producing electricity for 1/3 the cost (T&C's apply) - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 06:58:01 am
content: Ok before we start this academic discussion a couple of points: firstly this will only be valid in the winter when you need to heat your house anyhow, secondly it does not consider materials costs.if one was to run a bank of thermo electric generator cells on a radiator connected to the house heating system one would get electricity. Gas costs 1/3 what electricity does and any wasted heat is being used to heat the house anyway - simple ?

author: IanB
author_rank: Super Contributor
timestamp: March 26, 2012, 07:25:45 am
content: Wow, gas really does cost 1/3 of what electricity costs. Forget the thermo electric generator cells (that's a bit impractical), but it certainly seems like it might be economical to install a gas powered generator for your electricity and use the waste heat for hot water and home heating. What an earth is going on with energy prices in England? (I must check what's going on in California after I finish posting this.)

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 26, 2012, 08:34:08 am
content: since we dont have winter... can you provide link/picture to what is "thermo electric generator"?actually my question meant is... for the $1 gas, can you produce $1 electricity during the winter?

author: EEVblog
author_rank: Unknown
timestamp: March 26, 2012, 10:35:41 am
content: Quote from: Mechatrommer on March 26, 2012, 08:34:08 amThat's the baseline question.Using the best gas powered generator available, who much $ of electricity do you get for $1 of gas?Then once you have the baseline, work out if it's feasible from there.Dave.

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 11:33:39 am
content: Quote from: IanB on March 26, 2012, 07:25:45 ampower stations are 30% efficient

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 11:38:31 am
content: I'm not sure how the gas turbines work but assume it means burning the gas, that means getting the waste heat out of the fumes, I guess it could be done by putting the exhaust through a radiator, but that all gets complex.

author: grumpydoc
author_rank: Super Contributor
timestamp: March 26, 2012, 12:14:28 pm
content: QuoteWhich you won't get anywhere near for a small generator.That said energy prices in the UK are high and what with the insane (IMO, of course) approach we're taking at present to generating capacity going to get higher. It will soon be cost effective to install a diesel generator and disconnect from the grid completely.Eg my last bill came to £0.16/kWh, a quick back-of-envelope calculation suggests fuel for a 3kW generator comes to £0.33/kWh - it's mad that these numbers are so close.Edit: Hmmm, re-reading the above I half wonder whether Simon is onto something. Not "thermo electric generator cells" - anything which converts heat to electricity has next to no efficiency at all but a gas turbine connected to a generator might actually be plausible.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 26, 2012, 01:21:52 pm
content: heyI did some experiments , and the result was :using gas to boil aprox 1 liter of water - 482 sec (water - 17C to 100C/ ^T=80.8C)using electricity to boil aprox 1 liter of water- 220 sec ( water - 17C to 100C / ^T= 80.8C)gass give me 708W (the useable power )electricity give me 1620W ( the usable power )1Kwh of electricity= 2.5488Kwh of electricity ( both are rated as for the useable power )the time and the temp . red by the 287 , I run trend and it was quiet linear curvethe efficiency of the gas was 44.45% , and the electricity was 73.633%for 2 month I pay aprox 59$ ( using gas )and for 2 month of electricity use I pay 67.7$ok . 7.8$ difference .... not allotI hope someone gain/ed somethinghappy disscussion !

author: slateraptor
author_rank: Frequent Contributor
timestamp: March 26, 2012, 02:45:03 pm
content: Quote from: Simon on March 26, 2012, 11:33:39 amIsn't the power you consume charged on a PF corrected basis? If so, that would make power station efficiency irrelevant.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 26, 2012, 02:47:18 pm
content: ..of course the artifically high prices of solar feed-in tariffs may provide some interesting opportunities for creative uses for conversion of gas to electricity...

author: IanB
author_rank: Super Contributor
timestamp: March 26, 2012, 03:13:43 pm
content: A 'diesel' generator running on natural gas will not be as efficient as a power station in converting gas to electricity, but most of the inefficiency is due to waste heat lost in cooling the engine and disappearing up the exhaust. If you were going to burn the gas anyway to heat water or to heat your home, then capturing that waste heat from the generator and using it for home heating makes the total system efficiency much closer to 100%. Once you have absorbed the capital cost, it would almost be like getting "free" electricity.

author: westfw
author_rank: Super Contributor
timestamp: March 26, 2012, 03:55:12 pm
content: This is the premise behindhttp://www.bloomenergy.com/, right?If you can conveniently and somewhat efficiently convert natural gas to electricity, you can save money.But only in the somewhat artificial environment where gas is significantly cheaper than electricity. If everyone did it, the price structure would change (sort of like electric cars. If a small percentage of people charge their electric cars during off-peak hours, they get to take advantage of a glitch in demand-based pricing. If everyone were to do it, we'd have rolling blackouts at night as well as during the day.)(There was an interesting study out of Canada that someone posted somewhere, pointing out that incandescent bulbs were actually less carbon-polluting than CFLs, because they ended up heating homes with hydro-electric generated electricity (carbon-free) instead of fossil-derived natural gas. Interesting, in that it points out just how complex the whole energy-usage equations really are...)

