Political Crossfire Forums

[MplsBison]

perdidochas wrote:

Other way around. 1kg of H2 has the same energy content as 2.8 Kg of gasoline. That means that you can replace 2.8kg of gas with 1kg of H2. However, most of that difference is meaningless, since H2 requires a pressurized tank.

My bad.

Yes, what would it take to store even 10 kg of Hydrogen in a reasonably sized tank?

[GTTofAK]

I love how idea, put forward by morons and geniuses alike, that relesing masive amounts of one of the most destructive forces in the Universe into the atmosphere is somehow a good thing.

When all the major cities are overcast 24/7, when there is massive flooding and erosion, when there is a food shortage because all the crops have washed away, when the heat is as stifling as the rain-forest, maybe then we will learn that environmentalism is religion and not science.

[perdidochas]

tman_ndsu08 wrote: perdidochas wrote:

Other way around. 1kg of H2 has the same energy content as 2.8 Kg of gasoline. That means that you can replace 2.8kg of gas with 1kg of H2. However, most of that difference is meaningless, since H2 requires a pressurized tank.

My bad.

Yes, what would it take to store even 10 kg of Hydrogen in a reasonably sized tank?

I have no idea. However, think in terms of other gases. A 20 lb (9kg) tank of propane isn't that big--it's roughly the same size as a 5 gallon tank of gas. That would probaly hold maybe 5 kg of hydrogen (Hydrogen is less dense than propane). That means that roughly speaking, hydrogen would take up about the same amount of space as gas. I was more skeptical of hydrogen before these calculations. If we had a good energy source to make hydrogen like a fusion reactor, or we could bioproduce hydrogen, it might be fairly practical.

[ubikk]

Quicksurf wrote:

This again proves that the free market is the best place for scientific advancement. Where there is a will, there is a way.

Anyway, is this cool or what?
:tu:

Will the free market ensure that someone builds enough refuling stations for these cars?

[perdidochas]

ubikk wrote: Quicksurf wrote:

This again proves that the free market is the best place for scientific advancement. Where there is a will, there is a way.

Anyway, is this cool or what?
:tu:

Will the free market ensure that someone builds enough refuling stations for these cars?

Eventually. That is why the BMW version was flexible, and could use gas in places where H2 isn't available.

[ubikk]

GTTofAK wrote: I love how idea, put forward by morons and geniuses alike, that relesing masive amounts of one of the most destructive forces in the Universe into the atmosphere is somehow a good thing.

When all the major cities are overcast 24/7, when there is massive flooding and erosion, when there is a food shortage because all the crops have washed away, when the heat is as stifling as the rain-forest, maybe then we will learn that environmentalism is religion and not science.

Can you explain that more thoroughly? Hydrogen is made from water. So, when you burn it, you're just releasing water that you just took out of the biosphere.

On the otherhand, when you burn hydrocarbons like gasloline or natural gas, you're adding new water to the biosphere by burning all the hydrogen that was previosly attached to oil molecules underground in the lithosphere. Natural gas is 4 parts hydrogen to 1 part carbon. Hydrocarbons like gasoline are 2-3 parts hydrogen for 1 part carbon.

[ubikk]

perdidochas wrote: ubikk wrote: Quicksurf wrote:

This again proves that the free market is the best place for scientific advancement. Where there is a will, there is a way.

Anyway, is this cool or what?
:tu:

Will the free market ensure that someone builds enough refuling stations for these cars?

Eventually. That is why the BMW version was flexible, and could use gas in places where H2 isn't available.

Ideally, people should be able have recharging stations in their homes that use the extra electricity overnight to crack water and fuel their cars. That would be enough for most people's commutes, I bet, and cheaper than gas.

You could even use solar panels to make hydrogen during the day while you're at work.

[perdidochas]

ubikk wrote: perdidochas wrote: ubikk wrote: Quicksurf wrote:

This again proves that the free market is the best place for scientific advancement. Where there is a will, there is a way.

Anyway, is this cool or what?
:tu:

Will the free market ensure that someone builds enough refuling stations for these cars?

Eventually. That is why the BMW version was flexible, and could use gas in places where H2 isn't available.

