**3. Results and discussion**

By comparing the methods, we can find that the calculation after partial substitution yields the same results for each year. This is due to the default efficiency, which is based on certain default values. Since we get the same PEF for the electricity mixture in all years, we cannot see changes in individual years. It is also impossible to predict what will happen to the factor in the coming years. We can see that the factor is 2.78, which represents a higher value than the predicted factor for Slovenia, which is 2.5 [21].

In the case of the physical energy method, we can better categorize individual years, and from the calculations, we see the PEF fluctuation. Physical energy method assumes energy conversion efficiency of 100% for renewable sources (produced electricity equals primary energy). The highest value of the factor occurred in 2003, while the lowest value amounted to 2.23 in 2016. The reason for such a change in the last year is in the increased production of electricity from renewable sources.

In the last method proposed by the standard SIST EN 15603, which computes two factors, we can see that in the case of the total factor, the value is higher than the average PEF, which takes into account only the nonrenewable part of energy. This is the case for renewable energy sources where PEF values are lower by threefold in comparison to nonrenewable energy sources. What is logical is that we do not consume any energy for the generation of hydro, wind, and solar energy. Likewise, we can also notice here that both factors are the highest in 2003, while they are the lowest in 2014. The reason for this is that the share of produced electricity from fossil fuels is the lowest, and the share of water energy is the highest, which means that due to the low share of energy from fossil fuels and high energy from renewable energy, the factor of PE has decreased.

#### **3.1 Forecast of electricity generation and impact on PEF**

By analyzing statistical data and calculating the PEF, we can predict the change of PEF for the electricity mix of Slovenia. The total production of electricity for the coming years and the annual growth of production were calculated by adding the individual quantities of electricity that were calculated by linear regression for each source separately. This means that we added the predicted production of electricity from nuclear power, fossil fuels, hydroelectric power, wind energy, and solar energy. With this simple linear regression, we predicted the amount of energy produced from different sources and how it affects the PEF. The predictions were made for 2020, 2030, and 2040 (**Table 7**). The share of individual sources and the total share of renewables are shown in **Table 8**.

In **Table 8**, we see that the nuclear energy share will decrease over time as well as for fossil fuels, whose share will decrease by more than 5% by 2040. In the case of hydro energy, the share will increase by just over 7%. Wind energy already

**75**

*2020.*

**Table 9.**

by almost 15%.

**Table 7.**

**Table 8.**

PEF are listed in **Table 10**.

**Production [GWh]**

*Primary Energy Factor for Electricity Mix: The Case of Slovenia*

represents a very small share in electricity, so in the future it is not expected to grow significantly. The share of solar energy will also increase; by 2040, we can expect an almost 5% increase. As we can see, Slovenia already generates a large share of electricity from renewable sources; by 2040, we can expect that this share will grow

**Year 2017 2020 2030 2040** Nuclear 38.5 35.0 33.9 33.0 Fossil 34.36 31.8 28.5 25.7 Hydro 25.37 30.4 32.9 35.0 Wind 0.04 0.1 0.1 0.1 Solar 1.73 2.7 4.6 6.2 Total share of renewables 27.1 33.2 37.6 41.3

**Year 2017 2020 2030 2040** Nuclear 6285 6147 6574 7001 Fossil 5610 5592 5524 5455 Hydro 4141 5350 6384 7418 Wind 6 9 14 25 Solar 283 475 894 1312 Total 16,325 17,574 19,392 21,211

For the partial substitution method, we used the same production efficiency as given in **Table 3**. The only difference is that in this case we carry out the calculation for 2020, 2030, and 2040. In **Table 9** we see an example of the calculation for 2020,

The PEF calculated according to the method of partial substitution method does not change over the years. The reason why the factor remains the same is that the

> **Useful energy [GWh]**

**Primary energy [GWh]**

**PEF**

For the physical energy method, we used the same production efficiency as in Chapter 2.2. The predictions for 2020, 2030, and 2040 have been recalculated, taking into account the energy production predicted by linear regression. In this method we also considered 10% network losses in the network. The forecasts of the

Total 17,574 1757.4 15,816 43,934 2.78

*Calculation of predicted PEF by partial substitution method for the production of electricity in Slovenia in* 

where we used the previously predicted quantity of produced electricity.

method assumes the same production efficiency for all energy sources.

