Crazy ægreen machinesÆ 1

[KENAT]

I thought I’d start a thread for people to suggest some ‘green machines’ following on from my post about exchangeable battery packs for vehicles.

I know not everyone, or even most members believe it’s necessary but lets ignore that temporarily and pretend we all think it’s a good idea to reduce the use of fossil fuels, especially oil.

What cunning machines, techniques, systems, mechanisms etc do you have for saving energy or generating it in ‘cleaner’ ways, and to keep it on topic ones that could be realized (at least in prototype/proof of concept form) in the next 5 years.

Obviously if you think it’s a really good idea you may want to save if for your patent application, since once on this board I suspect anyone could use it although I’m no expert on patents or copyright law etc.

Try to think outside the box a little, ideas that aren’t receiving much if any attention at the moment, perhaps do a quick internet search before you post just to check.

So for starters, wind turbine powered ships. Especially a vertical axis wind turbine powered ship.

The direction of travel would be completely independent of the wind direction, you wouldn’t even need to tack.

If a two blade ‘H’ configuration or egg beater configuration were used then in port auxiliary power could be used to avoid any dangers of collision with the turbine locked for and aft.

Once at sea the turbine could be unleashed.

Classically ‘H’ vertical axis wind turbines have problems with peak power being provided n times a rotation for an n bladed turbine.

This can cause problems with a torque tube as well as being non optimal for driving a generator.

This can be alleviated by ‘twisting’ the blades around the axis but using this would complicated stowing the turbine for and aft as above.

On the ship maybe a ‘power smoother’ could be used. Perhaps a hydraulic pump at the hub connected to a hydraulic motor for the propeller via an accumulator to smooth the rotation.

This is about the only thing I could find which isn’t quite what I’m thinking of.

http://www.memagazine.org/supparch/pejun04/ebursts/ebursts.html

So obvious problems and flaws with the idea.

Or have any of you got your own ideas that you think Engineering might explore in the next 5 years?

 

[dcasto]

The work extracted from the turbine is removed as cooling of the fluid. You can then warm the fluid up by cooling down the process. I reran my scenerio above with some slightly different materials, but here are the results. With 180,000 lbs/hr of Ethane at 1000 psia, letting down to 200 psia, then warmed back up to its original temperature of 70 F, the amount of refrigeration available with just a valve letting the pressure down is 733,000 BTU/hr. If the valve is replaced with a turbine, the turbine will generate 542 HP @ 72% eff and the amount of refriberation is 25,500,000 BTU/hr.

 

[epoisses]

The idea of living in an underground house, with a shower that drips but doesn't spray because of the freaking turbine to save 0.3 Watt... to go outside only with the idea to drive around in a Yaris... now that is pretty depressing!! :-D

I wonder how my family and I fit in this picture. Because of the soaring electricity prices in France (yes, no gas no fuel, our heaters run on nuclear electricity), we went back to the stone age and are now heating the house using only the chimney (and a bit of electricity in the bedrooms of the girls). The price of the wood is roughly half the price of the electricity calculated per winter day.

Our great-grandparents did it and it did not cause global warming at the time... moreover we now live in a relatively well-insulated house so should need less wood than they did...
only it's MUCH more air-polluting than the Watts from the nuclear plant down the road.

 

[epoisses]

(just for clarity, most French have gas for heating, it is just that we live in the middle of nowhere)

 

[KENAT]

Burning wood from a sustainable source doesn't have a net CO2 contribution. Good for you.

We used to burn wood at my last place in the UK. Again in the middle of no where and although we had central heating from bottled propane that got expensive so except for really cold days or to take the chill off in the morning we use the fire. Only thing was we'd often put a little coal in the bottom to improve things which obviously isn't so 'green'.

 

[hammerforge]

On the other hand...disposing of wood ash contains considerably less issues than disposing of nuclear wastes. And certainly modern woodstove inserts with reburners are less poluting than the old style ones.

 

[0707]

I have a small field house where I go some times for weekends. The house has an old style fireplace. In the cold nights of winter I like to be at the fireplace seeing the fire and setting fire live coals. The fireplace will not be a crazy green machine but it pleases me and I forgive myself for co2 emissions.

luis

 

[SomptingGuy]

Some people might think of "wood ash" as fertiliser.