Ideally, people should be able have recharging stations in their homes that use the extra electricity overnight to crack water and fuel their cars. That would be enough for most people's commutes, I bet, and cheaper than gas.

Nope. It's not.

The efficiency of electrolysis is about 50-70%.www.hyweb.de/Knowledge/w-i-energiew-eng3.html

For compromise, let's assume 60% as the mid-range values. This means that if you use 100 KW-hr of energy to produce hydrogen you get 60 KW-hr (potential) from that hydrogen. The average cost of electricity is about 10cents per kW-h. Hydrogen contains about 34 kW-h/kg. A kg has the energy content of a gallon of gas. To get the same energy as a gallon of gas, it would take about $3.40 in electricity at 100% efficiency. At 60% it would take $6. Let's change that to the overnight prices that some companies charge. Gulfsouth (my local power company) has a special low hour rate of 5.9 cents per kwhr. At that price, the hydrogen would cost only $3.60 per gallon. That's not taking into account that hydrogen needs to be pressurized. At atmospheric pressure, 1 kg of hydrogen takes up 22, 400 liters of space (vs. the 3.8 liters of space a gallon of gas takes up). We have to pressurize it to use it. Let's just pressurize it so that it takes up the same volume as a gallon of gas. that would require it to be pressurized to 93000 PSI. Not something that we can achieve in a garage. 5000 PSI is hard to achieve with a compressor. Hydrogen technology is not for the garage.



A lead-acid battery has an efficiency rate in the 75-85% range, and can safely be done in the garage.


ubikk wrote:

You could even use solar panels to make hydrogen during the day while you're at work.

The problem is pressurization.

[ubikk]

tman_ndsu08 wrote: perdidochas wrote:

Hydrogen cars can be powered in two different ways: 1) Fuel cells; 2) internal combusion. This case is an example of the second.

But how many BTUs is a kg of Hydrogen vs. a kg of 87 octane gasoline?

1 Kg hydrogen = 134,000 BTU's

1 Kg gasoline = 39,000 BTU's

http://bioenergy.ornl.gov/papers/misc/energy_conv.html

You also have to figure that the efficiency of conversion to energy is probably going to be higher with hydrogen. When you burn gasoline for transportation a lot of the energy is lost as heat and thru incomplete combustion.

[MplsBison]

Right.

That all sounds good to me.


But where do we get the hydrogen in masse?


My first guess is electrolosis.


But then where is the electricity coming from?

So assuming we have electricity sources that efficient, why not just use Li batteries to power an electric motor? That's more efficient than hydrogen combustion with zero pollution (carbon or water, if you consider that pollution).

[ubikk]

perdidochas wrote:

The problem is pressurization.

They're trying to get around that by using adsorption and solid state storage technology.

[ubikk]

[quote="tman_ndsu08"]
So assuming we have electricity sources that efficient, why not just use Li batteries to power an electric motor? That's more efficient than hydrogen combustion with zero pollution (carbon or water, if you consider that pollution).[/quote]

At least one company is doing that:

http://www.teslamotors.com

The problem is that a Lithium battery large enough to power a car currently costs more than $40,000. They also have a habit running hot after a few dozen charge cycles which wastes lots of the stored energy, and some even catching fire.

[perdidochas]

ubikk wrote: tman_ndsu08 wrote: perdidochas wrote:

Hydrogen cars can be powered in two different ways: 1) Fuel cells; 2) internal combusion. This case is an example of the second.

But how many BTUs is a kg of Hydrogen vs. a kg of 87 octane gasoline?

1 Kg hydrogen = 134,000 BTU's

1 Kg gasoline = 39,000 BTU's

http://bioenergy.ornl.gov/papers/misc/energy_conv.html
I was equating the kg of hydrogen to it's energy equivalent of 2.8 kg of gas, or 1 gallon of gas. Gallon of gasoline (using the conversion of 2.8 kg/gallon) is about 115,000 BTUS.


ubikk wrote: You also have to figure that the efficiency of conversion to energy is probably going to be higher with hydrogen. When you burn gasoline for transportation a lot of the energy is lost as heat and thru incomplete combustion.


