Is LNG a Better Alternative to Diesel for Generators?

[Home Improvement]

Hi all,

This is related to this thread https://www.physicsforums.com/threads/solar-batteries.928495/
I just heard that in 2 - 3 years, the LNG mains will be installed in my area.
I need some help to gather info on modern LNG generator performance (the latest models, just in case the older models still have poor performance or other complaints compared to diesel generators).
I've heard about complaints regarding LNG generators that they tend to break faster, not as resilient as diesel. also that diesel is more efficient at generating electricity. not sure if this is still the case for modern models.
The price of electricity in my area is 1500 IDR per kWh and the price of LNG is 4820 IDR per m3.
How much electricity (kWh) does modern LNG generate per m3 of LNG?

can anybody share their experience, the good and bad of LNG generator? any recommended brand on LNG? my electricity daily consumption averages 10 - 11 kWh.

thanks

 

[russ_watters]

You mean a gaseous natural gas main, not liquid, right?

You should be able to Google the energy capacity of natural gas and estimate the performance of a generator (probably around 30% efficiency) or better yet Google for candidate generators and see what their spec sheets say.

But as said in another thread, if home generation was cheaper, we wouldn't have a grid.

 

[Home Improvement]

You mean a gaseous natural gas main, not liquid, right?

You should be able to Google the energy capacity of natural gas and estimate the performance of a generator (probably around 30% efficiency) or better yet Google for candidate generators and see what their spec sheets say.

But as said in another thread, if home generation was cheaper, we wouldn't have a grid.

perhaps, the company just said LNG is distributed via the pipes. not sure if it's in liquid or gaseous form, but logically, it should be the latter.
as for data, I prefer real experience from actual usage.
from this
http://www.dieselserviceandsupply.com/Natural_Gas_Fuel_Consumption.aspx
the calculation is pretty much the same between LNG and local grid, which I highly doubt...
who knows, with modern generators, the efficiency has increased or whatever.
I also have the feeling that it would be more expensive compared to the grid, but by how much. if the difference is in single digit percentage, that would make alternative energy more acceptable

 

[Dr.D]

The practice of running diesel engines on natural gas is long established. In the natural gas transport industry (cross country pipelines), most of the compressors that move the gas run on the gas being moved in the pipe. Its clean, easy to use, and the biggest modification to the diesel that is required is the installation of a spark plug.

 

[gleem]

the company just said LNG is distributed via the pipes. not sure if it's in liquid or gaseous form, but logically, it should be the latter.

It is a gas as NG liquefies at -162 deg C. One problem with NG is that you cannot store it. Have you considered propane as a fuel source?

 

[russ_watters]

One problem with NG is that you cannot store it. Have you considered propane as a fuel source?

That isn't much of a problem. The reliability of natural gas distribution is orders of magnitude higher than the electrical grid. So it is often used as a backup without requiring storage.

 

[anorlunda]

from this
http://www.dieselserviceandsupply.com/Natural_Gas_Fuel_Consumption.aspx
the calculation is pretty much the same between LNG and local grid, which I highly doubt...

Based on the numbers in that link, plus the residential price of gas from eia.gov, I calculate that the cost of natural gas generation by that method is about $0.13-$0.24 per kWh. Depending on where you live in the USA, the price of electric power varies between $0.025 to $0.39. So natural gas may or may not be competitive for you.

I remember hearing of the Ballston Spa NY School converting to natural gas electricity generation. They captured some of the waste heat for space heating which changes the economics a lot.

The generator engines appeared to be ordinary auto gasoline engines converted to burn gas. Gasoline engines are much less expensive than diesel engines.

 

[Home Improvement]

Based on the numbers in that link, plus the residential price of gas from eia.gov, I calculate that the cost of natural gas generation by that method is about $0.13-$0.24 per kWh. Depending on where you live in the USA, the price of electric power varies between $0.025 to $0.39. So natural gas may or may not be competitive for you.

I remember hearing of the Ballston Spa NY School converting to natural gas electricity generation. They captured some of the waste heat for space heating which changes the economics a lot.

The generator engines appeared to be ordinary auto gasoline engines converted to burn gas. Gasoline engines are much less expensive than diesel engines.

