Energy balance: Difference between revisions

Revision as of 13:48, 6 July 2015

This page is a knowledge crystal of subtype method. The page identifier is Op_en5141
Moderator:Jouni (see all)
This page is a stub. You may improve it into a full page.
Upload data {{#opasnet_base_link:Op_en5141}}

The energy calculation based on two core concepts

Energy production or source
Energy consumption

Question

How to calculate energy balances?

Answer

Press button to run the model. Get a free user account and edit the table below to change the model inputs. You may also copy the model to your own page for your own purposes. For examples, see e.g. Energy balance in Kuopio or Energy balance in Suzhou.

+ Show code - Hide code

library(OpasnetUtils)
library(ggplot2)

objects.latest("Op_en5141", code_name = "initiate")

N <- 10

balance <- Ovariable("balance", ddata = "Op_en5141.equations")

balance@data$Equation <- as.character(levels(balance@data$Equation)[balance@data$Equation]) # Change factor into character.
balance@data$Policy[balance@data$Policy == ""] <- NA # Prepare indices for fillna. This should be part of fillna.
balance@data$CHPcapacity[balance@data$CHPcapacity == ""] <- NA
balance@data <- fillna(balance@data, marginals = 1:2) # Fill empty slots in indices.

nonlinearity <- Ovariable("nonlinearity", ddata = "Op_en5141", subset = "Nonlinearity parameters")

directinput <- Ovariable("directinput", ddata = "Op_en5141", subset = "No modelled upstream variables")


eb <- EvalOutput(energy.balance) 

eb@marginal[colnames(eb@output) == "energy.balanceVar"] <- TRUE # This has to be done manually because CheckMarginals does not notice this as a marginal.
eb@marginal[colnames(eb@output) %in% nonlinearity@output$critIndex] <- FALSE # Nonlinear indices are demarginalised because only one of the two equations apply.

oprint(summary(eb))

ggplot(eb@output, aes_string(x = "energy.balanceVar", y = "energy.balanceResult", fill = "Policy")) + 
	geom_boxplot() +
	theme_grey(base_size = 24) + 
	theme(axis.text.x = element_text(angle = 90, hjust = 1))

Rationale

Input

Example table for making matrices from text format equations. CHPcapacity describes which of the piecewise linear equations should be used. Policy is a decision option that alters the outcome. Dummy is only for compatibility but it is not used.

Equations(GWh /a)
Obs	CHPcapacity	Policy	Equation	Dummy	Description
1		Biofuel	CHP renewable = CHP peat	1	Biofuel policy contains half biofuels, half peat
2		BAU	CHP renewable = 89.24	1
3			CHP peat + CHP renewable + CHP oil = CHP heat + CHP electricity	1
4			CHP peat = 90-98*CHP oil	1
5			CHP electricity = 0.689*CHP heat	1
6	CHP<1000		H heat = 0.08*CHP heat	1	Small heat plants reflect the total heat need
7	CHP>1000		CHP heat + CHP electricity = 1000	1	But production capacity of CHP may be overwhelmed, decoupling CHP heat and H heat.
8			H biogas + H oil = H heat	1
9			H oil = 18.973*H biogas	1
10			Bought electricity + CHP electricity = Cons electricity	1
11			CHP heat + H heat = Cons heat	1
12			Cons electricity = 900-1100	1
13			Cons heat = 900-1000	1

Example table to describe the details about nonlinear equations.

Nonlinearity parameters(GWh /a)
Obs	critVar	critIndex	rescol	critLocLow	critLocHigh	critValue
1	Cons heat	CHPcapacity	Result	CHP<1000	CHP>1000	1080

This table is fetched if there are no nonlinearities. Therefore, there is no need to copy it to the case study page.

No nonlinearities(GWh /a)
Obs	critVar	critIndex	rescol	critLocLow	critLocHigh	critValue
1

This table is fetched if there are no modelled upstream variables that would affect the equations.

