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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Multisectoral energy system with oemof
General description
Step1:  Import input data
Step2:  Add entities to energy system
Step3:  Optimize energy system and plot results
Step4:  Adding the gas sector
In order to add a gas power plant, a gas ressource bus is needed. The gas power plant connects the gas and electricity busses and thereby couples the gas and electricity sector.
Step5:  Adding the heat sector
The heat sector is added and coupled to the electricity sector similarly to the gas sector. The same component, the LinearTransformer, is used to couple the two sectors. Only through its parametrisation it becomes a heater rod or a heat pump.
Step6:  Adding a heat pump
There are different ways to model a heat pump. Here the approach of precalculating a COP and using this as a conversion factor for the LinearTransformer is used. Another approach is to use the LinearN1Transformer that has two inputs - electricity and heat from a heat source. See the solph example "simple_dispatch".
Step7:  Adding a combined heat and power plant
The combined heat and power plant couples the gas, electricity and heat sector.
Step8:  Adding the mobility sector
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Python Code:
from oemof.solph import EnergySystem
import pandas as pd
# initialize energy system
energysystem = EnergySystem(timeindex=pd.date_range('1/1/2016', 
                                                    periods=168, 
                                                    freq='H'))
Explanation: Multisectoral energy system with oemof
General description:
The jupyter notebook gives a simple example of how to couple the sectors power, heat and mobility.
Installation requirements:
This example requires oemof 0.1.4 and jupyter. Install by:
pip install oemof==0.1.4 jupyter
Create a simple energy system
Initialize energy system
End of explanation
# import example data with scaled demands and feedin timeseries of renewables 
# as dataframe
data = pd.read_csv("data/example_data.csv", sep=",")
#print(data.demand_el[0:10])
#print(data.keys())
Explanation: Import input data
End of explanation
from oemof.solph import Bus, Flow, Sink, Source, LinearTransformer
### BUS
# create electricity bus
b_el = Bus(label="b_el")
# add excess sink to help avoid infeasible problems
Sink(label="excess_el",
     inputs={b_el: Flow()})
Source(label="shortage_el",
       outputs={b_el: Flow(variable_costs=1000)})
### DEMAND
# add electricity demand
Sink(label="demand_el",
     inputs={b_el: Flow(nominal_value=85,
                        actual_value=data['demand_el'],
                        fixed=True)})
### SUPPLY
# add wind and pv feedin
Source(label="wind",
       outputs={b_el: Flow(actual_value=data['wind'],
                           nominal_value=60,
                           fixed=True)});
Source(label="pv",
       outputs={b_el: Flow(actual_value=data['pv'],
                           nominal_value=200,
                           fixed=True)});
Explanation: Add entities to energy system
End of explanation
from oemof.solph import OperationalModel
import oemof.outputlib
import matplotlib.pyplot as plt
def optimize(energysystem):
    
    ### optimize
    # create operational model
    om = OperationalModel(es=energysystem)
    # solve using the cbc solver
    om.solve(solver='cbc',
             solve_kwargs={'tee': False})
    # save LP-file
    om.write('sector_coupling.lp', io_options={'symbolic_solver_labels': True})
    # write back results from optimization object to energysystem
    om.results();
    
def plot(energysystem, bus_label, bus_type):
    # define colors
    cdict = {'wind': '#00bfff', 'pv': '#ffd700', 'pp_gas': '#8b1a1a',
             'pp_chp_extraction': '#838b8b', 'excess_el': '#8b7355',
             'shortage_el': '#000000', 'heater_rod': 'darkblue',
             'pp_chp': 'green', 'demand_el': 'lightgreen', 'demand_th': '#ce4aff', 
             'heat_pump': 'red', 'leaving_bev': 'darkred', 'bev_storage': 'orange'}
    
    # create multiindex dataframe with result values
    esplot = oemof.outputlib.DataFramePlot(energy_system=energysystem)
    # select input results of electrical bus (i.e. power delivered by plants)
    esplot.slice_unstacked(bus_label=bus_label, type=bus_type,
                           date_from='2016-01-03 00:00:00',
                           date_to='2016-01-06 00:00:00')
    # set colorlist for esplot
    colorlist = esplot.color_from_dict(cdict)
    
