Is it possible to insert a CHP running on bio oil in HOMER, which contributes to the renewable fraction? Yes, it is possible. You should add a generator that uses a biofuel (like "biogas" for example). You can define your own biofuel in the library view. Go to fuels, select a built-in fuel, and click "Copy". Be sure to select the option "Bio Fuel

How does HOMER calculate the amount of waste heat from the generators? HOMER does report the quantity of excess electricity that serves the thermal load. That appears on the Thermal tab of the Simulation Results window. But it does not report the cost savings resulting from the application of the excess electricity to the thermal load. To de

What does capacity factor in the Gen tab of the “Simulation Results” output refer to? HOMER calculates the generator capacity factor by dividing the actual annual generator energy production by its maximum possible annual energy production.

HOMER has a default 'Carbon content' of 88 (% by mass) for diesel. The petrol company gave me the following spec. on their carbon content: "Carbon content as determined by carbon residue test is <0.1 wt%". Why such a large discrepancy? Is HOMER asking for a different parameter than what I got from the petrol company? Good question. Yes,

Can you tell me how HOMER calculates the efficiency of the diesel gensets? The Fuel tab of the Generator Inputs window lets you enter the fuel curve parameters, which define the graph of fuel consumption versus electric power output. The fuel curve calculator helps you calculate those parameters when you have the kind of fuel consumption data

Could you confirm the operation and maintenance figures for varying sized generators? The best data I have on diesel O&M cost come from Alaska, where labour is expensive and the climate is harsh so I think of them as the high end of the possible range: So the O&M costs for the 400 kW to 800 kW range are on the order of $14/hr. That

The diesel O&M cost is a critical factor in HOMER Pro analyses, and we know frustratingly little about it. For diesel generators, we typically assume an O&M cost of about 2 US cents per kWh at rated output. That would be $1/hr for a 50-kW diesel generator. HOMER assumes that the O&M cost per hour is independent of the power output, s

When calculating the expected life of the generator, HOMER Pro divides the generator life in operating hours by the number of hours the generator operates per year. In the aforementioned example, the generator happened to operate 8760 hours per year, but that is not necessarily the case. If HOMER Pro is reporting that the generator with the 87,60

By "no-load fuel cost" I assume you mean "Fixed generation cost". Is this value set by the Fuel consumption data in the Fuel curve calculator, specifically, the fuel consumption at 0 kW? Is this cost always incurred, even when the generator is not running (one would think the generator is off and not consuming fuel at 0 kW)? If my Fuel consumption

Can we simulate the DC/DC Converter between Fuel cell and DC Bus with 90% efficiency? HOMER's will not explicitly model the DC/DC converter, but you can account for the losses that occur in the converter by adjusting the fuel curve of the fuel cell. Just divide the fuel curve slope and intercept by 0.9. That way, the "fuel cell" component in

How can I use the fuel cell option? A fuel cell is a DC generator, so if you want to model a fuel cell, add a generator and make it DC. If you want the fuel cell to consume stored hydrogen generated by an electrolyzer, add an electrolyzer and a hydrogen tank, and specify the fuel cell's fuel as "Stored hydrogen". If you want the fuel cell to

What is the relation between the hydrogen used and the output of the fuel cell? For instance, I have x amount of hydrogen, at what capacity will the FC work, disregarding the Load? The fuel curve inputs tell you how much fuel the generator consumes to produce electricity. The sample file to which you refer has a fuel curve intercept coefficie

How can i find the rate hydrogen consumption in fuel cell? If you have a particular fuel cell in mind, look at the manufacturer’s specifications for fuel consumption or fuel efficiency data. You can enter those data in HOMER’s fuel curve calculator window. If you have no access to such data, you might want to experiment with different values

I am running some calculations, and I have the attached some genset information I found on Perkins. This information leads me to believe the slope on the fuel curve should be zero? Having said that I had information from Kohler which resulted in a similar curve to what you have in Homer. Did you have any other information on how that curve was calc

Is there a way to model generator availability other than the forced on, forced off, optimized mechanism? HOMER assumes that the generator is available at all times except when it is scheduled off in the generator scheduling tab. You can force the generator off for specific hours for weekends and weekday for each month.

