Could 'unburning' CO2 be 'the next big thing' in energy?

[GrayHare]

I don't see how solar energy becomes anymore unavailable because of this till the surface of earth is completely covered in solar panels. And by then solar energy collectors may be in space.

Since there is not an infinite supply of solar panels, each panel whose energy is being used to make ethanol is a panel not available to make energy for another purpose, such as lighting a home.

 

[meierlde]

Since there is not an infinite supply of solar panels, each panel whose energy is being used to make ethanol is a panel not available to make energy for another purpose, such as lighting a home.

Consider the issue of variable demand. Studies show that Ca for example might well overgenerate (duck curve)solar power in the PM so rather than batteries you essentially do in an inorganic way what plants do with biomass store the energy for future use.

 

[NW-Bound]

We do not need to have excess solar power in order to want a storage mechanism. Being able to store solar power will allow smoothing out the demand put on the traditional thermal generation.

Without solar storage, the thermal plants are loafing during the day, and have to ramp up to full load in the late afternoon when solar power drops off and it's still hot and AC demand is still near peak. Here, in the SW, in the summer it stays hot at higher than 100F until 9-10 PM, long after sunset.

 

[marko]

Isn't this almost the reverse of using solar power to crack H20 into burnable/usable H2? IIRC it remains inefficient for practical use.

 

[gerntz]

Since there is not an infinite supply of solar panels, each panel whose energy is being used to make ethanol is a panel not available to make energy for another purpose, such as lighting a home.

It's not a zero sum game. Yes, I too doubt there's an infinite number of solar panels but it's hardly difficult to build a 1000x more than today's number if the demand for the power is there. Net, your position is unreasonable to me.

 

[ERD50]

It's not a zero sum game. Yes, I too doubt there's an infinite number of solar panels but it's hardly difficult to build a 1000x more than today's number if the demand for the power is there. Net, your position is unreasonable to me.

Actually that would be very difficult. It would require huge amounts of energy that we don't have. A solar panel that is well situated takes about 2 years to generate enough energy to offset the energy it took to create it.

We now get ~ 1 % of kWh from solar PV now. To get to 1000x, lets estimate 100x each year for 10 years. We would need 3x the electrical energy we produce now just to make those panels and supply the power we use now. That's not feasible in any way.

Yes, you could scale up slowly, using the energy produced by the solar towards making more panels. But silicon foundries need steady, reliable power 24/7/365 - so we are back to the storage question. And it would be a slow crawl.

Certainly not "hardly difficult".

And "today's number" was produced over many years (though I think most were created in maybe the past 4-5 years?).

Note that while Elon is putting solar panels all over the Gigafactory - he isn't disconnecting from the grid - he needs that fossil fuel and nuke and hydro supply for stability.

-ERD50

 

[GrayHare]

Isn't this almost the reverse of using solar power to crack H20 into burnable/usable H2? IIRC it remains inefficient for practical use.

Exactly. For example, solar power can be used to recharge a phone directly, or it can be 1) converted to hydrocarbons (with losses due to inefficiency), then 2) those hydrocarbons can be converted back to electricity (adding more losses due to inefficiency) to recharge the same phone. The total losses are probably somewhere near 50%, meaning the conversions turn roughly half the harnessed solar energy into useless waste heat.

Solar power is not yet so abundant and inexpensive that half of it can be wasted without concern. That could change with time, or with advances in other non-hydrocarbon energy sources. For example, if fusion becomes workable and inexpensive we can power plants non-stop to suck CO2 from the air and sequester it (perhaps temporarily) in hydrocarbons.

 

[sengsational]

The paper said they converted about 65% of the electricity to the energy in the resulting ethanol. So no magic here. Laws of thermo are safe, lol!

 

[HFWR]

Actually that would be very difficult. It would require huge amounts of energy that we don't have. A solar panel that is well situated takes about 2 years to generate enough energy to offset the energy it took to create it.

We now get ~ 1 % of kWh from solar PV now. To get to 1000x, lets estimate 100x each year for 10 years. We would need 3x the electrical energy we produce now just to make those panels and supply the power we use now. That's not feasible in any way.

Yes, you could scale up slowly, using the energy produced by the solar towards making more panels. But silicon foundries need steady, reliable power 24/7/365 - so we are back to the storage question. And it would be a slow crawl.

Certainly not "hardly difficult".

And "today's number" was produced over many years (though I think most were created in maybe the past 4-5 years?).

Note that while Elon is putting solar panels all over the Gigafactory - he isn't disconnecting from the grid - he needs that fossil fuel and nuke and hydro supply for stability.

-ERD50

Not to disagree with the premise, but it takes a fair amount of energy for other forms of extractio/production.

 

[NW-Bound]

An important question that no one has asked: Is the ethanol of sufficient purity to be potable?

No doubt, there's still some CO2 left in the solution, so it is going to be a bubbly drink.

 

[ERD50]

Not to disagree with the premise, but it takes a fair amount of energy for other forms of extraction/production.

True. And if the comment like I was replying to - that "it's hardly difficult to build a 1000x more than today's number if" was made about oil, coal, hydro or wind instead of solar, we could make the same objection. It would be very difficult, and take humongous resources to expand any of our energy sources by a factor of 1000x.

Increases in intermittent renewables (wind/solar) will (at some point) need to be accompanied by increases in gas turbines to handle the troughs in production. Right now, those gas turbines fill the gap between more base load sources like coal and nuke and intermittent demand. Having an intermittent source increases that gap, and increases the need for gas turbine capacity.

Unless/until some other method of filling the gap comes along, but I don't see anything that can do this that isn't still just a dream, and/or very expensive, and/or uses lots of resources.

-ERD50

 

[samclem]

An important question that no one has asked: Is the ethanol of sufficient purity to be potable?

Moonshine from sunshine? Now >that's< a worthwhile conversion.

 

[meierlde]

An important question that no one has asked: Is the ethanol of sufficient purity to be potable?

No doubt, there's still some CO2 left in the solution, so it is going to be a bubbly drink.

Given the high taxes that potable ethanol faces in every country it will be denatured (a little methanol added) before it leaves the plant. ) Because otherwise there would be a $27/gallon federal tax rate imposed. (based upon rate of $13.50 per proof gallon which is 50% ethanol)

 

[NW-Bound]

Earlier, I said this process may not be economically amenable to build a small system in your garage. Now, if one considers the additional "incentive" as described above, it may be more attractive to the individuals who are, er, DIY green energy enthusiasts.

 

[sengsational]

Moonshine from sunshine?

They need to hire you as their marketing man!