No modelled upstream variables(-)
Obs	energybalanceVars	Result
1

Output

Output is an ovariable with column energy.balanceVar for the solved variables, a result column, and all other indices in the balance object used as input. This method has been used in several cases:

Data

Energy balances are described as input = output on a coarse level (called classes) where the structure is the same or similar to the OECD energy balance tables. If possible, this is described on the Energy balance method level and it is shared by all cities.
On more detailed (variable level in the matrix), the fraction of each variable of the total class are described separately. Fractions are city specific and they are described on city level in a separate table.
Based on the fraction table, detailed equations with variables are created. The format will be fraction * class total = variable.
The last fraction has zero degrees of freedom when the class total is given. However, it must have a variable and thus a row in the fraction table. The result for that variable is an empty cell (which results in NA).
Unlike in the previous version, all variables are given either as values or equations, and the user interface is not used for BAU. In contrast, user interface or decision table may be used to derive values for alternative scenarios.
To make this work, the city-specific fraction data must be defined as ovariable (so that it can be changed with a decision table), and also the energy balance method must be described asa ovariable. How are we going to make the two interplay, as we may want to have several cities?
- Define one city ovariable and evaluate energy balance with that. The ovariable has a generic name. Then, define a new city ovariable with the same name and re-evaluate the energy balance ovariable; this must be done so that the two cities are appended rather than replaced.
- city ovariables are appended first into a large fraction table, and then that is used to create the large energy balance matrix. ←--#: . This is clearly better. --Jouni 17:09, 21 February 2013 (EET) (type: truth; paradigms: science: defence)
The city-specific ovariable may have Iter and other indices. A separate matrix is created and solved for each unique combination of indices. This makes it possible to have a very flexible approach.
We should check if the energy balance matrix (see Matti's Excel) has city-specific equations. If possible, energy transformations are described as generic equations on the energy balance method.
Structure of OECD Energy balance tables (data):
- Fuel (given as observation columns in OECD table)
- Activity (row in OECD table)
- Description
Structure of the generic process table
- Equation,
- Col,
- Result,
- Description? ⇤--#: . This does not join up in a coherent way. --Jouni 17:09, 21 February 2013 (EET) (type: truth; paradigms: science: attack)
Columns for fraction table
- Class
- Item
- Result (fraction)
- Indices as needed

'Additional thoughts

Energy balance has these parts

General table that describes balances and conversions from ole fuel to another.
- Items and sums Are defined at generic level.
Data table that contains amounts from OECD table
Fraction table thAt describes how detailSs Are derived from sums.
if there Are additions to sta dard items, they descrided at city level in an addition table. It must have the struxture of the matrix table in long format.
can nonlinearities ne handled simply by indices separating two linear parts of nonlinear equations?

Old description

⇤--#: . What are other energy sources,i wish it should be specific,how about air transport,does it included in the energy balance calculation? --Sam0911 16:29, 10 February 2013 (EET) (type: truth; paradigms: science: attack)

Use a table where different fuel types are columns and different stocks, energy production processes, or consumption types are rows called Energy accounts (Ene.account for short). See also an example File:Energy supply in Europe.xls. All Ene.accounts and fuel types used are listed on Energy consumption classes.

**A part of a full energy balance sheet (ktoe/a).**
	Coal and peat	Crude oil	Petrochemical products	Electricity	Heat
Production and supply of primary energy
Production	129
Import		28	63
Export
Conversion of primary energy to use
Transfers
Electricity plants
CHP plants	-129	-28		61	96
Final energy consumption
Industry
Road transport			54
Heating				10	96
Other energy use			9	51

Energy balance can be considered as double-entry bookkeeping. The production and conversion are typically credit (i.e., where the energy comes from), while consumption is debit (i.e., where the energy is used). In a typical case, both credit and debit are marked positive on the energy balance sheet. However, there are activities that convert one fuel to another, so that the energy is moved from one column to another. In this case, credit (the source) is marked negative and debit (the target) is marked positive. This is because the production and conversion rows together should reflect how much energy is actually available for final consumption. In other words, the sum of production and conversion rows should equal the sum of the consumption rows in every column.

Because production + conversion = consumption, also production = consumption - conversion. These equations are used to derive the supply that is needed to fulfil the demand.

Fuel shares in generic processes

The table below contains connections of heating types and fuel usage in generic situations. There may be case-specific differences, which must be handled separately.