Hi, I'm not in USA, I'm in Jakarta (capital city of Indonesia, the country next door to Singapore in case you haven't heard about my country), and in my area, the price of electricity from local grid is 1500 IDR per kWh, while the LNG price is 4084 IDR per m3. Also, I forgot to mention that my house's max wattage is 2200W.

 

[Tom.G]

According to Google, IDR 1500 equates to USD $0.111. or 13500 IDR per USD.

 

[Home Improvement]

According to Google, IDR 1500 equates to USD $0.111. or 13500 IDR per USD.

yes, that's correct

 

[Home Improvement]

I stumbled into this thread
https://www.quora.com/How-many-unit...-generated-from-one-meter-cube-of-natural-gas

Density of natural gas = 0.7-0.9 kg/m3. Let's take it as 0.8kg/m3

Calorific value of natural gas = 43000kJ/kg

Calorific value of 1m3 of natural gas = 0.8*43000 = 34400 kJ

Efficiency of typical gas turbine is between 20%-35%. Let's take it as 30%.

So energy converted to electricity = 34400*0.3= 10320 kJ

1kJ = 0.000278 kWh

So electrical energy produced from 1m3 of natural gas = 10320 * 0.000278 = 2.87 kWh

if what's said in that post is correct that 1 m3 LNG can produce 2.87 kWh, then the price per kWh when using LNG is 1679 IDR, which is only 11% more expensive than local grid (1500 IDR per kWh)...
well, that's a surprise
if...IF...the efficiency of latest gas generator has increased, then it's not impossible for LNG generated electricity to be even cheaper than local grid.
I calculated that with minimum efficiency of the gas generator at 33.7%, LNG generated electricity becomes cheaper than local grid

 

[Tom.G]

if what's said in that post is correct that 1 m3 LNG can produce 2.87 kWh, then the price per kWh when using LNG is 1679 IDR, which is only 11% more expensive than local grid (1500 IDR per kWh)...
well, that's a surprise

Remember to count the cost of the generator, how long it will last, how much you could earn in interest if you banked that cost, and the maintenance costs during its' life (such as oil changes, fan belts, coolant, etc.) If I recall correctly, here in the US the utilities consider a 50 year lifetime normal for their equipment. You can not expect that from any commercial product you can purchase.

Overall, I would not be surprised if the actual costs of a generator would be 150% or more of the utility pricing. If reliability of the grid is a problem, then a generator may well be worth the costs. It all comes down to what your priorities are.

 

[tech99]

I thought we were trying to use renewable energy these days. In the UK we are now seeing house batteries to allow solar power to be used for 24 hours, which are about the size of a fridge.
By the way, if you use house heating and hot water, that can be provided direct from the gas, allowing a smaller generator.

 

[Home Improvement]

I thought we were trying to use renewable energy these days. In the UK we are now seeing house batteries to allow solar power to be used for 24 hours, which are about the size of a fridge.
By the way, if you use house heating and hot water, that can be provided direct from the gas, allowing a smaller generator.

most people, me included, don't really care about whether it's renewable or not. we're only interested if it saves money or not:
1. cost --> right now the M&O (maintenance & operational) cost of using the grid is X, what energy that would cost less than X
2. if energy that satisfies #1 is found, look at the initial investment cost. how many years would it take to break even

as for batteries, are you using a bunch of connected car batteries to store the solar energy? how long before we need to change the battery? how does that affect M&O of your solar system? can you show me the breakdown of costs?
present day generators convert fuel to mechanical energy first before finally converting to electricity. simply put, electricity is like the secondary product of the generator. right now, I'm waiting for themoelectric generator which converts heat directly to electricity, but I think it would be quite a while before it's available for retail.

a bit off topic, going to rant for a bit here, most people here in Asia don't really believe in global warming or climate change issue anymore. when NASA showed that the volume of ice caps actually increased (by 20% if I'm not mistaken) in 2012 (or 2013?), global warming was immediately treated as hoax. and now the same group that perpetuated global warming got exposed, they try to change the "brand" of their product as "climate change", well, we call bullshit on that too. so, most people here in Asia consider cost as primary reason when deciding if they'll switch to solar or not, if at all.