    # set plot attributes
    esplot.plot(color=colorlist, title="January 2016", stacked=True, width=1, 
                kind='bar')
    esplot.ax.set_ylabel('Power')
    esplot.ax.set_xlabel('Date')
    esplot.set_datetime_ticks(tick_distance=24, date_format='%d-%m')
    esplot.outside_legend(reverse=True)
    plt.show()
optimize(energysystem)
plot(energysystem, "b_el", "to_bus")
Explanation: Optimize energy system and plot results
End of explanation
# add gas bus
b_gas = Bus(label="b_gas",
            balanced=False)
# add gas power plant
LinearTransformer(label="pp_gas",
                  inputs={b_gas: Flow(summed_max_flow=200)},
                  outputs={b_el: Flow(nominal_value=40,
                                      variable_costs=40)},
                  conversion_factors={b_el: 0.50});
optimize(energysystem)
plot(energysystem, "b_el", "to_bus")
Explanation: Adding the gas sector
In order to add a gas power plant, a gas ressource bus is needed. The gas power plant connects the gas and electricity busses and thereby couples the gas and electricity sector.
End of explanation
# add heat bus
b_heat = Bus(label="b_heat",
             balanced=True)
# add heat demand
Sink(label="demand_th",
     inputs={b_heat: Flow(nominal_value=60,
                        actual_value=data['demand_th'],
                        fixed=True)})
# add heater rod
LinearTransformer(label="heater_rod",
                  inputs={b_el: Flow()},
                  outputs={b_heat: Flow(variable_costs=10)},
                  conversion_factors={b_heat: 0.98});
optimize(energysystem)
plot(energysystem, "b_heat", "to_bus")
Explanation: Adding the heat sector
The heat sector is added and coupled to the electricity sector similarly to the gas sector. The same component, the LinearTransformer, is used to couple the two sectors. Only through its parametrisation it becomes a heater rod or a heat pump.
End of explanation
# COP can be calculated beforehand, assuming the heat reservoir temperature 
# is infinite random timeseries for COP
import numpy as np
COP = np.random.uniform(low=3.0, high=5.0, size=(168,))
# add heater rod
#LinearTransformer(label="heater_rod",
#                  inputs={b_el: Flow()},
#                  outputs={b_heat: Flow(variable_costs=10)},
#                  conversion_factors={b_heat: 0.98});
# add heat pump
LinearTransformer(label="heat_pump",
                  inputs={b_el: Flow()},
                  outputs={b_heat: Flow(nominal_value=20,
                                        variable_costs=10)},
                  conversion_factors={b_heat: COP});
optimize(energysystem)
plot(energysystem, "b_heat", "to_bus")
Explanation: Adding a heat pump
There are different ways to model a heat pump. Here the approach of precalculating a COP and using this as a conversion factor for the LinearTransformer is used. Another approach is to use the LinearN1Transformer that has two inputs - electricity and heat from a heat source. See the solph example "simple_dispatch".
End of explanation
# add CHP with fixed ratio of heat and power (back-pressure turbine)
LinearTransformer(label='pp_chp',
                  inputs={b_gas: Flow()},
                  outputs={b_el: Flow(nominal_value=30,
                                      variable_costs=42),
                           b_heat: Flow(nominal_value=40)},
                  conversion_factors={b_el: 0.3,
                                      b_heat: 0.4});
from oemof.solph import VariableFractionTransformer
# add CHP with variable ratio of heat and power (extraction turbine)
VariableFractionTransformer(label='pp_chp_extraction',
                            inputs={b_gas: Flow()},
                            outputs={b_el: Flow(nominal_value=30,
                                                variable_costs=42),
                                     b_heat: Flow(nominal_value=40)},
                            conversion_factors={b_el: 0.3,
                                                b_heat: 0.4},
                            conversion_factor_single_flow={b_el: 0.5});
optimize(energysystem)
plot(energysystem, "b_el", "to_bus")
Explanation: Adding a combined heat and power plant
The combined heat and power plant couples the gas, electricity and heat sector.
End of explanation
from oemof.solph import Storage
charging_power = 20
bev_battery_cap = 50
# add mobility bus
b_bev = Bus(label="b_bev",
            balanced=True)
# add transformer to transport electricity from grid to mobility sector
LinearTransformer(label="transport_el_bev",
                  inputs={b_el: Flow()},
                  outputs={b_bev: Flow(variable_costs=10,
                                       nominal_value=charging_power,
                                       max=data['bev_charging_power'])},
                  conversion_factors={b_bev: 1.0})
# add BEV storage
Storage(label='bev_storage',
        inputs={b_bev: Flow()},
        outputs={b_bev: Flow()},
        nominal_capacity=bev_battery_cap,
        capacity_min=data['bev_cap_min'],
        capacity_max=data['bev_cap_max'],
        capacity_loss=0.00,
        initial_capacity=None,
        inflow_conversion_factor=1.0,
        outflow_conversion_factor=1.0,
        nominal_input_capacity_ratio=1.0,
        nominal_output_capacity_ratio=1.0,
        fixed_costs=35)
# add sink for leaving vehicles
Sink(label="leaving_bev",
     inputs={b_bev: Flow(nominal_value=bev_battery_cap,
                         actual_value=data['bev_sink'],
                         fixed=True)})
# add source for returning vehicles
Source(label="returning_bev",
       outputs={b_bev: Flow(nominal_value=bev_battery_cap,
                            actual_value=data['bev_source'],
                            fixed=True)});
optimize(energysystem)
plot(energysystem, "b_bev", "from_bus")
plot(energysystem, "b_el", "to_bus")
plot(energysystem, "b_el", "from_bus")
Explanation: Adding the mobility sector
End of explanation
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