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 04:29:33 pm
content: Quote from: IanB on March 26, 2012, 03:13:43 pmmy point exactly

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 04:30:36 pm
content: Quote from: slateraptor on March 26, 2012, 02:45:03 pm1 KW gas into the power station = 0.3KW of electricy out and 70% heat, nothing to do with power factor

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 04:44:18 pm
content: Quote from: westfw on March 26, 2012, 03:55:12 pmMy idea is that you are using the gas to make heat anyway, electricity is more expensive because you need 3+ KW of gas to make 1 Kw of electricity so really when you buy electricity you are actually buying gas at a better rate and paying the for station running / maintenance. It will never be cheaper than gas unless we stop using gas to make it.

author: IanB
author_rank: Super Contributor
timestamp: March 26, 2012, 05:23:24 pm
content: Quote from: westfw on March 26, 2012, 03:55:12 pmThis is not really an artificial environment. Firstly as Simon points out, electricity is three times more expensive than gas per kWh because power stations have a conversion efficiency of about 30%. And that is not counting the infrastructure costs of electricity generation, transmission and distribution.Furthermore, in parts of the world like the UK and California much of the electricity is already generated using natural gas as the fuel. There is a steadily decreasing use of coal in power stations, nuclear is going nowhere fast, and wind power is a gnat's piss in an ocean. When power companies are using the gas to generate electricity anyway there is no distortion of demand if consumers divert some gas to do the same at home.

author: Simon
author_rank: Unknown
timestamp: March 26, 2012, 05:29:39 pm
content: using gas to make electricity is criminal in my opinion, it is so wasteful of a precious resource. But if I need heat anyway....

author: T4P
author_rank: Super Contributor
timestamp: March 26, 2012, 09:49:52 pm
content: Quote from: Simon on March 26, 2012, 05:29:39 pmAnd if they use gas too ... anyway

author: adept
author_rank: Regular Contributor
timestamp: March 26, 2012, 10:17:11 pm
content: Quote from: IanB on March 26, 2012, 07:25:45 amHa ha! California is the most WACKY of all the states in terms of energy! They recently built a 2.2 billion dollar fusion plant... AND IT DOESN'T WORK!! :O (shocker, right?) Anyway, very interesting idea. But why not knock a hole in your wall and use a Peltier device that pumps heat outside and use that flow to make electricity? It would work on the same concept of using your home's waste energy to generate power. Heck, why do people pay hundreds every month to heat their homes and hundreds to keep a REFRIGERATOR inside? eh? Why spend money heating your cooler? And you could make a waterwheel that you put under all your facets to capture the drips and make electricity! Or put piezo's in the tiling to capture your footsteps! Point is Simon, there are a billion different stupid ways that First world country's waste energy. If we collected all of it, we still wouldn't solve the root of all of it: our energy consumption problem.

author: westfw
author_rank: Super Contributor
timestamp: March 27, 2012, 12:02:15 am
content: >> using gas to make electricity is criminal in my opinionAs opposed to

author: Simon
author_rank: Unknown
timestamp: March 27, 2012, 05:53:02 am
content: Quote from: adept on March 26, 2012, 10:17:11 pmQuite, I don't make a habit of wasting power

author: Simon
author_rank: Unknown
timestamp: March 27, 2012, 11:36:00 am
content: Quote from: westfw on March 27, 2012, 12:02:15 amthat should have been using electricity for heating is criminal, although we should also preserve all the gas we can for heating

author: Rufus
author_rank: Super Contributor
timestamp: March 27, 2012, 12:02:41 pm
content: Quote from: Simon on March 27, 2012, 11:36:00 amBeing a relatively clean and portable chemical fuel we should preserve all the gas we can for use in vehicles.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 27, 2012, 12:18:49 pm
content: so... so far with all the "academic discussion", has anyone figured out how much the initial cost is? coz i stumbled upon a thread about free energy from sun (instead of winter), ie $0 bill for the rest of the "lifetime". but when asking about the "baseline question", i humbly left the good thread in peace...https://www.eevblog.com/forum/projects-designs-and-technical-stuff/my-pv-system-at-home-chilean-version/msg66783/#msg66783that will take me 30-50 years to the break even point, i probably be dead by then, and that doesnt account for the running cost and the interest the bank has to charge me.(i'm regaining my budget for neomedium magnets)

author: GrumpyDave
author_rank: Contributor
timestamp: March 27, 2012, 01:43:55 pm
content: I do not know if this is the case with natual gas but I remember having a conversation with an engineer on hydrogen fuel for cars.I asked him why use a fuel cell instead of a combustion engine.His reply was that it is very difficult to burn all the gas and that some of the hydrogen is expelled with the exhaust, where as fuel cells give almost full conversion.Anyone know if this is the case with natural gas? It would lower the efficiency a little more if true..