Not having the ability to set the start and stop states of charge for generators independently of the battery minimum SoC. Reason is to enable a battery system to coast through the night if a quiet perod is required (no generator run) without the system shutting down. You mentioned that in some cases the generator cannot run overnight so the sy

I have been attempting to use HOMER and I could not find the way I could input generator efficiency data nor is there a built-in data base of generators to choose from as is the case with wind turbines for example. However, the sample files have examples of microturbines and fuel cells with efficiencies that differ from the default one. In HOM

When a generator is off, it’s off. It won’t cost a cent and it won’t consume any fuel, regardless of the fuel curve. When a generator is on, HOMER will calculate its fuel consumption from the fuel curve. If a generator is actually idling and generating zero kW, then its fuel consumption will be equal to the no-load fuel consumption. That would

I find it difficult to get the generator fuel curves correct and have to fudge to get the right consumption figures You mentioned that you have had trouble with the generator fuel curve, so I wanted to let you know that the new version of HOMER has a "fuel curve calculator" window that helps you calculate the fuel curve slope and intercept inpu

HOMER will always load one generator fully (the generator with the lowest marginal cost) before increasing the load on any other generator, yet real systems often share loads equally between generators. The reason why we have not made load sharing an option is because this has only a small impact on economics, and it doesn't usually affect the resu

Is there a tool for preventing the generator from running too often? You can use the minimum load ratio to avoid running the generator at too low of a load. It's not good to run diesel generators, for example, below some about 25% (or maybe 50% depending on the model) of their fullyrated capacity, or else condensation can occur in the exhaust

What does the O&M cost/hr consist of? Is it fuel cost/hr only or do we also add the regular maintenance cost/hr and top o/haul cost/hr to get the vale to insert in the generator input? Don't include the fuel cost in the O&M cost. You enter the fuel price separately, and HOMER tracks fuel usage and reports annual fuel cost. Include ev

I am trying to setup a generator spec file; the details I have is that: Fuel consumption 2,4 L/Hr / Fuel price 3,6 Rand / O&M cost 0,5 (Rand/kWh) / Rated Capacity 8 (kVA) / (plus some other details that I can see where to put). How would I "translate" the above info so it matches the various HOMER input fields (eg. capacity in KW/hr)? Let'

Actually I am working on a wind/diesel project and I have rebuilt the system with the HOMER simulation tool. The actual simulation step time is 10 minute. The number of the diesel starts seems to be too high but unfortunately I have no data of the number of starts in the real system. The number of starts is getting less in the case of a simulat

Product: HOMER Pro 3.11.5 There are many different approaches to sizing a genset. Autosize Genset: The autosize genset uses the method described in it’s description: “This generator automatically sizes itself to meet the load. The capacity of the generator will be the smallest that will produce no capacity shortage in all sensitivity cases an

A PV fuel-saver system is a hybrid system that consists of solar PV and diesel generator. As the name suggests, this hybrid system is intended to reduce the diesel generator’s fuel consumption. The output from PV serves the load whenever available thus curtailing the use of diesel generators. To build a PV fuel-saver system in HOMER Pro, you will

Is there a way to simulate adding H2 (generated by an electrolyzer) to a natural gas powered generator? HOMER does not have the capability to model a generator co-fired with electrolyzed hydrogen. I can think of a couple of short-term workarounds that you could use if you are willing to do a bit of post-processing of the results. If the ratio

Is it possible to include as an input in the optimization an increasing diesel prices? HOMER assumes all prices, including the fuel price, inflate at the same rate throughout the project lifetime. It's not possible to enter a separate fuel price escalation rate. You can do a sensitivity analysis on the price of fuel, but that's not quite the

A single 910 kW generator is big enough to meet the entire load. When I force HOMER to use an 1820 kW generator with 30% minimum load ratio and a 425 kW generator, during low load periods, HOMER runs the 425 kW generator, but otherwise runs the big one at low load. Modeling the system with two 910 generators and one 425 generator results in only on