 

[0707]

In my infancy, when my parents were farmers, they used to put wood ash in the borecoles, for a good and healthy growth.

luis

 

[KENAT]

So not a crazy machine as such but…

With current technology Hybrids are more expensive to purchase than conventionally powered automobiles. From some figures I’ve seen then even with some of the tax breaks available (at least in the US), with anticipated fuel prices, an average user will most likely only just break even over the life of the vehicle. As well as the financial cost there have been questions over whether any extra energy required to make the hybrid compared to the conventional equivalent is recouped, and hence just how ‘green’ they are.

To counteract this it would make sense for hybrids to initially be used in situations where they can get most effect from their regenerative breaking, which is where most of the efficiency improvements are generated. Effectively this means in situations with frequent decelerations, some kind of “stop – go” driving.

Obvious examples of this would be vehicles that spend a lot of time in city, or even highway, congestion and vehicles that due to the nature of the task they are used for make frequent stops, e.g. urban delivery vehicles.

Furthermore if any of these vehicles form parts of fleets that stand idle for several hours a day, especially over night, this would support the possibility of being plug in hybrids – with further decreases in emissions from the vehicle itself.

Then if these vehicles form parts of large enough fleets to warrant their own re-fueling facilities this opens up the possibilities of using alternate fuels without directly relying on the existing gas (petrol) station & distribution system. This may allow use of pure, or near pure ethanol (which can cause problems in the current gasoline distributions system), bio-diesel (including perhaps a co-located recycling scheme for cooking oil not just from restaurants but even private citizens), bio-gas, hydrogen or even just natural gas.

I’m thinking the most obvious candidate is the Post Office. In the US at least they have a large fleet of what appear to be more or less custom vehicles. In urban areas they make frequent stops and don’t tend to go that fast or accelerate that hard which would support greater use of the electrical component of the hybrid drive, as well as the fact they probably don’t need great range. They generally sit in the Post Office parking lot overnight, good for plugging in & charging up, and generally operating from centralized location would be amenable to their own refueling facility.

If you want to take it to the real extreme then waste oil/fat collection facilities could perhaps somehow be added to your post box. The Post office employees could then collect the oil at the same time they drop off mail. Can’t see the union liking that though.

Obviously post office isn’t the only candidate. Any kind of urban delivery vehicle, be it UPS/Fed Ex type fleets or even just the delivery vehicles for the various types of store that offer delivery, would be areas of interest. Likewise, Buses, for which there are already hybrid vehicles in the works if not already in large scale production. Taxis are also an option, I’ve read articles of some cities taking steps to encourage this. I could imagine the next version of the ‘London Cab’ being an hybrid (maybe plug in but I know some taxi fleets are operated almost around the clock) and if it was to US vehicle standards I’m sure there’d be a market in New York & LA etc; I’m sure a lot of Americans would get a kick out of riding in a London Cab type vehicle!

Just my thoughts…

 

[KENAT]

Again not a green machine as such but…

I was wondering just the other day why governments don’t push for more efficient light bulbs (or bulb substitutes) for general home use etc. Looks like at least some of them are taking action.

http://www.msnbc.msn.com/id/17364944/

I was thinking along the lines of a tax on regular incandescent light bulbs, or at least those which constitute the main source of energy usage, I’d guess any in the range from 40W to 100W.

Initially the tax could perhaps start out at say the equivalent of around $.5 per bulb and increase in steps maybe every 6 months or a year until the average price on an incandescent bulb was around the same level as for compact fluorescent lamps (CFL) of equivalent brightness.

The money from this tax could be used in a number of ways on related areas, rather than just being poured into the general slush fund.

First, low-income households should probably be given some kind of assistance to deal with the increased up front costs. Maybe a one off payment, or vouchers, of a high enough value to replace the number of bulbs in an average home with CFL. Or if the voucher route is taken perhaps they’d only be able to use the voucher at a store if they present a burnt out incandescent bulb. Whatever best minimizes fraud while keeping admin costs down.