 

[tech99]

as for batteries, are you using a bunch of connected car batteries to store the solar energy? how long before we need to change the battery? how does that affect M&O of your solar system? can you show me the breakdown of costs?
present day generators convert fuel to mechanical energy first before finally converting to electricity. simply put, electricity is like the secondary product of the generator. right now, I'm waiting for themoelectric generator which converts heat directly to electricity, but I think it would be quite a while before it's available for retail.

The batteries I have seen are Lithium Ion type made by Tesla. They are also being used by solar farms, where they typically occupy the space of a shipping container. I would also mention that offshore wind is now coming in cheaper than nuclear, and areas are becoming interested in becoming energy-independent. With so much renewable energy being pushed back into the grid from distributed solar installations, the grid is becoming the wrong shape and does not have the required intelligence, as it was designed for central generation. There are also changes in demand for electricity, as we no longer watch TV, which produced big peaks during commercial breaks, and we have electric cars to charge up, which could be switched off if a peak in demand occurred.

 

[tech99]

most people, me included, don't really care about whether it's renewable or not. we're only interested if it saves money or not:

Scientific opinion supports climate change with irrefutable evidence. It is uncomfortable, but we must face up to it.

 

[Home Improvement]

The batteries I have seen are Lithium Ion type made by Tesla. They are also being used by solar farms, where they typically occupy the space of a shipping container. I would also mention that offshore wind is now coming in cheaper than nuclear, and areas are becoming interested in becoming energy-independent. With so much renewable energy being pushed back into the grid from distributed solar installations, the grid is becoming the wrong shape and does not have the required intelligence, as it was designed for central generation. There are also changes in demand for electricity, as we no longer watch TV, which produced big peaks during commercial breaks, and we have electric cars to charge up, which could be switched off if a peak in demand occurred.

tesla's powerwall? according to their website, it easily costs USD 5000. any cheaper alternative? USD 5000 just doesn't make sense.
as for wind power, geothermal power, etc, they're only feasible in large scale. so, it will need to wait for some big company with deep pockets to start a power plant and distribute the power to the houses. these energy is not feasible for individuals. I'm ok with any of those alternative energy so long they're cheaper than the more traditionally dam-generated or coal-generated electricity.

Scientific opinion supports climate change with irrefutable evidence. It is uncomfortable, but we must face up to it.

it was just a rant, not trying to start an argument on global warming or it's continued "hoax" climate change. for now, I don't see any compelling evidence presented by the climate change advocates other than the infamous "98% (or whatever the number is now) of scientists" argument. plus, the increase of volume of ice caps in 2013 dealt the finishing blow to this hoax, resulting in those snake oil salesmen of global warming needing to change their product brand to "climate change". I'm keeping an open mind, if anybody has evidence, not just correlations that are made up as false causations, then I'll be willing to believe. otherwise, it's just propaganda. because as I understand, in the west, climate change is not a scientific debate anymore, it's become so politicized that if you don't believe in it, the otherside will call you names. yeah, here in asia, that will never happen, nobody cares if you believe in climate change or not, hell, some doesn't even know about this.

 

[gleem]

it easily costs USD 5000. any cheaper alternative? USD 5000 just doesn't make sense.

The PowerWall could be the best electrical storage systems available today. and probably will get significantly better. Currently the initial cost per kwhr stored in about 400 $US compared to the cheapest lead acid batteries whose cost is about 100 $US. Tesla is currently producing batteries with a cost of about 270 $US per kwhr. So prices are coming down. Here is a website that compares LI-ion and lead acid batteries for solar.

https://medium.com/solar-microgrid/battery-showdown-lead-acid-vs-lithium-ion-1d37a1998287.

If you compensate for service life, availability of stored energy, cost of maintenance and operation you find the discrepancy between the initial costs of Li -ion and lead acid batteries becomes much less significant.

 

[tech99]

The Wiki article on scientific opinion on climate change seems to provide ample evidence.
https://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change

 

[Home Improvement]

The PowerWall could be the best electrical storage systems available today. and probably will get significantly better. Currently the initial cost per kwhr stored in about 400 $US compared to the cheapest lead acid batteries whose cost is about 100 $US. Tesla is currently producing batteries with a cost of about 270 $US per kwhr. So prices are coming down. Here is a website that compares LI-ion and lead acid batteries for solar.

https://medium.com/solar-microgrid/battery-showdown-lead-acid-vs-lithium-ion-1d37a1998287.

