other hand, the amount of heat that could be generated is 25.4 PJ, which amounts to 88% of the currently used heat.

**Table 2.** Electric power and heat production from biogas in the Greater Poland Voivodeship (own calculations).


### **7. The Water Energy Potential in the Greater Poland Voivodeship**

Until recently, mills and small hydropower plants could be frequently sighted in the Greater Poland Voivodeship. Apart from energy generation, they had been responsible for water retention for a few hundred years [88]. The drainage system had been closely linked, in a unique symbiosis one could say, to barrages [89]. Unfortunately, after World War II, most of the small hydropower stations fell into decline. In recent years, however, there has been a growing interest among investors in the hydropower sector in the Greater Poland Voivodeship [89–92].

Calculations of the technical potential of hydropower in the Greater Poland Voivodship with the use of already existing damming facilities were carried out. In river water power plants, electricity is obtained from kinetic energy, and especially from potential energy. Assuming the water density ρ = 1000 kg/m<sup>3</sup> and an efficiency of 85%, a formula [92,93] can be obtained, as follows:

$$P = 8.34 \Theta \cdot H \tag{3}$$

where *P* is the hydroelectric power (MW), Θ is the flow (m3/s), and *H* is the spades (height).

Assuming that the full power plant will operate 6000 h a year, the amount of energy from the *Ek* hydroelectric power plant will be as follows:

$$E\_k = 21.6 \cdot P \tag{4}$$

The data Θ and *H* were obtained from the National Water Management Board [66].

Figure 11 was created using the data provided by the Geodesic and Cartographic Documentation Centre [94]. Within the area of the Voivodeship, there are 1229 hydrotechnical structures—10 dams, 11 sluice locks, and 1208 weirs.

**Figure 11.** Hydrotechnical structures in the Greater Poland Voivodeship (own calculations).

It can be assumed that at least half of all the hydrotechnical structures in the Greater Poland Voivodeship could be used to generate electric power. If the same supposition as above was followed, then the potential would be a total of 123 MW, whilst the power generation would reach 615 GWh. Clean water is becoming a rarity in the Greater Poland Voivodeship. Thus, more care has been given to its purification in recent years; some of the sewage treatment plants could be used to generate electricity, the way it is already happening in Minsk (Belarus) [92].

In the Greater Poland Voivodeship, there are 425 sewage treatment plants [87]. As already mentioned, some of them could be used to generate electric power—there must be an adequate difference between the water levels and the amount of treated water. It can be assumed that from a technical standpoint, hydropower plants need to be erected at the sewage treatment plants with a flow of at least 1 million m<sup>3</sup> per year; 32 facilities meet this criterion (Figure 12). As an estimate, each of these could produce about 400–700 MWh of electric power. In total, this would provide about 8–12 GWh. It may not be a huge amount, but the main purpose of treating sewage is met anyway and electricity generation would just be a by-product.

**Figure 12.** Location of sewage treatment plants with a minimum capacity of 1 million m<sup>3</sup> per year (own calculations).

### **8. The Geothermal Energy Potential in the Greater Poland Voivodeship**

In the Greater Poland Voivodeship, the density of the terrestrial heat flow varies from 70 to 100 mW/m<sup>2</sup> (Figure 13) [95,96]. We know this is a result of a high number of exploratory bore holes, which were created after World War II, mainly during exploration for oil and natural gas resources. Using already existing bore holes results in significantly lower investment costs in the geothermal energy sector [95,96].

The data from the Central Geological Database [97] were used to create Figure 14, which shows bore holes of a minimum depth of 500 m in the Greater Poland Voivodeship.

The Greater Poland Voivodeship has good conditions not only for heat generation but also for electricity production [98]. In our study, it was assumed that binary geothermal heat and power plants could be implemented; their parameters are collated in Table 3. The construction of four binary heat and power plants will facilitate the production of 65.65 TJ of heat and 8.55 GWh of electric power per year. Medical and tourist centers are to be built next to the geothermal plants. For example, on the Island of Pociejewo in Konin, the geothermal water reaches a temperature of 97 ◦C and mineralization of 70 g/dm<sup>3</sup> at a depth of 2600 m. According to the initial physico-chemical investigation, this is a highly mineralized sodium chloride type of water, which contains large amounts of chloride, sodium, magnesium, and calcium ions as well as many microelements. It meets all the parameters of medicinal water. The architectural development plan of the island in Konin contains the geothermal plant Pociejewo, "The Ecological Town Salon", including a complex of 15, mainly indoor, swimming pools, 50 health and wellness salons, an exclusive hotel, and an indoor sports hall [99].

**Figure 13.** The map of terrestrial heat flow density for the Greater Poland Voivodeship in comparison to the whole of Poland (own study from [95,96]).

**Figure 14.** The bore holes of a minimum depth of 500 m in the Greater Poland Voivodeship (own study from [97]).


**Table 3.** Parameters of binary geothermal heat and power plants in the Greater Poland Voivodeship (net power value, taking into account own energy usage and loss) [98].

### **9. Total Technical Potential of the Renewable Energy in the Greater Poland Voivodeship**

The implementation of the goal set in the article allowed for the designation of the technical potential of the renewable energy sector in the Greater Poland Voivodeship using GIS methods. The obtained results indicate that the amount of available electricity and heat is higher than the energy demand of the Voivodeship (Table 4). As for electric power, it is possible to generate 23.34 TWh, which is 1.8 times more than the demand. As for heat, it is about 47 PJ, which is 1.6 times more than the demand. A surplus of energy could be sent to other voivodeship regions. In addition, our accurate calculations show that it is possible to produce 100% RES in other regions in Poland. This means that the Greater Poland Voivodeship may be energy independent in the future, where both electricity and heat would come entirely from renewable energy sources.

**Table 4.** Technical potential of RES in the Greater Poland Voivodeship (own calculations).


Source: own calculations.

This is an important argumen<sup>t</sup> in the further process of introducing just and bottom-up initiatives that would enable the regions coal-based energy transformation. Additionally, the development of RES contributes to increasing the energy security of the society and economy, which are powered by a network of smaller and safer power plants, and leads to stronger local communities.
