Energy Returned on Energy Invested Thread pt 2 (EROEI) (merg

[yesplease]

To understand why this is a scam you need only to ask yourself why the world's best educated and well-funded farmers did not previously use their own crops for liquid fuel and methane waste for electricity? Why did these guys hand over their hard-earned cash to the oil companies and power generators when they could have saved money and been more competitive then their neighbors?

Because they some combo of
A) Lazy
B) Greedy

There's no reason to go through all the work of growing their own fuel to save money when it will take time away from growing crops that can provide more money than their homegrown fuel will save, provided the price of fuel is low enough. Until recently, it has been to a certain extent.

[yesplease]

dp

[pstarr]

yesplease, you are obviously a socialist.

[yesplease]

pstarr, you are obviously a socialist.

[shortonoil]

All I want to know is; does this plant come with a midget riding around on the shoulders of some big retard - and where are the pigs?

_____________________
We have exceeded the planet's carrying capacity. We have broken the chain.

[pstarr]

All I want to know is; does this plant come with a midget riding around on the shoulders of some big retard - and where are the pigs?

_____________________
We have exceeded the planet's carrying capacity. We have broken the chain.

within the current metaphor you have to ask whether George W Bush is the smart-ass little midget on top or is he the big goofy one down below? I don't think he's either. I think he is the pig shit

[sirrom]

how long does a photovoltaic cell have to be working so that it replaces the energy that was used in the construction,transportation etc of it?

[eric_b]

how long does a photovoltaic cell have to be working so that it replaces the energy that was used in the construction,transportation etc of it?

Most estimates I'm aware of are 2-5 years of daily use. That's for Si PV technology.

[steam_cannon]

Energy Payback from Photovoltaics: Problems in Calculation
Jeff Vail, Theory of Power

Does solar energy-specifically photovoltaic (PV) panels-ever produce as much energy as the energy that was initially invested in their manufacture? Industry, academia, and government all seem to be in agreement that the answer is �yes.� (1)(2)(3) The consensus seems to be that PV produces as much energy as was used in its creation in a time period of 1-5 years, allowing PV to produce between 6 and 30 times more energy over its life than was used in its creation.

http://www.energybulletin.net/22275.html
http://www.jeffvail.net/2006/11/energy- ... taics.html

Dwindling of Rare Metals Imperils Innovation
http://www.informationweek.com/news/sho ... =199703110

Polycrystalline Silicon Shortage Extended: Bad News For Solar Power Pricing For Up To A Decade
http://www.treehugger.com/files/2006/11 ... line_1.php

So besides shortages of refined silicon, there are also problems finding enough rare metals needed for scaling up solar cell production. Solar cell production is heavily dependent on rare metals, enough so that one could even question their sustainability. Recycling these metals out of used solar cells is likely to be a problem, probably about as easy to solve as recycling silver catalyst out of used plastics.

Silver Catalysts
http://www.biophysica.com/silver.htm

Maybe sea floor mining will solve the rare metal shortages? Probably not, but here are some links about these problems.

Treasures from the deep?
http://www.rsc.org/chemistryworld/Issue ... esDeep.asp

Yale Study: Not Enough Metals In Earth To Meet Global Demand
http://tinyurl.com/3czzwr

[WisJim]

More evidence that reducing energy consumption of all types is the real solution.

By the way, our 25 year old PV panels are still working fine, and I expect them to function for decades more. Current PVs seem to be sealed better (between glass and frames, for example) and should last longer yet.

[yesplease]

I've read about a decade, but YMMV. Most people dislike them because they represent a large initial investment and they don't have the means/skill to take the hardware with them if they need/want to move, however they are a lot cheaper over their likely lifetime compared to paying for the same amount of electricity.

[MrMambo]

Hi,

Does anybody know how much "oil" equivalent energy is consumed for each barrel of oil delivered to the market trough ocean transport, and where in the value chain the consumption happens.