If you compensate for service life, availability of stored energy, cost of maintenance and operation you find the discrepancy between the initial costs of Li -ion and lead acid batteries becomes much less significant.

I see. if the battery cost can go down to 270/kWh, then perhaps my dream solar system can be revived. currently it's dead because of the battery initial and M&O cost problem. maybe I'll wait for another 7 - 10 years before actually moving to solar panel, or perhaps, I can even go off grid completely. hopefully that giga factory of Tesla's can really drive the battery price down.

 

[Home Improvement]

The Wiki article on scientific opinion on climate change seems to provide ample evidence.
https://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change

notice how even wikipedia's article is titled Scientific opinion on climate change, they're careful not using the word evidence, because they're still not sure. there's still no compelling evidence at this time, so, it's still an open question. nothing's decided yet.
these are just a bunch of opinions, not evidence. correlation without causation.

 

[anorlunda]

hopefully that giga factory of Tesla's can really drive the battery price down.

I wish you well on your dream. But you should be aware that better battery technology is likely to come first to power company grid scale devices, and to micro grid installations capable of supplying a neighborhood at a time, and to electric vehicles. Individual size residential batteries might be developed last.

So, if you are willing to bend your dreams to fit technology rather than waiting for technology that fits you, you might find fulfillment more quickly.

 

[Home Improvement]

I wish you well on your dream. But you should be aware that better battery technology is likely to come first to power company grid scale devices, and to micro grid installations capable of supplying a neighborhood at a time, and to electric vehicles. Individual size residential batteries might be developed last.

So, if you are willing to bend your dreams to fit technology rather than waiting for technology that fits you, you might find fulfillment more quickly.

so long the economy calculation checks out, I'm okay with anything. I'm also waiting for EVs to become more affordable, so when I move to solar, I get both house and car power supply in one go.
but yeah, if the new technology is adopted by govt like in your scenario, which I assume would reduce the price of electricity from local grid, then most likely I'd stick with local grid and perhaps use the then affordable tesla's powerwall as backup.

 

[mfb]

notice how even wikipedia's article is titled Scientific opinion on climate change, they're careful not using the word evidence, because they're still not sure. there's still no compelling evidence at this time, so, it's still an open question. nothing's decided yet.
these are just a bunch of opinions, not evidence. correlation without causation.

You are misinterpreting how the title was chosen.
The scientific opinion is that there is overwhelming evidence for a man-made contribution to climate change. That's what the article text says, and therefore the article has "opinion" in its title.

hopefully that giga factory of Tesla's can really drive the battery price down.

With the demand they have, I wouldn't expect that. In addition, their focus is on car-suitable batteries with a high energy density and reasonable power density. A grid storage would pay more attention to cost/kWh.

 

[anorlunda]

A grid storage would pay more attention to cost/kWh.

Both cost/kWh and cost/kW. For example, if you have storage that can store a day's energy in only one hour of charging, that has value. The higher the kW rating, the more operational flexibility.

Even for home solar use, it is vital that the rate of charge fit with the 5 hour window of full solar power and that the rate of discharge allows peaks like 1 minute on the microwave oven, or an on/off cycling water heater. The peak kW capacity needs to be 10 to 20 times average capacity.

 

[Evanish]

Both cost/kWh and cost/kW. For example, if you have storage that can store a day's energy in only one hour of charging, that has value. The higher the kW rating, the more operational flexibility.

Even for home solar use, it is vital that the rate of charge fit with the 5 hour window of full solar power and that the rate of discharge allows peaks like 1 minute on the microwave oven, or an on/off cycling water heater. The peak kW capacity needs to be 10 to 20 times average capacity.

Many places have large seasonal differences in sunlight, so it seems the length of time a battery can keep it's charge is also relevant.

 

[mfb]

Seasonal battery storage is way too expensive. You need at least hundreds, better thousands of cycles to make the cost/kWh reasonable. That also sets some limits on the typical charging/discharging time.