Modeling the balanced development of the region in the transition to renewable energy and maintaining the carbon cycle in land use

. The article provides the author's model for assessing the level of sustainability in the development of a region due to an increase in the share of alternative energy sources and on the premise of maintaining a carbon balance. It was taken into account that the possibility of maintaining the carbon balance in the region is greatly influenced by agricultural activities and landscape features of the region. Thus, in some regions it is necessary to allocate additional areas of ecosystems with a special nature management regime to maintain the carbon cycle. The model generated was tested on the example of the regions of the Ural Federal District of the Russian Federation. It has been established that carbon dioxide emission from anthropogenically disturbed territories is present in four regions of the district: Sverdlovsk (17.9 million tons), Chelyabinsk (45.04 million tons), Kurgan (40.9 million tons) and Tyumen (13.03 million tons) regions. Thus, even if the share of renewable energy in the energy balance increases to 37-93%, and the general balance is achieved, the carbon cycle is still disrupted. In order to preserve it, additional inclusion of up to 8.5-57.4% of the region territories into the special nature management regime is required.


Introduction
The emerging imbalances in the regional system can lead the system far from its state of equilibrium due to the transformation of existing material and energy flows, which leads to a general degradation of the environment [1].Among the key causes of the imbalances is the activities of conventional energy using fossil fuels.
Thus, the transformation of matter in the course of the activities of the Russian power industry reaches a value of 2 billion tons, which is fully commensurate with natural geological processes [2].This situation is a major factor leading to an imbalance in the region system, and hence to the emergence of environmental problems in the regions [3].It is possible to these correct imbalances through replacing traditional energy using fossil fuels with renewable energy sources [4] since renewable energy uses material and energy flows already circulating in the biosphere [5].Thus, it does not transform them in the process of operation, which contributes to the regional social, environmental and economic system sustainability.
Previous studies of certain Russian regions revealed a high level of poor sustainability between natural and anthropogenic processes.It has been found that the transition to renewable energy sources is able to improve the overall balance of material and energy flows [2].However, a pattern was subsequently revealed that the features of land use in the regions, various natural conditions, may not allow for full observation of the carbon cycle, even with a full transition to renewable energy.This situation must be influenced, taking into account the different characteristics of the landscapes and agricultural activities of the regions.
A new model of balancing the region system will be required to manage this process, which will allow taking into account both the development of alternative energy sources in the region and the preservation of the carbon cycle in various territories.

