# NFV-Enabled Efficient Renewable and Non-Renewable Energy Management: Requirements and Algorithms
## 3 Adaptive Energy Managements: Requirements, Components, and Mechanisms
### Components of the NFV-Enabled Ecosystem and Proposed Energy Management Mechanisms
#### 3.3.2 Energy Consumers  
The ECs are the IoT infrastructures that demand energy to execute services (i.e., workloads, jobs, or applications). They have processing, networking (e.g., SDN compatible), and control (automation systems to activate or deactivate the consumption) capabilities. The ES manages the ECs through the EM. In the proposed energy management model, the ECs are characterized by their energy consumption. Subsequently, an energy demand referred in also as a service is characterized by: (i) an identifier \(k\), with \(k\in\{1,\cdots,N\}\); (ii) a starting time (\(T_{init}^{k}\)); (iii) a power demanded (\(P_{d}^{k}\)); and, (iv) a finite duration or lifetime (\(T_{d}^{k}\)). For simplicity, the management model assumes that \(P_{d}^{k}\) is invariant during \(T_{d}^{k}\). Besides, the calculations for energy use optimization consider the joint action of all \(N\) services, which demand a total power demanded equal to \(P_{D}\), a value that is equivalent to the sum of each service.  
Given that the execution of some services is more important than that of others in a realistic environment, the energy management model also considers the prioritization in the power supply by including a priority-level identifier \(l\), with \(l\in\{1,\ldots,L\}\), to each service. These priority levels can be defined in the contractual terms between the EC and the ES [15], and with this information, the EM can identify the services that cannot be processed if \(P_{ES}<P_{D}\). The ecosystem (EM) prioritizes the processing of the services with the highest priorities (i.e., the demands are processed in descending order, with \(l=1\) being the highest priority level). The \(P_{D}\) considering the prioritization level of demands can be expressed as:  
\[\forall k\in N,\forall l\in L:\,P_{D}=\sum_{k=1}^{N}\sum_{l=1}^{L}P_{d}^{k,l} \tag{4}\]  
The services, according to their priority level, are categorized as Critical Services (CS) and Non-Critical Services (NCS). The CS (i.e., services with \(l=1\)) cannot be shiftable in time, their execution is mandatory, and consequently, the system must always guarantee their energy provisioning. Some examples of CS are services (devices) used for disasters, emergencies, surgical interventions and human life support, and road safety for passengers and drivers. Instead, NCS (i.e., \(l\in\{2,\ldots,L\}\)) can be shifted in time, their execution is critical, and they may even not be executed if \(P_{ES}<P_{D}\). Some examples of NCS include entertainment systems, home air conditioning systems, services that are associated with cleaning (washing machines and dryers), and non-essential home automation system. The power demanded by the CS, the NCS, and the \(P_{D}\) is presented in Equations (5)-(7), respectively.  
\[P_{d}^{k,cs}=\sum_{k=1}^{N}P_{d}^{k,1} \tag{5}\] \[P_{d}^{k,ncs}=\sum_{k=1}^{N}\sum_{l=2}^{L}P_{d}^{k,l}\] (6) \[P_{D}=P_{d}^{k,cs}+P_{d}^{k,ncs} \tag{7}\]