Power to Methane

[mblakele]

Overbuilt solar and wind generation should get us to 99%+ of scenarios.

The last 2 days in CA were edge cases that will need special attention. A vast high pressure system parked itself over the state creating both record setting temperatures and virtually no wind. On top of that, smoke reduced solar production markedly. Next, our neighboring states were also undergoing the same heat wave so had less power to export to us precisely when we needed it most. So in that scenario, within 2 hours of sunset spells trouble without additional resources.

Enough batteries could deal with this situation but at current and near future costs that looks unrealistic.

On the same last 2 days there was plenty of wind power to harvest in the midwest and Texas, but how to get it here. Massive DC interconnects would take care of this. That might be a silly waste of resources for the <1% edge case days alone, but DC interconnects would pay dividends with their facilitation of regional grid efficiency gains. Each regional grid would need fewer generational facilities as a result.

[I'm replying in the power-to-methane thread because this gets into why we need to plan for days, months, or even years of reduced solar. I thought it would be a little too off-topic for the Solar PV News thread.]

Today is interesting too, at least here in the SF Bay Area. So far today my rooftop solar has produced zilch, zero, nada — because a thick pall of smoke is blocking almost all sunlight. IMO we need to plan for edge cases like this, but lasting months, or even years. Consider 1816: big impacts on agriculture of course, so we have to consider food supply; but in a decarbonized economy we also need to consider what to do about energy during a long period of reduced solar.

Year Without a Summer - Wikipedia

I think power-to-methane will be part of the answer, but there's also a case to be made for power-to-h2.

 

[nwdiver]

IMO we need to plan for edge cases like this, but lasting months, or even years.

Reminds me of a scene in Season 4 of 'The Expanse'. Plan A and B had failed and someone asks what Plan C is. Someone answers 'Plan C sounds like Everybody dies'

I think if projected peak demand on the grid is 50GW would should have 55GW of gas turbines. I don't understand the desire to eliminate gas capacity. It's cheap to build and cheap to maintain. If you don't think you'll need it for a few years then seal it and flood it with nitrogen. You can always bring it out of mothballs later.

 

[iPlug]

You raise an important case, one of the most extreme known scenarios, perhaps we could call it a <0.1% case event. Not planning for such scenarios could be disastrous.

I’m not opposed to the idea of power -> storage fuels. But overbuilding solar and wind with proper infrastructure should be able to handle an 1816-type situation.

Places in the region of a volcanic event such as this would have not just a 5-20% reduction in solar irradiance for days to months, but perhaps substantially more. For the same reason we can’t put all our chips on solar for usual weather systems and forest fires, we can’t here either.

But that’s where overbuilding and balancing with wind (on/off shore) and deep interconnects come in.

Let’s take us here in California, for example, since renewable grid progress is happening faster than most elsewhere and we are also running an unfortunate natural experiment with reduced solar irradiance from forest fires. Imagine we had deep HVDC interconnects to the midwest and Texas and in a decade or two built out offshore wind along the Pacific Northwest (the best offshore wind potential in the contiguous U.S.). Further, we overbuilt solar PV + onshore wind + offshore wind nationally and again with deep HVDC interconnects with our neighbors to the north and south such that these natural resources could power us through a record cold frigid winter with everyone on heat pumps. Using winter here since in the U.S. heating power usage is markedly higher than cooling on average.

Now run this scenario where we have an 1816-type situation, and this looks doable without any power -> fuel storage. Technology advances in the next few decades, the markets, and benevolent regulation can help decide the precise balance needed for different regions around the world.

And as nwdiver notes, gas turbines for backup should be entertained as well. In this scenario or other rare scenarios, that's not going to push us into a global warming vector if used only as emergency backup.

 

[SageBrush]

CO2 + H2 -> CH4 + H20, which doesn't balance out chemically

CO2 + 3H2 -> CH4 + H2O

 

[iPlug]

I get:

CO2 + 4H2 -> CH4 + 2H2O

 

[SageBrush]

I get:

CO2 + 4H2 -> CH4 + 2H2O

show off

 

[iPlug]

Hey, I was biochem, whatamigonna do?

 

[h8rty]

I get:

CO2 + 4H2 -> CH4 + 2H2O

I can understand the calculation by looking at it even with my purely finance background .lol

 

[ItsNotAboutTheMoney]

I can understand the calculation by looking at it even with my purely finance background .lol

Really it's just basic math to make the atoms balance.

These equations were something we did in secondary school chemistry at 15 or 16 years old, but seeing an unbalanced chemical equation is probably much more likely to trigger PTSD in a biochemistry major.

 

[Oil4AsphaultOnly]

Really it's just basic math to make the atoms balance.

These equations were something we did in secondary school chemistry at 15 or 16 years old, but seeing an unbalanced chemical equation is probably much more likely to trigger PTSD in a biochemistry major.

I'm a computer engineer. The math did not compute, ergo it bugged me.

 

[mblakele]

This machine takes office-air CO₂ and turns it into fuel

[...]

The CO2 capture technique they’re using is a scaled-down version of those designed for combustion power plants. Air goes through a chamber full of small granules that contain amines—compounds that bind with CO2 molecules. Periodically, the granules are cycled through a heating step. The temperature only needs to rise to shy of 120°C, Soletair’s Petri Laakso and Cyril Bajamundi told Ars, so steam from the local heat system and/or an electric heating element is sufficient. This makes the amine granules release the CO2 they’re holding, which accumulates in a storage tank. The granules are then ready to absorb more CO2.​

The other two-thirds of the machine, which measures about 2 meters tall, 5 meters long, and 1 meter wide, deal with turning that CO2 into a usable fuel. First, there’s an electrolyzer that splits water to make hydrogen gas. Then hydrogen is combined with CO2 in a methanation reactor to produce pure methane gas.​

The Soletair had a Bunsen burner roaring for this demonstration, and the company mentioned having run a cook stove in the office previously. (And of course there’s that espresso maker…) The viability of this whole concept pivots on the fuel providing value somewhere.​

As a CO2 filter, this unit is built to handle a standard HVAC flow of about 3 cubic meters of air per second. That can serve an office building with a few hundred occupants, Soletair says. In the company's own, smaller office, the filter was taking in air with about 500 parts per million CO2 and cutting that concentration in half.

[...]​