Secondly some of the money could be used for research projects into LED and other more efficient forms of lighting.

Third some of the money could be used to subsidize LED ‘bulbs’. As the income from tax on incandescent bulbs decreases with their reduced usage so would the subsidy on LED bulbs until it ends and any small remaining revenue from tax is used for research.

However, this is more politics than engineering so I should probably stop this nonsense now.

 

[KENAT]

Or how about motion sensors on street and public lighting.

I seem to recall being told that part of the reasoning behind streetlights is that they use some of the excess electricity typically available at night. So it may not make much sense from that point of view. However perhaps with some of the changes in power generation/distribution this isn’t as much of an issue anymore.

Also much street lighting comes from ‘bulbs’ that take a while to ‘warm up’ so it may not be practical from that point of view, especially when it is being used for the benefit of traffic.

Also there may be better ways of reducing the energy used by street lighting, wikipedia lists some.

http://en.wikipedia.org/wiki/Street_light

Any more obvious flaws?

 

[KENAT]

So seeing as I’m on a roll (or am I just talking to myself)

I saw an article a while back on storing energy as compressed air in underground caverns etc.

If I recall correctly the plan was to use any excess electrical energy (typically overnight but maybe as part of smoothing intermittent sources such as wind etc) to drive compressors and put the compressed air into the caverns.

When electrical energy was required the air would be exhausted through turbines to re-generate electricity.

I guess effectively they’d work in a similar way to pump/store HEP systems but using air instead of water.

Now if I remember correctly most compressors, reach a point of diminishing returns at which they just cant pump the air to a higher pressure, at least not with any efficiency.

This limits the pressure to which the stored air could be taken.

However, what if once the air was compressed to the maximum practical value it was then heated. I can imagine either large electrical heating coils or maybe even geothermal or perhaps waste industrial heat being the heat source.

The system could then operate almost as a giant pulse jet!

So what are the obvious flaws?

 

[csd72]

How about a giant electrical generator that is powered by the earths magnetic field.

 

[dcasto]

Underground air storage is peak shaving, you generate power all night and store it up and when demands are highest you release the stored energy. The savings is not effiency, its to keep from building a power plant from coming on for a few hours per day only.

The effiency of a stored air system is as follows. The excess electricity is used to compress air to 1000 or 2000 psi at about 80% efficency, the the air is let down through an expander (turbine) at about 75%, net effiency is 60%, if the electricity came from a 60% effiency power plant, overall effiency is 36%.

No free lunches here.

If you have waste heat to heat the air, why not just add waste heat recovery at the site of the generation and not mess with the storage step.

 

[moltenmetal]

dcasto: no air compressor I've ever seen would be able to make beneficial use of the heat of compression: materials of construction, wear requirements etc. tend to require them to run cool and hence lose a lot of heat. The underground reservoir is also not exactly a place where you can store this air permanently hot (i.e. at its compression discharge temperature). So the compression "efficiency" in terms of energy beneficially stored in the cavern has to be less than the 80% you've stipulated. And unless you have a huge air-to-air exchanger to re-heat the air on expansion, you lose yet more of the stored energy. I can't imagine there'd be much point to using compressed air at these pressures as an energy storage medium due to these factors.

Pumping water doesn't suffer from that particular problem- no heat of compression to worry about. If you happen to have a good sized hydroelectric dam on the grid, you just pump water up gradient to do your peak shaving and use the reservoir as an energy storage. Much more efficient, though limited in locations where you can do it. I'd imagine grid losses would eat up much of the benefit if the source power plant was too far away from the dam.

 

[pipehead]

A reciprocating compressor can approach 80% effiency at small ratios. Then the heat is removed during each stage. As for water pumping, you have not seen the discharge temperature across the pump going up? I started a boiler system once and let the water circulate while I dashed to lunch (no fuel to the boiler just min flow valve working). Came back and the whole systems was 200F.

Some underground storage caverns have temperatures of 150F.

Compressed air storage is proposed for the likes of say Houton, Texas where there is no resivoir 300 feet up a hill to store water.