**Network loss [GWh]**

**3.2 Forecast of the primary energy factor for Slovenia**

*Prediction of energy shares in the production of electricity.*

*DOI: http://dx.doi.org/10.5772/intechopen.84570*

*Forecast of total electricity production [GWh].*


#### *Primary Energy Factor for Electricity Mix: The Case of Slovenia DOI: http://dx.doi.org/10.5772/intechopen.84570*

#### **Table 7.**

*Energy Policy*

**3. Results and discussion**

Slovenia, which is 2.5 [21].

renewable energy, the factor of PE has decreased.

total share of renewables are shown in **Table 8**.

**3.1 Forecast of electricity generation and impact on PEF**

sources.

In **Table 6**, two PEFs for the electric mixture are calculated through the fractions of individual energies composing the electricity mix in Slovenia for 2017. We can see that the average PEF for nonrenewable is less than the total factor. The reason for this is that the default primary factors that take into account only the nonrenewable part of primary energy are lower than the total or total factor. The difference between the two average factors is almost 0.3, which is not negligible. As with previous methods, here again, the calculation was also performed for previous years,

with the same default factors. The results are shown in **Figure 3**.

By comparing the methods, we can find that the calculation after partial substitution yields the same results for each year. This is due to the default efficiency, which is based on certain default values. Since we get the same PEF for the electricity mixture in all years, we cannot see changes in individual years. It is also impossible to predict what will happen to the factor in the coming years. We can see that the factor is 2.78, which represents a higher value than the predicted factor for

In the case of the physical energy method, we can better categorize individual

In the last method proposed by the standard SIST EN 15603, which computes two factors, we can see that in the case of the total factor, the value is higher than the average PEF, which takes into account only the nonrenewable part of energy. This is the case for renewable energy sources where PEF values are lower by threefold in comparison to nonrenewable energy sources. What is logical is that we do not consume any energy for the generation of hydro, wind, and solar energy. Likewise, we can also notice here that both factors are the highest in 2003, while they are the lowest in 2014. The reason for this is that the share of produced electricity from fossil fuels is the lowest, and the share of water energy is the highest, which means that due to the low share of energy from fossil fuels and high energy from

By analyzing statistical data and calculating the PEF, we can predict the change of PEF for the electricity mix of Slovenia. The total production of electricity for the coming years and the annual growth of production were calculated by adding the individual quantities of electricity that were calculated by linear regression for each source separately. This means that we added the predicted production of electricity from nuclear power, fossil fuels, hydroelectric power, wind energy, and solar energy. With this simple linear regression, we predicted the amount of energy produced from different sources and how it affects the PEF. The predictions were made for 2020, 2030, and 2040 (**Table 7**). The share of individual sources and the

In **Table 8**, we see that the nuclear energy share will decrease over time as well as for fossil fuels, whose share will decrease by more than 5% by 2040. In the case of hydro energy, the share will increase by just over 7%. Wind energy already

years, and from the calculations, we see the PEF fluctuation. Physical energy method assumes energy conversion efficiency of 100% for renewable sources (produced electricity equals primary energy). The highest value of the factor occurred in 2003, while the lowest value amounted to 2.23 in 2016. The reason for such a change in the last year is in the increased production of electricity from renewable

**74**

*Forecast of total electricity production [GWh].*


#### **Table 8.**

*Prediction of energy shares in the production of electricity.*

represents a very small share in electricity, so in the future it is not expected to grow significantly. The share of solar energy will also increase; by 2040, we can expect an almost 5% increase. As we can see, Slovenia already generates a large share of electricity from renewable sources; by 2040, we can expect that this share will grow by almost 15%.