author: Kevin.D
author_rank: Frequent Contributor
timestamp: March 27, 2012, 01:55:13 pm
content: I have been interested in the progress of CHP boilers (Combined Heat and Power from gas)for a while .There's some interesting stuff (and sneaky politics )going on in the field of microgeneration .I saw an advert by the "calor gas web site " in 2008 about how there's was the first chp boiler and would be available in 2009 ,many other companies jumped on the band wagon too announcing there micro CHP boilers available by "next year",but it never is they just advance the availability date by another year every year you look at there web site.From what I understand Theres basically 2 ways these CHP boilers work one with a fuel cell and the Sterling engine that was developed in New Zealand a few years ago.( I enquired 2 years agoabout the possibility of getting one of these and following web links from a energy company advertising them ended on some Spanish company's web page that was total gibberish ).

author: Kevin.D
author_rank: Frequent Contributor
timestamp: March 27, 2012, 02:16:38 pm
content: Some have asked why the huge discrepancy between cost of electricity and gasper kWh. ? I think it's only going to get wider in the next few years since the electricity companies are being asked(told) to buy much more expensive powerproduced from wind turbines ,nuclear, and solar producers and they have to pass this cost on to customers so the gap between cheap Russian gas and electricity per kWh is going to get even bigger .Now then, you might see that individuals being able to produce there own electricity from cheap gas with one of those CHP boilers is not exactly in line with what various government's may desire in there "energy policy's" .

author: GrumpyDave
author_rank: Contributor
timestamp: March 27, 2012, 02:33:40 pm
content: Baxi have a micro CHP boiler in their latest range and if you live in the UK there is a feed-in tarrif subsidy too (although its 10.5p so is almost the same as you buy it)

author: Lightages
author_rank: Unknown
timestamp: March 27, 2012, 03:07:25 pm
content: Quote from: Mechatrommer on March 27, 2012, 12:18:49 pmThere was no need to leave a thread with questions unanswered. I don't see any question you asked that was not answered.Anyway, there is no such thing as free energy, or even recovering loss energy as heat for free either. Some examples:1. Trying to recover all of the heat from the exhaust of gas burner will cause the burner to not work. The burner depends of proper air flow though the combustion chamber and interfering with that flow and removing the normal convection may cause the burner to not function correctly. So this means that the whole system needs to be redesigned for this requirement, not just an add on can be used. It also means that a power vent must be used and most likely the power required to vent the combustion byproducts will use most of the energy extracted from the waste heat. It all ends up being expensive to implement correctly and almost ineffective.2. I don't have the figures handy but Peltier devices are very inefficient and you would need the whole interior of your house walled with Peltier devices just to extract any power from the hot air and then the house would be cold because the Peltiers would be sucking all of the heat out of the air. Well that last part is an exaggeration as Peltier devices need high differentials in temperature to work so they would basically do nothing.The beginning to the answer to all these alternative energy ideas is to first, USE LESS ENERGY! Once you look at all the energy uses and cut out the things not needed then alternative energy production becomes easy(ier) and the costs for everything go down. Being careful with the use of energy will save much money.So, want free energy? Well it doesn't exist because there is always the capitol cost of the equipment and maintenance. But you can do some things that can make a difference.I won't go further on all the "cheap" ideas to produce energy to offset fuel and electricity consumption from the grid as many of them are mechanical in nature.My end point is that anything you try to do to recover energy using electronic devices from waste heat in home comfort heating or water heating is going to be almost useless and if done incorrectly, it has the potential of changing the combustion process and proper flow through the furnace or heater such that dangerous gases can back up into the house.

author: Rufus
author_rank: Super Contributor
timestamp: March 27, 2012, 03:38:30 pm
content: Quote from: Lightages on March 27, 2012, 03:07:25 pmYes the make do without option is always a popular choice especially with politicians. It means they don't actually have to do anything about their lack of planning, foresight, and investment. They can blame consumers for being wasteful and wanting too much.

author: Simon
author_rank: Unknown
timestamp: March 27, 2012, 04:44:45 pm
content: Quote from: Lightages on March 27, 2012, 03:07:25 pmyou completely missed my point. Firstly I'm not talking about free electricity but at the same cost as the gas. This is the deal, you need to heat you room, so you turn your gas fuelled central heating system on. If you has a "radiator" in the system in the room you want to heat that was covered in peltiers some of the heat would become electricity. Yes peltiers are not efficient but remember you want to heat your room anyway. Yes you don't get free electricity because the heat is converted to electricity so you loose that heat but that heat is not worth x3 as electricity than it does as gas produced heat.Basically you loose nothing.As for recovering the heat from a turbine with a radiator, I don't know of the output pressure of the exaust but charge air coolers / intercoolers used in car turbos have quite a high air flow rate contrary to radiators for fluids