Evidence for these contentions?

Also, how do you account for pressurization? Or in other words, it is almost impossible to carry enough H2 in a car to run, unless you do something to it, like pressurization and liquefaction (which involves keeping it cold).

[perdidochas]

ubikk wrote: perdidochas wrote:

The problem is pressurization.

They're trying to get around that by using adsorption and solid state storage technology.

But they are far from it. With off the shelf technology, the best I've read about has been a tank of hydrogen at 600 bar (600 atmospheres or almost 9000 PSI) that took up 70 liters of space for 4kg of hydrogen (roughly the same energy as 5 gallons of gas). That is 18 gallons of room. Let's assume that it has twice the energy efficiency of a gas-powered car, due to efficiency gains. if so, then using off the shelf technology, we can get the equivalent, using hydrogen, we can put the energy equivalent of 10 gallons of gas in the space of an 18 gallon gas tank. In addition, this is using a VERY high pressure tank that would be an absolute nightmare in a car wreck.

At this time, H2 isn't very practical. It might become practical in the near future, but I'm not going to own one until it's the only choice (or until they perfect adsorption). A H2 tank exploding will make a gas tank exploding look like nothing.

The main problem with H2 is bulk. It's the most efficient fuel by weight, but the least efficient by volume.

[MplsBison]

ubikk wrote:

The problem is that a Lithium battery large enough to power a car currently costs more than $40,000. They also have a habit running hot after a few dozen charge cycles which wastes lots of the stored energy, and some even catching fire.

I know heat has been a problem with some laptop batteries.

But I wonder if the Li Poly technology has this problem as well.

[poweRob]

perdidochas wrote: FarPastGone wrote: Quote: Water vapor is a natural greenhouse gas and accounts for the largest percentage of the greenhouse effect. Water vapor concentrations fluctuate regionally, but human activity does not directly affect water vapor concentrations except at very local scales.

In climate models an increase in atmospheric temperature caused by the greenhouse effect due to anthropogenic gases will in turn lead to an increase in the water vapor content of the troposphere, with approximately constant relative humidity. The increased water vapor in turn leads to an increase in the greenhouse effect and thus a further increase in temperature; the increase in temperature leads to still further increase in atmospheric water vapor; and the feedback cycle continues until equilibrium is reached. Thus water vapor acts as a positive feedback to the forcing provided by human-released greenhouse gases such as CO2 (but has never, so far, acted on Earth as part of a runaway feedback). Changes in the water vapor may also have indirect effects via cloud formation.

Most scientists agree that the overall effect of the direct and indirect feedbacks caused by increased water vapor content of the atmosphere significantly enhances the initial warming that caused the increase - that is, it is a strong positive feedback.([2], see B7).
Water vapor is a definite part of the greenhouse gas equation even though not under direct human control: Intergovernmental Panel on Climate Change (IPCC) TAR chapter lead author Michael Mann considers citing "the role of water vapor as a greenhouse gas" to be "extremely misleading" as water vapor can not be controlled by humans [3]; see also [4] and [5]. The IPCC discusses the water vapor feedback in more detail [6].
My question is, would water vapor not have a less adverse affect on everything then CO2?

Check the difference in climate between a rainforest at the equator and a desert at the equator. The rainforest will have the higher average temperature--the desert will at least cool down at night. Water vapor is a major greenhouse gas.

I would think that they would have lower highs and higher lows being that it would be much more difficult to change the temperature of humid air rather than dry air.

[poweRob]

GTTofAK wrote: I love how idea, put forward by morons and geniuses alike, that relesing masive amounts of one of the most destructive forces in the Universe into the atmosphere is somehow a good thing.

When all the major cities are overcast 24/7, when there is massive flooding and erosion, when there is a food shortage because all the crops have washed away, when the heat is as stifling as the rain-forest, maybe then we will learn that environmentalism is religion and not science.

Being that the exhaust is water vapor, could they build a cyclical system of catching the exhaust and chambering it then resplitting it?

[ubikk]

poweRob wrote:
Being that the exhaust is water vapor, could they build a cyclical system of catching the exhaust and chambering it then resplitting it?