#### **3.2 Forecast of the primary energy factor for Slovenia**

For the partial substitution method, we used the same production efficiency as given in **Table 3**. The only difference is that in this case we carry out the calculation for 2020, 2030, and 2040. In **Table 9** we see an example of the calculation for 2020, where we used the previously predicted quantity of produced electricity.

The PEF calculated according to the method of partial substitution method does not change over the years. The reason why the factor remains the same is that the method assumes the same production efficiency for all energy sources.

For the physical energy method, we used the same production efficiency as in Chapter 2.2. The predictions for 2020, 2030, and 2040 have been recalculated, taking into account the energy production predicted by linear regression. In this method we also considered 10% network losses in the network. The forecasts of the PEF are listed in **Table 10**.


#### **Table 9.**

*Calculation of predicted PEF by partial substitution method for the production of electricity in Slovenia in 2020.*


#### **Table 10.**

*Forecast of the PEF for the electricity mix in Slovenia using the physical energy method.*

We can see that the PEF will decrease over time. This result is logical, since the share of renewable energy sources will increase substantially over time. Hence, the PEF is expected to decrease. For better transparency, the PEF calculated by the physical energy method is depicted along its forecast in **Figure 4**.

Calculation of PEF according to the standard SIST EN 15603 was carried out as described in Chapter 2.3. In this method we use the proportions of individual sources determined by linear regression. Two PEFs are proposed, namely, the average PEF-nonrenewable and average PEF-total. The PEFs for 2020 are given in **Table 11**. The average PEF for the electricity mix with predicted values is illustrated in **Figure 5**. It can be noticed that by 2040, the average PEF for nonrenewable energy will decrease to a value of 2.17, while the average PEF-total will be 2.58.

According to the conversion factors of PE, discrepancy between nonrenewable and total PEFs for the electricity mix can be significant. From **Figure 6**, we can see the annual progress of all the PEFs, calculated with all three evaluated methods, for electricity in Slovenia.

With the partial substitution method, we can see that the PEF for electricity does not change over the years, i.e., it remains 2.78. The reason for this lies in the assumption about the efficiency of production from renewable energy sources and nuclear energy, where 40% efficiency is taken into account. Furthermore, the same efficiency is also used for fossil fuels. Therefore, the efficiency of production from all primary sources is 40%. This is why we get the same PEF for all years. This means that according to this method, we do not get the correct representation of the PEF for the electricity mix, or the assumptions are not applicable for the case of Slovenia. In the event that Slovenia produced part of the electricity from biomass, whose production efficiency is estimated with 30% in this method, the PEF would be more volatile. However, Slovenia does not use biomass for the production of electricity; therefore, this method does not give us the useful values of the factor. We also notice that the factor 2.78 is quite high in terms of other methods.

**77**

**Figure 6.**

The other method used to determine the PEF for electricity is the physical energy method. With this method we evaluate the efficiency of production from renewable energy sources as 100%, while the default efficiency of nuclear power

*Comparison of the methods of calculating the PEF for the electricity mix in Slovenia.*

*Primary Energy Factor for Electricity Mix: The Case of Slovenia*

**2020 PEF**

**Nonrenewable Total Slovenia (average)**

Nuclear 2.8 2.8 34.98 0.98 0.98 Fossil 4.05 4.05 31.82 1.29 1.29 Hydro 0.5 1.5 30.45 0.15 0.46 Wind 0.5 1.5 0.05 0.00 0.00 Solar 0.5 1.5 2.70 0.01 0.04

*Forecast of the PEF for the electricity mix in Slovenia for 2020, using the reference values from the standard* 

*Average PEF for electricity mix according to the SIST EN 15603 method with predicted values.*

**Energy Share [%] Nonrenewable Total**

Sum 2.43 2.77

*DOI: http://dx.doi.org/10.5772/intechopen.84570*

**Table 11.**

**Figure 5.**

*SIST EN 15603.*

**Figure 4.** *PEF of electricity calculated according to the physical energy method.*

*Primary Energy Factor for Electricity Mix: The Case of Slovenia DOI: http://dx.doi.org/10.5772/intechopen.84570*


#### **Table 11.**

*Energy Policy*

**Table 10.**

electricity in Slovenia.