Especially I would be interested in figures on theese areas:

1) crude oil extraction
2) crude oil transportation (when on ocean going oil tankers)
3) handling (pumping from land to boat, boat to land)

[yesplease]

For the efficiency of sea going transport, just figure out how much a tanker needs in terms of heavy fuel oil or diesel and compare it to how many barrels it can carry. Extraction and handling are similar IIRC, not too large. I think the biggest energy hit oil takes is when it's refined into different products and ~10%+ energy is lost per barrel.

[MrMambo]

Thanks yesplease!

Do you happen to know anything vaguely about how much heavy fuel a tanker needs on an average trip?

[yesplease]

I found something via G00gl3 that said the Queen Mary moved 15ft on one gallon of bunker fuel, so maybe a tanker gets ~.002mpg? The thing is, a significant portion of bunker fuel is composed of used motor oil or other "waste" products, so the use of refined fuel oil fuel is likely smaller. If you do your own oil changes, you may know that parts stores will collect used oil for free, since they can sell it as bunker fuel. In inland areas I believe they use it for different things, like off-site power generation.

[Concerned]

1 btu = 1 055.05585 joules

About 735 joules of energy is required to lift 15 kg of oil 5 meters

1 barrel of oil has 5,800,000 BTU's Or
5.8mil * 1055.05585 Joules = 6,119,323,930 Joules

A gallon of Crude Oil is equivalent to 3.785 liters, so we have between 3.104 and 3.236 kg per gallon of light sweet crude. Take upper to account for declining light sweet crude.



1 Barrel 3.236kg
Energy 6,119,323,930 Joules
To lift 5 meters 158.564 Joules (Pure oil no water cut. To account for water cut find equivalent lift of water and add to the figure)

For lifting pure oil, no water cut no other transport. Meters and Joules
To lift 1000 meters 31,712.28
2000 meters 63,425.6
4000 meters 126,851.2
8000 meters 253,702.4

We can lift oil for 19,297 kilometers before the energy becomes a sink. Not factoring water cut, transport, refining, infrastructure etc...

[nocar]

I am not an expert on this, but when was involved in a project on 'future transport', the estamation was that for every liter of gasoline used by a car, 1.1 liter had to be taken out from the earth. The 0.1 liter was for extraction, refinery, transport. However, I do not think this issue really was looked into in detail.

nocar

[Ferretlover]

It's been fairly well documented that the EROEI of oil and other non-renewable resources are dropping, due to the increasing difficulty in recovering them. It's also quite clear that increased research and development of solar technology - renewable resources - will be necessary in the future to make up the difference.

My understanding is that the EROEI of oil will continue to fall, but my question is: how much can technology increase the EROEI of solar? Is there some physical limit inherent in capturing light waves and converting it into a usable energy source? This question, unfortunately appears to be purely theoretical in nature, because I am having a hard time locating reliable current EROEI information for solar... I've seen everything from 0.4 all the way up to 30, or even 50!

[EnergyUnlimited]

In general EROEI of solar will depend of location of your installation.
In favorable locations (say California) EROEI of solar is easily high enough to warrant investment.
See below for some data on EROEI (including solar):
http://www.eroei.com/eroei/evaluations/net_energy_list/
Main problem with solar is not low EROEI in general, but intermittency of power supply, lack of applicability at high latitudes and necessity of large and vigorous high tech sector capable to deliver solar devices (that apply to PV in particular).
You will probably need FF or nuclear or other reliable power source to maintain working PV infrastructure.
It would be hopelessly impractical to run it on solar power alone.

[bonjaski]

i think its irrelevant if the EROEI is 5,10 or 20 or 30.

More important is, whats the impact to nature and how many humans you need;
and thats not covered by EROEI.

In the case of photovoltaics, with a highly automated production of silicium and moduls, even with a EROEI around 15, the cost will come down by time ;

also the impact of PV Production to nature is very very low;

on long term PV is the winner (even with low EROEI),
combined with biogas, wind we can then replace a lot of fossil fuels easily;
http://www.heise.de/tr/artikel/97213