How much of an approximation is assuming a linear fuel curve? For typical constant-speed internal combustion generators or microturbines, it's a very good assumption. For fuel cells or variable-speed diesels, it's not quite as good, but still acceptable in most circumstances. In almost every situation, the uncertainty in key input values (loa

I am a little perplexed at HOMER’s output calculation of the “Marginal generation cost” under the tab “generator 1” in the simulation results. I would assume that marginal generation cost would be the $/kWh not including capital costs (i.e. just fuel at the diesel’s average efficiency and O&M). However, the number that HOMER always displays her

Is there a minimum run time for diesel in HOMER? and is it possible to specify it? No, but if the system contains a battery and use are using the cycle charging strategy, you can effectively set a minimum run time by applying a setpoint state of charge. That way, once the generator starts to charge the battery bank it must keep running until t

Can you replace the diesel engine as generator by an engine of the type DUAL-FUEL? HOMER can model a generator that burns a mixture of diesel fuel and biogas. Is that what you had in mind? To use that feature, check the checkbox labeled ‘Cofire with biogas’ on the Fuel tab of the Generator Inputs window.

How can insert fuel cells, for example, PEM, to cover the electrical needs (an electrical load)? A fuel cell is a type of generator, so you use the generator module to model a fuel cell in HOMER. Please refer to the FAQ page of the HOMER website for more information. If the system will electrolyze excess electricity to make hydrogen that the

Why are you giving an option of hydrogen load instead of a hydrogen fuel cell? HOMER models hydrogen fuel cells. The hydrogen load is entirely different from a fuel cell. Use a hydrogen load only if you want to simulate a system that produces hydrogen for some external use. To simulate a system that electrolyzes excess electricity to produce

Can you please tell me how I can connect hydrogen tank with diesel generator? To model a generator that consumes hydrogen from the hydrogen tank, go to the Fuel tab of the Generator Inputs window and select "Stored Hydrogen" from the Fuel drop-down box. HOMER can't model a generator that consumes both diesel and hydrogen.

HOMER can model variable-speed generators. The principal feature of a variable-speed generator that distinguishes it from a fixed-speed generator is its fuel consumption curve. On the Fuel tab of the Generator Inputs window, you enter the generator’s fuel curve, which specifies its fuel consumption versus its power output. HOMER assumes that fue

Is the thermal load capturing excess heat from the generators? Excess heat from a generator serves the thermal load if you specify a non-zero heat recovery ratio on the Fuel tab of the Generator Inputs window. The Help system contains more information on that parameter – you can find it if you look up ‘heat recovery ratio’ in the index. The s

HOMER can model CHP systems. If you set the generator heat recovery ratio to a non-zero value, waste heat from the generator will serve the thermal load. For more information, look up ‘CHP systems’ in the index of the Help system.

Can I model a cogeneration unit to supply the electricity and heat demand simultaneously with HOMER? Yes, you can model cogeneration with HOMER. To model heat recovery from a generator, set the "heat recovery ratio" to something greater than zero. That input is on the Fuel tab of the Generator Inputs window. You can also use excess electrici

I was looking for mention of industrial gas turbines in the HOMER information sections. Is HOMER appropriate for this equipment, or only smaller devices? HOMER can certainly model industrial gas turbines, compare their economics to other alternatives, and help determine optimal sizing. But it might not model them to the degree of detail that y

How is the recovered heat percentage calculated without an outlet temperature of microturbines flue gas? HOMER models heat recovery from generators in a very simple way. It assumes that the generator converts all the fuel energy into electricity and heat, and it asks you to enter the portion of that heat that can be recovered to serve the ther

Is it possible to model the use of an ORC unit using waste heat from a diesel generator(s)? Another way to model an ORC system would be to simply add its electric output to the output of the diesel generator it is connected to so that its fuel curve relates the fuel input to the combined output of the diesel with its ORC unit.