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 27, 2012, 05:04:51 pm
content: Quote from: Lightages on March 27, 2012, 03:07:25 pmyea, my question answered right on the spoti was thinking of asking the next question. but there's no point in doing thatnow this thread, its going to be about the "thermo electric generator". hope politicians and governments dont find it soon enoughor at least the engineers know how to make it more economical, from scrapped metal maybe.@Simon: i do see your point, taking advantage from whats already there (heat differential). what actually meant is, how much cost to setup the generator? peltier device? isnt that as much expensive as solar panel does? and once you setup throughout your wall let say, isnt that going to suck the heat differential making your machine to heat more? (read as more gas usage?) let alone the peltier inefficiency, not to mention the inefficiancy of the device itself acting as "heat containment" wall? i mean the heat from your house will easily go away to the coldness.i'll vote for candles hanged throughtout the ceiling, but not close enough to burnt it, decorate it somesort. light them all up, shut down all the light bulbs, and you saving energy!ps: or double layered clay walls, with lots of air pocket in between.

author: T4P
author_rank: Super Contributor
timestamp: March 27, 2012, 07:41:36 pm
content: Peltiers that can WARM/COOL an entire house down with a big FAN is probably gonna cost alot . alot .

author: Simon
author_rank: Unknown
timestamp: March 27, 2012, 08:51:20 pm
content: @mechatrometer - who ever said anything about walls ? I'm talking about a metal radiator at a certain temperature and the temp difference between that and your room at 16-18C, most cheap peltiers are 67 degrees max so we are looking at around 50C temperature difference

author: Unknown
author_rank: Unknown
timestamp: March 27, 2012, 09:59:25 pm
content: In the UK, or other miserable climates requiring lots of heating, gas fired electricity can be very efficient with waste heat used to heat the building via heat exchange. There are several UK building that have Co-gen plants which produce power at a lower cost than from a grid fired supply.For those of us in more fortunate climates the equation isn't so easy when waste heat has no effective use for heating or cooling over large periods of a calendar year.I've had interest and some involvement in some innovative projects. Evacuated tube solar heat powered absorption chillers, for example. Solar powered air conditioning. And a massiveclub in NSW using gas at a cheaper rate than electricity to power absorption chillers.The caveat being that much of this is based on the wacko derived tariffs for various utilities. Bulk tariffs for gas often have small users subsidising the larger consumers. Electricity tariffs skewed to supplement domestic solar. Efficiency alone is no measure of success, what is cost effective is not necessarily the most energy effluent solution.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 27, 2012, 11:59:13 pm
content: Quote from: Simon on March 27, 2012, 08:51:20 pmso worst then, your heating the peltier, not yourself.

author: GrumpyDave
author_rank: Contributor
timestamp: March 28, 2012, 11:22:45 am
content: Quote from: Simon on March 27, 2012, 08:51:20 pmThe problem of sticking a peltier to a rad is keeping one side of it cool as there will be thermal transfer through the device. You would likely need some form of active cooling (like a h/s & fan) or a passive cooler that radiates heat more efficiently than the rad.

author: ciccio
author_rank: Frequent Contributor
timestamp: March 28, 2012, 01:22:30 pm
content: Many years ago, FIAT in Italy developed the TOTEM (TOtal Energy Module) that was a 0.9 liter car engine (the one that equipped the FIAT 127 small car) powered by natural gas, driving a 15 KW electric generator.The efficiency of the engine was optimized for constant RPM, and it worked: it produced enough electricity for about 15 houses and could heat 2 of them via the engine cooling water.The sold some thousands of them, but decided to not invest any more in these intelligent things, or in any other type of research, following the paved road of all Italian industry: get money from the government..For what I know, Volkswagen and other companies bought the patents, and they are still manufacturing and selling them.This is a link from Wikipedia:http://en.wikipedia.org/wiki/Fiat_totem.There is one still working, after more 20 years, in the thermodynamics lab of a technical high school near me.Best regards

author: tecman
author_rank: Frequent Contributor
timestamp: March 28, 2012, 11:23:40 pm
content: Quote from: Simon on March 26, 2012, 11:33:39 amYour premise is a bit out of date. Conventional steam plants are 30-35% efficient. This limitation is not present in newest NG generating plants that use combined cycle turbines and attain 60+ efficiencies. They utilize a gas turbine that burn NG, and the turbine exhaust is used to generate steam. The steam (typically low pressure) drives a steam turbine on the same shaft. Efficiencies up to 70+% have been demonstrated. Thermo-electric generators have much lower efficiencies.paul