We can see that the PEF will decrease over time. This result is logical, since the share of renewable energy sources will increase substantially over time. Hence, the PEF is expected to decrease. For better transparency, the PEF calculated by the

**Year Production [GWh] Primary energy [GWh] PEF** 17,574 38,442 2.43 19,392 41,024 2.35 21,211 43,607 2.23

Calculation of PEF according to the standard SIST EN 15603 was carried out as described in Chapter 2.3. In this method we use the proportions of individual sources determined by linear regression. Two PEFs are proposed, namely, the average PEF-nonrenewable and average PEF-total. The PEFs for 2020 are given in **Table 11**. The average PEF for the electricity mix with predicted values is illustrated in **Figure 5**. It can be noticed that by 2040, the average PEF for nonrenewable energy will decrease to a value of 2.17, while the average PEF-total will be 2.58.

According to the conversion factors of PE, discrepancy between nonrenewable and total PEFs for the electricity mix can be significant. From **Figure 6**, we can see the annual progress of all the PEFs, calculated with all three evaluated methods, for

With the partial substitution method, we can see that the PEF for electricity does not change over the years, i.e., it remains 2.78. The reason for this lies in the assumption about the efficiency of production from renewable energy sources and nuclear energy, where 40% efficiency is taken into account. Furthermore, the same efficiency is also used for fossil fuels. Therefore, the efficiency of production from all primary sources is 40%. This is why we get the same PEF for all years. This means that according to this method, we do not get the correct representation of the PEF for the electricity mix, or the assumptions are not applicable for the case of Slovenia. In the event that Slovenia produced part of the electricity from biomass, whose production efficiency is estimated with 30% in this method, the PEF would be more volatile. However, Slovenia does not use biomass for the production of electricity; therefore, this method does not give us the useful values of the factor.

We also notice that the factor 2.78 is quite high in terms of other methods.

*PEF of electricity calculated according to the physical energy method.*

physical energy method is depicted along its forecast in **Figure 4**.

*Forecast of the PEF for the electricity mix in Slovenia using the physical energy method.*

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**Figure 4.**

*Forecast of the PEF for the electricity mix in Slovenia for 2020, using the reference values from the standard SIST EN 15603.*

**Figure 5.**

*Average PEF for electricity mix according to the SIST EN 15603 method with predicted values.*

#### **Figure 6.**

*Comparison of the methods of calculating the PEF for the electricity mix in Slovenia.*

The other method used to determine the PEF for electricity is the physical energy method. With this method we evaluate the efficiency of production from renewable energy sources as 100%, while the default efficiency of nuclear power generation and fossil fuel is 33 and 40%, respectively. The PEF calculated according to this method is very low, as shown in **Figure 4**. The reason is in the assumption that the efficiency of production from renewable sources is 100% and Slovenia has a large share of renewable sources in its electricity production, mainly from hydropower sources. In the previous analyses of individual years and forecasts, we also noticed that the share of renewable resources is increasing over time. For this reason, from **Figure 4** decreasing trend for the future is clear. This means that a PEF determined by this method will slowly decrease with respect to the increase in renewable energy sources in electricity generation.

With calculation according to the standard SIST EN 15603, we calculated two different primary energy factors: the average PEF for nonrenewables, which takes into account only the nonrenewable part of the energy of individual primary sources, and the PEF, which takes into account the total share of primary energies. We used the default values of the individual factors determined by the method for each primary source separately. We can see that the average PEF for nonrenewable energy is much lower than the total. The reason for this is that the default values of the factors that we use to calculate the nonrenewable and total factor are different. The greatest differences occur in renewable energy sources. This is because renewable energy sources have a very small share of nonrenewable energy. Therefore, the factors for calculating the individual PE sources are low in the case of hydropower, wind, and solar energy. When calculating the total factor, the factor value for these types of energy is 1.5. Moreover, a different calculation approach is used in this method, i.e., the PEF is calculated through the shares of individual energy sources in the total electricity.