I don't think the water vapor is a problem. However, your idea is interesting. they could condence the vapor (for heat in the winter if you want) and capture it in a tank. They could build solar panels into the roof of cars that split the water all day and regenerate your tank while you're inside at work. It probably wouldn't be enough to completely pay for your commute, but it would reduce how much new hydrogen you had to pay for. Multiply that by millions of cars and it all adds up.

perdidochas wrote:
For compromise, let's assume 60% as the mid-range values. This means that if you use 100 KW-hr of energy to produce hydrogen you get 60 KW-hr (potential) from that hydrogen. The average cost of electricity is about 10cents per kW-h. Hydrogen contains about 34 kW-h/kg. A kg has the energy content of a gallon of gas. To get the same energy as a gallon of gas, it would take about $3.40 in electricity at 100% efficiency. At 60% it would take $6. Let's change that to the overnight prices that some companies charge. Gulfsouth (my local power company) has a special low hour rate of 5.9 cents per kwhr. At that price, the hydrogen would cost only $3.60 per gallon.

Have you factored in the higher efficiency of fuel cells in converting the energy into motion? Also, I'm surprised electricity is that high. My rate is 5.9 cents per kwh. You could supplement that by "trickle charging" your hydrolysis with solar cells that operate all day every day.

[perdidochas]

ubikk wrote: poweRob wrote:
Being that the exhaust is water vapor, could they build a cyclical system of catching the exhaust and chambering it then resplitting it?

I don't think the water vapor is a problem. However, your idea is interesting. they could condence the vapor (for heat in the winter if you want) and capture it in a tank. They could build solar panels into the roof of cars that split the water all day and regenerate your tank while you're inside at work. It probably wouldn't be enough to completely pay for your commute, but it would reduce how much new hydrogen you had to pay for. Multiply that by millions of cars and it all adds up.

perdidochas wrote:
For compromise, let's assume 60% as the mid-range values. This means that if you use 100 KW-hr of energy to produce hydrogen you get 60 KW-hr (potential) from that hydrogen. The average cost of electricity is about 10cents per kW-h. Hydrogen contains about 34 kW-h/kg. A kg has the energy content of a gallon of gas. To get the same energy as a gallon of gas, it would take about $3.40 in electricity at 100% efficiency. At 60% it would take $6. Let's change that to the overnight prices that some companies charge. Gulfsouth (my local power company) has a special low hour rate of 5.9 cents per kwhr. At that price, the hydrogen would cost only $3.60 per gallon.

Have you factored in the higher efficiency of fuel cells in converting the energy into motion? Also, I'm surprised electricity is that high. My rate is 5.9 cents per kwh. You could supplement that by "trickle charging" your hydrolysis with solar cells that operate all day every day.

The average cost of electricity in the U.S. is 10.84 cents per KWH in June of 06. Have you checked your cost of electricity lately? You are either getting a steal, or are mislead. In terms of state averages for residential, they range from a high of 24.1 cents per KWH in Hawaii to a low of 6.4 in Idaho.


Also, until adsorption without pressurization is available, any "home" production of hydrogen is ridiculous. H2 takes up way too much space.

www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html

Also, I'm just talking internal combustion, as this is the subject of the thread.

Fuel cells can get about 80% efficiency with hydrogen, which is about the efficiency of a battery. If you add in the inefficiency of producing hydrogen, it's still not as good of a solution as an electric car (except for the possibility of being able to refuel). Personally, I wish that electric commuter cars would be produced. I'd like to have one as a second vehicle for running back and forth to work, and errands. I'd keep one gas car for trips (and hurricane evacuation). I would then sign up for my local power company's differential rates, which gives a discount for power use at night, and I would recharge the car at night.

[MplsBison]

What about the idea of replacing batteries in an electric car instead of recharging them?

IE, you drive up to a "gas station", you slide the battery pack out (or maybe it's in a tray or something), you pay the station for a new pack, put it in and you're off. The station keeps your depleted pack and recharges it.


Sort've like you can do now with propane. You take your empty tank there and grab a full one.


As far as electricity rates are going, I swear I pay less than 6 cents for a kWh. And that's not off peak or anything, just standard.