I am trying to make it work as a standard diesel unit. To show the benefit of the whpp I increased the efficiencies of all the diesels by 10% from changes in the slope and fuel intercept. I am worried this might not be accurate because of how HOMER is programmed to run the diesel optimally. The fuel curve slope and intercept refer only to the

It is certainly possible to model a thermoelectric generator in HOMER, and it should be fairly straighforward. The fact that the TE generator is either on or off has two effects. First, you want to set the minimum load ratio to 100%. Second, the fuel curve doesn't need to be accurate except at the rated output. So I would set the intercept coef

You mentioned you would like to model thermophotovoltaic generators but cannot with HOMER. In fact, HOMER is capable of modeling a TPV generator that burns fuel. If the TPV generator operates off waste heat from some industrial process, it might be difficult to model it in HOMER. But if the generator consumes fuel to produce electricity, it is j

Part of the system I am modelling uses micro-CHP. I have looked at the cogeneration sample given within the programme, but am unsure about the inputs for the microturbine 'Fuel' section. I am using natural gas, and have a maximum consumption rate of 2.7m3/hr, when the burner output of 6.5kW is generating 1kW of electricity. Is the 'size' of the tur

I am trying to determine the optimum size for an additional diesel generator. I have aggregated the hydros, and entered 2 of the existing generators as GEN1 & GEN2. The question I have is with the proposed GEN3. I have entered the "sizes to consider" and the "fuel consumption data for GEN3 but I am unsure how HOMER distinguishes fuel consumptio

When trying to creat a new fuel for a gernerator my 'new button' is disabled and I don't know why. Do you know how to enable this button? HOMER disables the fuel button only if the current fuel is "Stored hydrogen"or "Biogas". Choose any other fuel and you will be able to click New.

Can I change the value of the O & M cost for certain components? If you are looking at a file where someone entered $500/yr for the O&M cost of a component, and you think $600/yr is a better number, and you are asking me if it's okay to change it, yes it's okay to change it. You should enter whatever numbers you think are most realisti

How does HOMER treat the propane fuel usage ratings? HOMER doesn't contain any hard-wired assumptions about propane or any other fuel. When you choose "Propane" from the list of fuels, you are choosing the properties of the fuel including the density. The "Propane" in the default library of fuels has a density of 510 kg/m^3 which corresponds

In my HOMER simulation, three diesel generators run sometimes even if the load is smaller than two diesel generators. My system has three 150 kW generators, 120 kW PV, 100 kW wind, 500 kWh of batteries, and load between 80 and 310 kW. If the operating reserve is 10% (the default), and the load is 290 kW, the total available capacity must be 319 kW

I am trying to run a simulation whereby two generators of equal size are intended to share the load (during peak times). The issue is that when the results are captured, only Genset B or 2 operates to meet the load. Can you please provide some insight in how I can resolve this? HOMER will make a decision based on lowest cost. Typically there's

It is possible to specify the generator fuel curve with a quadratic function to provide a better fit to real data. We haven't included the option in the regular generator menu to keep things simple for the majority of users. To access the nonlinear fuel curve option: 1) Go to the library view, and open the generator list in the left sidebar. 2) Sel

I would like to model the battery capacity of an energy system such that the battery kicks in when the solar resource is down so that the diesel generator does not go ‘on’ and ‘off’ for short periods of time. Is there any way to make sure that I don’t have instances of the diesel generator on for less 10 minutes (for example). Yes. First of

Concerning the help-example for Fuel curve intercept coefficient. Does the example have any relevance? From a technical data sheet provided by a fuel cell manufacturer, the hydrogen consumption for a 1 kW FC is approx. 900 liters per hour at rated output. The FC in the help-example consumes some 6.5 liters per hour at 20 kW rated output! What are

HOMER doesn't have a checkbox to disallow wind-only operation, but if you set the operating reserve as a percent of wind power to 100%, you get the same effect. Say you do that and you also set the operating reserve as a function of hourly load to 30%. Then in some hour if the load is 50 kW and the turbines are producing 80 kW, the required opera