Fuel use in different heating types(-)
Obs	Heating	Burner	Fuel	Fraction	Description
1	Wood	Domestic	Wood	1
2	Oil	Domestic	Light oil	1
3	Gas	Domestic	Gas	1
4	Heating oil	Domestic	Light oil	1
5	Coal	Domestic	Coal	1
6	District	Undefined	Heat	1
7	Other sources	Domestic	Other sources	1
8	No energy source	Domestic	Other sources	1
9	Geothermal	Grid	Electricity	0.3	Geothermal does not sum up to 1 because more heat is produced than electricity consumed.
10	Centrifuge, hydro-extractor	Grid	Electricity	0.3	Not quite clear what this is but presumably a heat pump.
11	Solar heater/ collector	Grid	Electricity	0.1	Use only; life-cycle impacts omitted.
12	Electricity	Grid	Electricity	1

+ Show code - Hide code


# This is code Op_en5141/fuelSharesgeneric (only generic) on page [[Energy balance]].
library(OpasnetUtils)

fuelSharesgeneric <- Ovariable("fuelSharesgeneric", ddata = "Op_en5141", subset = "Fuel use in different heating types") # [[Energy balance]]
colnames(fuelSharesgeneric@data) <- gsub("[ \\.]", "_", colnames(fuelSharesgeneric@data))
#fuelSharesgeneric@data <- merge(fuelSharesgeneric@data, data.frame(Time = 1900:2080))

objects.store(fuelSharesgeneric)
cat("Object fuelSharesgeneric initiated!\n")

⇤--#: . District heating below moved out of the generic table. Should be put to city-specific pages. --Jouni (talk) 04:41, 12 June 2015 (UTC) (type: truth; paradigms: science: attack)

For guesstimates about Long-distance heating (which is used in Basel), see Climate change policies in Basel and de:IWB.

Calculations

Ovariable energyBalance below is used in Helsinki energy decision 2015. Prices of fuels in heat production are used as direct inputs in the optimising.

+ Show code - Hide code

## This code is  Op_en5141/energyBalance [[Energy balance]].
library(OpasnetUtils)

energyBalance <- Ovariable("energyBalance",
	dependencies = data.frame(
		Name = c(
			"energy", # Energy supply and demand in the system
			"nondynsupply", # Energy supply that is not optimised.
			"requiredName", # Fuel name for the energy type that is balanced for inputs and outputs.
			"fuelShares", # Shares of fuels for different heating types.
			"energyProcess", # Matrix showing inputs and outputs of the process of each plant.
			"fuelPrice", # Prices of fuels (by Time)
			"timelylimit", # Maximum energy supply in the given conditions at a particular time point
			"plantParameters" # Capacities and costs of running each plant
		),
		Ident = c(
			NA,
			NA,
			NA,
			NA,
			NA,
			"Op_en4151/fuelPrice",
			NA,
			NA
		)
	),
	formula = function(...) {
		
		# First, define the optimising function
		optfunction <- function(
			x, # Variables to optimise (activities of power plants).
			demand, # energy demand that must be met by supply (scalar)
			unitprice, # vector of prices per activity unit (by plant).
			unitRequired # vector of required energy produced per activity uniit (by plant).
		) {

			out <- sum(x * unitprice) + (demand - sum(x * unitRequired))^2 * 1E6
			
			return(out)
		}	

		# Simplify the energy demand and supply data and add index Fuel.
		ene <- unkeep(energy, prevresults = TRUE, sources = TRUE)
		ene <- oapply(ene, cols = c("Efficiency", "Renovation", "Building"), FUN = sum)
		ene <- oapply(ene * fuelShares, cols = "Heating", FUN = sum)

		if(!is.na(requiredName)) { # Energy balance is only done if requiredName is given

			# Non-dynamic energy supply and demand, which is not optimised.
			# It is multiplied by -1 because energy production consumes fuels.
			nondynen <- ene 
			nondynen@output <- nondynen@output[nondynen@output$Fuel != requiredName , ]
			nondynen <- nondynen * Ovariable(
				output = data.frame(Plant = "Unidentified", Result = -1), 
				marginal = c(TRUE, FALSE)
			)

			# Dynamic energy supply and demand, which IS optmised.
			dynen <- ene
			dynen@output <- dynen@output[dynen@output$Fuel == requiredName , ]
			dynen <- unkeep(dynen, cols = c("Fuel", "Burner"))