Materials and methods
The study is based on the author's model, which allows predicting the sustainability level system of a region, with the assimilation (environmental) potential of the territory natural environment, and the possibilities for further development, subject to increased energy balance of renewable energy sources and the preservation carbon balance.
The system of the region in the model presented is a "triad" components.Flows of matter and energy move between the components affecting the biospheric metabolism.Thus, the system of the region consists of three large subsystems exchanging material and energy flows [6].Their management will consist of finding a balance between these flows, and the level of their intensity will provide the necessary information on the presence or absence of imbalances and their strength [7].This method is based on the "triad" analysis method proposed by G.B. Kleiner [8].
The task of establishing the "triad" balance consists in building the following function:  G = f(a,b,c) → 0, as a → ∞ (b,c) are fixed, and the same is for any other argument.
In order to build this function, the degree of relationship between the elements of the "triad" must be considered.
Figure 1 shows a cyclic diagram of interactions between the three components of the "triad": social (A), environmental (B) and economic (C).Indicators a, b, c characterize the intensity of interaction between the components of the "triad".The balanced development of the region is characterized by equal intensity of interaction between the components of the "triad", i.e. the equality of a=b=c.The emerging imbalances will be characterized by varying intensity of interaction between the components of the "triad".All possible ratios of indicators of the intensity of connections existing between the components of the "triad" may be represented as follows: , if sustainability is achieved, the sum of all relations S is equal to 6, and the indicator R is equal to 1. Otherwise, if R is less than or greater than 1, the system is poorly balanced.
It should be especially noted that it is the ratio between peaks B and C of the "triad" that is responsible for the balance in ecological development.Therefore, it is necessary to identify which parameters of the system should be used as peaks B and C of the "triad" for further modeling of the intensity of their interaction and determining the level of balance.
It is necessary to highlight the especially environmental peak of the "triad" -B t ecol.A single transition to the renewable energy sector is not able to ensure a balanced state of the regional system.A techno sphere using exclusively renewable energy is capable of destroying natural ecosystems, which will inevitably result in carbon imbalance [9].The process of maintaining this balance is largely influenced by the area's landscape features and existing land use activities [10].Thus, the model proposed characterizes the peak by two parameters: assimilation (environmental) potential of the territory (B t1 ecol. ) and balance of the regional carbon balance (B t2 ecol.).The assimilation (environmental) potential of a territory is determined based on the calculation of the maximum permissible environmental load, using indicators of the energy capacity of ecosystems established by V.G.Gorshkov in the biosphere biotic regulation theory [11,12].
The proposed model uses the indicator of energy intensity of regional industrial (economic) activity as С t econ , which additionally allows assessing the level of the overall environmental intensity of the industry.Using this approach, the value of production and consumption of electrical power in the area under assessment gains great importance.At the same time, it should be taken into account that if traditional fossil fuel energy creates significant imbalances in material and energy flows, alternative energy does not change them or have a significant impact on natural processes (Keiko at al., 2016).Thus, in order to model a change in the sustainability level system with the development of the alternative energy sector, the share of alternative energy must be subtracted from the total amount of energy consumed in the region.
The ecological balance of the development of the region was determined on the basis of the indicator obtained by the ratio of the peaks B t1 ecol.and С t econ.the presented model.
When assessing the carbon cycle balance, the ability of regional ecosystems to assimilate carbon dioxide must be first taken into account (B t2 ecol.).Features of regional agricultural activities and the peculiarities of ecosystems have a very significant impact on the observation of the carbon cycle.

Results
The model presented was tested on the example of the regions of the Ural Federal District (UrFD).The district (UrFD) includes 6 regions with a population of 12.3 million people.The area of the district is 1818.5 thousand sq.km.(10.5% of the area of Russia).In terms of natural environment, the territory of the district is very heterogeneous consisting of mountainous and plain parts.The plain part is swampy, with a large number of lakes.The flora in the northern regions is tundra and forest-tundra, while taiga (mainly dark coniferous and light coniferous forests) prevails in the southern regions, occasionally turning into forest-steppe.The slopes of the southern part of the mountain range houses areas of broadleaf (linden and oak) forests.In general, forests and shrubs occupy no more than a quarter of the territory.Agricultural lands are located in the south, in the steppe and forest-steppe areas.The industry of the regions of the Ural Federal District is of an industrial and raw material orientation.The largest share of the GRP (gross regional product) in the structure of the economy falls on the industry associated with the extraction of minerals.It is in the regions of the District that the country's largest oil and gas and metallurgical industrial complexes are located.
Further, the natural and industry features of the regions of the district were translated into quantitative indicators of the two of the peaks of the "triad" in the model.Information on characteristics of the regions was obtained from earlier studies by the authors.
The model presented allows predicting the sustainability development of the regions.To achieve sustainability, it is necessary to ensure that the ratio between the environmental carrying capacity of ecosystems and power of the techno sphere of the region is less than or equal to one.With a significant imbalance (where the ratio value is much greater than one), this is only possible with an increase in the share of renewable energy industry in the regional energy balance, since it does not change the material and energy flows of ecosystems, unlike traditional energy sources.
However, the transition to exclusively renewable energy sources does not automatically achieve balance, since carbon emissions from anthropogenically disturbed landscapes are possible.In the Ural Federal District, the indicated situation is observed in four regions: Chelyabinsk region (emission 45.04 million tons), Kurgan region (emission 40.9 million tons), Sverdlovsk region (emission 17.9 million tons), Tyumen region (13.03 million tons).
To achieve full carbon balance in these regions, the structure of land use must be altered, landscapes associated with carbon emissions reduced, and areas with a special nature management regime where it can be absorbed, increased.
Table1 presents the results of modeling the share of renewable energy sector in the regional energy balance and the areas of special nature management regime, upon reaching which, it will be possible to secure full observance of the carbon balance in the regions of the Ural Federal District.Thus, four regions of the Ural Federal District, where carbon emission from anthropogenically disturbed landscapes is observed, will require a significant increase in the areas of ecosystems (with a special nature management regime) in order to maintain carbon balance.The resulting calculation is influenced by such features of the regions as the state of territorial ecosystems and the level of development of agricultural activities and energy-intensive industries.In particular, the Chelyabinsk and Kurgan regions, with a high share of agricultural land and a relatively small area of forests, will require 49.1% and 57.4% of the region's area as the steppe unchanged ecosystems, which will consequently require fundamental changes in agricultural technologies, which is shown in figure 2.