			# Operational costs per unit of activity. Fuel price is excluded and calculated elsewhere.
			operationCost <- plantParameters
			operationCost@output <- operationCost@output[operationCost@output$Parameter == "Operation cost" , ]
			operationCost <- unkeep(operationCost, cols = "Parameter")

			# Costs per unit of activity by plant. Fuel price included. Also revenues included.
			unitprice <- oapply(energyProcess * fuelPrice * -1, cols = "Fuel", FUN = sum) + operationCost
			colnames(unitprice@output)[colnames(unitprice@output) == "plantParametersResult"] <- "unitpriceResult"
			unitprice@output$unitpriceResult <- result(unitprice) # Save result into another column
			
			# Required energy produced per unit activity in each plant.
			unitRequired <- energyProcess
			unitRequired@output <- unitRequired@output[unitRequired@output$Fuel == requiredName , ]
			unitRequired <- unkeep(unitRequired, cols = "Fuel")
			
			# Temporary limit to energy supply due to time-related particular constraints.
			timlim <- (
				unkeep((timelylimit >= plantParameters) * plantParameters, prevresults = TRUE, sources = TRUE) +
				(timelylimit < plantParameters ) * timelylimit
			)
			timlim@output <- timlim@output[timlim@output$Parameter == "Max" , ]
			colnames(timlim@output)[colnames(timlim@output) == "plantParametersResult"] <- "timelylimitResult"
			timlim@output$timelylimitResult <- result(timlim) # Save result into another column
			timlim <- unkeep(timlim, cols = "Parameter")

			# Put all inputs into one ovariable and sort by Plant. Note: important outputs in columns
				# unitpriceResult, energyProcessResult, plantParametersResult, timelylimitResult and Result (dynen).
			temp <- unitprice * unitRequired * timlim * 
				unkeep(plantParameters, prevresults = TRUE, sources = TRUE) *
				0 + dynen

			indices <- unique(temp@output[temp@marginal & !colnames(temp@output) %in% c("Plant", "Burner", "Parameter")])

			out <- data.frame()
			
			for(i in 1:nrow(indices)) {
				temp2 <- merge(indices[i , , drop = FALSE], temp@output)
				temp2 <- temp2[order(temp2$Plant) , ]
				temp3 <- optim(
					par			= temp2[temp2$Parameter == "Min" , "plantParametersResult"],
					fn 			= optfunction, 
					lower 		= temp2[temp2$Parameter == "Min" , "plantParametersResult"],
					upper 		= temp2[temp2$Parameter == "Max" , "timelylimitResult"],
					unitprice 	= temp2[temp2$Parameter == "Min" , "unitpriceResult"],
					demand = temp2[temp2$Parameter == "Min" , "Result"][1], # from dynen
					unitRequired = temp2[temp2$Parameter == "Min" , "energyProcessResult"],
					method = "L-BFGS-B"
				)

				out <- rbind(out, data.frame(
					indices[i , , drop = TRUE],
					Plant = temp2$Plant[temp2$Parameter == "Min"],
					Result = temp3$par
				))
			}
			out <- Ovariable(output = out, marginal = c(rep(TRUE, ncol(out)-1), FALSE))
			out <- out * energyProcess # Optimised fuel usage
			out <- combine(out, nondynen) # Combine optimised and non-optimised energy demand
		} else {
			out <- ene # If optimisation is not done, take the simple version updated with fuelShares.
		}
		
		out <- unkeep(out, source = TRUE)
		marginals <- colnames(out@output)[out@marginal]
		out <- combine(out, nondynsupply) # Combine also non-dynamic energy supply
		
		# Fill in other indices (typically decisions) that are missing in nondynsupply
		marginals <- setdiff(marginals, colnames(nondynsupply@output)[nondynsupply@marginal])
		out@output <- fillna(out@output, marginals = match(marginals, colnames(out@output)))

		return(out)
	}
)

objects.store(energyBalance)
cat("Ovariable energyBalance stored.\n")

Stored objects below used by Energy balance in Kuopio.

+ Show code - Hide code

library(OpasnetUtils)
library(ggplot2)

solveMatrix <- function(equations, directinputtemp, N. = 0, verbose = FALSE, dbug = FALSE, ...) {
	if (N. == 0) N. <- openv$N
	N <- N.
	