Discussion
At this point, the general structure of the Ural Federal District is dominated by the anthropogenically modified ecosystems.Researchers can sometimes lose sight of the fact that although they do not absorb carbon dioxide, they themselves are a significant source of carbon imbalance.As a result, the carbon balance will still remain disturbed, and greenhouse gas emissions (in CO 2 -eq.) will continue even in a hypothetical scenario associated with the complete transition of the electric power industry to renewable sources, and provided that the balance is achieved in terms of energy indicators.
Thus, in a number of regions, carbon balance may only be achieved if anthropogenically disturbed territories are reduced and the areas of ecosystems capable of efficiently absorbing carbon are increased.It should be emphasized that the increase in effective carbon-absorbing territories in the Kurgan, Chelyabinsk and Tyumen regions may occur not so much due to forest landscapes, but primarily due to the restoration of natural steppes which are currently almost completely replaced with cultural landscapes.It is practically impossible to convert the territories to areas with a special nature management status occupied by residential infrastructure objects; it is presumably possible to return some territories occupied by agricultural activities to the state of natural steppes in order to achieve regional carbon balance.However, it should be recognized that a radical transformation of agricultural production and a sharp increase in its intensity per unit area will be required.

Conclusions
As part of the study, a new model for the system sustainability of a region was formulated, taking into account the preservation of the carbon balance.In its essence, the model is based on the analysis of the interactions between the components of the system.The model itself is presented as a triad components.The balance of the region, provided that the carbon balance is maintained, is determined by the interaction between of the two peaks of the triad.The environmental peak is determined by two parameters: the assimilation potential of the region in terms of the energy capacity of ecosystems and the ability of regional ecosystems to assimilate carbon dioxide.The economic peak is characterized by the amount of energy consumed in industry activities.
As a result of the study and using the presented model, the following data on the sustainability level in the regions of the Ural Federal District were obtained.Achieving sustainability will require an increase in the share of alternative energy in the regional energy balance to 37-93% (46% on average in the Ural Federal District).At the same time, carbon dioxide emissions from anthropogenically disturbed territories will still remain in four regions of the district: Sverdlovsk (17.9 million tons), Chelyabinsk (45.04 million tons), Kurgan (40.9 million tons) and Tyumen (13.03 million tons) regions.For these regions to achieve carbon balance, even with the transition to renewable energy sources, significant changes in agricultural land use patterns will be required.
a, a) = 1 for any a > 0. And the same is for any other element. The function G = f(a,b,c) is symmetric, i.e. does not change its values in any permutation of the arguments.

Fig. 1 .
Fig. 1.Scheme for modelling the balanced development of the region.

.
When sustainability is achieved, all relationships become equal to 1.If the balance indicator of the region R is equal to 1, the system are to be recognized as balanced.The R indicator is calculated using the following formula:

Fig. 2 .
Fig. 2. Emission/absorption of carbon dioxide by the ecosystems of the regions of the Ural Federal District.

Table 1 .
Indicators of achieving sustainability in the regions of the Urals Federal District, provided that the carbon balance is maintained.