	# Parse equations using regular expressions
	
	out <- gsub(" ", "", equations)
	out <- strsplit(out, "=")
	out <- lapply(out, strsplit, split = "+", fixed = TRUE)
	nterms <- rapply(out, length) # number of terms on each side of each equation
	signs <- rep(
			rep(c(1,-1), length(out)), # lhs - rhs = 0
			nterms
	)
	eqn <- factor(rep(rep(1:length(equations), each = 2), nterms)) # equation number
	out <- unlist(out)
	k <- rep(1, length(out))
	x <- out
	
	# Equation factors
	
	out <- strsplit(out, split = "*", fixed = TRUE)
	temp <- sapply(out, length) > 1
	
	for (i in (1:length(out))[temp]) {
		k[i] <- out[[i]][1]
		x[i] <- out[[i]][2]
	}
	
	# Constants
	
	temp <- substr(x, 1, 1) %in% 0:9 # is interpretable (probably)
	
	for (i in (1:length(out))[temp]) {
		k[i] <- x[i]
		x[i] <- "Constant"
	}
	
	# Direct input (substitutes for constants)
	
	if (nrow(directinputtemp) > 0) {
		l <- tapply(eqn, data.frame(eqn), length)
		di <- directinputtemp$energybalanceVars
		dires <- directinputtemp$directinputResult
		for (i in 1:length(di)) {
			temp <- eqn %in% names(l[l == 2]) & x %in% c("Constant", di[i])
			temp <- tapply(temp, eqn, sum)
			k[eqn %in% names(temp[temp == 2]) & x == "Constant"] <- dires[i]
		}
	}
	
	# Interpret possible distribution regular expressions (also converts text to numeric)
	
	out <- data.frame(eqn, x, signs, Result = k)
	out <- interpret(out, N = N)
	
	marg <- colnames(out)[colnames(out) %in% c("eqn", "x", "Iter")]
	
	out$k <- out$Result * out$signs
	
	# Separate constants and vars and make them into arrays
	
	temp <- out[out$x != "Constant", ]
	
	b <- out[out$x == "Constant", ]
	b <- tapply(b$k, b[marg[-2]], I)
	b[is.na(b)] <- 0
	
	temp <- tapply(temp$k, temp[marg], I)
	if ("Iter" %in% marg) {
		temp <- temp[,dimnames(temp)$x != "Constant",]
	} else {
		temp <- temp[,dimnames(temp)$x != "Constant"]
	}
	temp[is.na(temp)] <- 0
	
	if ("Iter" %in% marg) {
		out <- list()
		for (i in 1:N) {
			ret <- tryCatch(
				out[[i]] <- solve(temp[,,i], -b[,i]),
				error = function(...) return(NULL)
			)
			if (is.null(ret)) {
				print("Faulty matrix:")
				oprint(temp[,,i])
				stop(geterrmessage())
			}
		}
		out <- data.frame(
			energybalanceVars = names(unlist(out)), 
			Iter = rep(1:N, each = length(out[[1]])), 
			Result = unlist(out)
		)
	} else {
		ret <- tryCatch(
			out <- solve(temp, -b),
			error = function(...) return(NULL)
		)
		if (is.null(ret)) {
			print("Faulty matrix:")
			oprint(temp)
			stop(geterrmessage())
		}
		out <- data.frame(
			energybalanceVars = names(out),
			Result = out
		)
	}
	return(out)
}

energy.balance <- Ovariable( # NOTE! energy.balance requires that there exists object N that defines the number of iterations.
	name = "energy.balance",
	dependencies = data.frame(
		Name = c("balance", "nonlinearity", "directinput")
	),
	formula = function(...) {
		# Column Equation: change factor into character and demarginalise.
		balance@data$Equation <- as.character(balance@data$Equation)
		balance@marginal[colnames(balance@output) == "Equation"] <- FALSE
		
		# Take those indices that are not needed within solveMatrix and merge them to the balance from the directinput.
		directinputindex <- directinput@output[directinput@marginal]
		directinputindex <- directinputindex[!colnames(directinputindex) %in% c("Iter", "energybalanceVars")]
		
		indices <- unique(merge(balance@output[balance@marginal], directinputindex))
		
		# Look at each unique combination of index locations and solve the set of equations to each.
		
		out <- data.frame()
		for(k in 1:nrow(indices)) {
			
			equations <- merge(balance@output, indices[k , , drop = FALSE])
			
			directinputtemp <- merge(directinput@output[!is.na(result(directinput)),], indices[k, colnames(indices) != "Iter", drop = FALSE])
			directinputtemp <- directinputtemp[ , c("energybalanceVars", "directinputResult")]
			
			temp <- solveMatrix(as.character(equations[ , "Equation"]), directinputtemp, N. = N, ...)
			
			out <- rbind(out, merge(indices[k , , drop = FALSE], temp))
		}
		
		if(!(nonlinearity@output$critVar[1] == "" | is.na(nonlinearity@output$critVar[1]))) {
			
			# Go through the non-linear equations one at a time and find which values to use in which situation.
			
			for(i in 1:nrow(nonlinearity@output)) {
				
				critVar 	<- gsub(" ", "", as.character(nonlinearity@output$critVar[i]))
				critIndex 	<- as.character(nonlinearity@output$critIndex[i])
				rescol 		<- as.character(nonlinearity@output$rescol[i])
				critLocLow 	<- as.character(nonlinearity@output$critLocLow[i])
				critLocHigh	<- as.character(nonlinearity@output$critLocHigh[i])
				critValue 	<- result(nonlinearity)[i]
				
				marginal <- colnames(out) %in% c(colnames(balance@output)[balance@marginal], rescol, "Iter")
				
				choos <- out[out$energybalanceVars == critVar , marginal]
				choos <- choos[
					choos[critIndex] == critLocLow  & choos[rescol] <= critValue | 
						choos[critIndex] == critLocHigh & choos[rescol] >  critValue , 
					colnames(choos) != rescol # Remove result column 
				]
				
				out <- merge(out, choos)
			}
		}
		
		# Create the marginal: those from the parents and "energybalanceVars" but not nonlinear indices.
		outmarginal <- c(
			colnames(balance@output)[balance@marginal], 
			colnames(nonlinearity@output)[nonlinearity@marginal], 
			colnames(directinput@output)[directinput@marginal],
			"energybalanceVars"
		)
		outmarginal <- outmarginal[!outmarginal %in% nonlinearity@output$critIndex]
		outmarginal <- colnames(out) %in% outmarginal
		
		out <- new("ovariable", name = "energy.balance", output = out, marginal = outmarginal)
		
		return(out)
	}
)

objects.store(solveMatrix, energy.balance)

cat("Objects solveMatrix and energy.balance stored with code initiate.\n")

Model version that was used to run results for ISEE2013.

How to give uncertain parameters?

In equations, the content is interpreted only inside solveMatrix. Therefore, the typical approach where all unique index combinations are run one at a time does not work.
There should be an update in parameter interpretation for terms with one entry only. It can no longer be based on as.numeric, if distributions (=text) is allowed.
- If it starts with [a-z.] it is a variable name.
- If it starts with [0-9<\\-] it is a parameter value.
Instead of params[[i]] and [[vars]] vectors, a data.frame will be created with Result as the params column.
The data.frame is then interpreted with N = N. If parameters are probabilistic, Iter column will appear.
When all parameters have been interpreted, check if Iter exists.
If Iter exists, make a for loop for all values of Iter.
- Create a matrix from the parameters and solve.
- Rbind the result to a data.frame with Iter.
Return the output.

Old code with an input table with columns Equation, Col, Result, Description: [1]

References

Related files

In English
Assessment	Main page \| Helsinki energy decision options 2015
Helsinki data	Building stock in Helsinki \| Helsinki energy production \| Helsinki energy consumption \| Energy use of buildings \| Emission factors for burning processes \| Prices of fuels in heat production \| External cost
Models	Building model \| Energy balance \| Health impact assessment \| Economic impacts
Related assessments	Climate change policies in Helsinki \| Climate change policies and health in Kuopio \| Climate change policies in Basel
In Finnish
Yhteenveto	Helsingin energiapäätös 2015 \| Helsingin energiapäätöksen vaihtoehdot 2015 \| Helsingin energiapäätökseen liittyviä arvoja \| Helsingin energiapäätös 2015.pptx

Energy balance: Difference between revisions

Revision as of 13:48, 6 July 2015

Contents

Question

Answer

Rationale

Input

Output

Data

Old description

Fuel shares in generic processes

Calculations

See also

References

Related files

Navigation menu