Gas from grass

[Vanden Saab]

I wasn't sure where this lived and could not find an existing thread so if it is in the wrong place or duplicate, Mods feel free to move it.
I was listening to the head honcho from Ecotricity on the radio the other morning talking about making gas from grass using some sort of anaerobic digester. It seems they have already set up a plant to provide 5,000 homes with gas using this method. The only downside seems to be that to provide enough gas for the whole country would take by my estimation 25% of all the farming land in the UK although grass can be grown on lower quality land and with the reduction in the amount of meat being eaten no doubt more grassland will be available, there can also be rotation of crops so a farm produces food in between growing grass.
I am no 'greenie' but am I missing something or could this be one of the solutions to the energy shortage and our dependence on fossil fuels which allows us to retain our gas boilers. It seems even the by-product can be used as fertilizer...

https://www.ecotricity.co.uk/our-news/2021/ecotric...

[spikeyhead]

You would need fertilizer to get good yields.

Fertilizer comes from oil.

and as for using upland grazing land, fancy using a mower on the side of a mountain.

I'm sure there are uses for this technique, but it's not without issues, and the ones above took me less than a minute to realise.

[stogbandard]

Just thinking about the amount of grass that is cut by the Council, if the clippings were collected rather than being left on the ground, how much feedstock would that provide for gas production? I’m guessing though that grass clippings left to rot reduces the need to fertilise?

[DaveGrohl]

stogbandard said:

Just thinking about the amount of grass that is cut by the Council, if the clippings were collected rather than being left on the ground, how much feedstock would that provide for gas production? I’m guessing though that grass clippings left to rot reduces the need to fertilise?

Not a lot. Clippings might seem a lot to the layman but they’re tiny compared to properly grown grass in a field.

[Evanivitch]

My food waste has been put into anaerobic digesters for over a decade and then either used for electricity or gas grid. You can also do it with sewage waste and animal waste.

I don't really see the efficiency in doing it with non-waste crop material.

Grass clippings possibly, but often takes.more energy to recover grass from many dispersed areas in a maintenance context.

spikeyhead said:

Fertilizer comes from oil.

That's a lie.

Fertiliser can be made using methane, that's where the Hydrogen is sourced. It can also be made using hydrogen from other sources and combined with atmospheric Nitrogen.

[DaveGrohl]

Vanden Saab said:

I wasn't sure where this lived and could not find an existing thread so if it is in the wrong place or duplicate, Mods feel free to move it.
I was listening to the head honcho from Ecotricity on the radio the other morning talking about making gas from grass using some sort of anaerobic digester. It seems they have already set up a plant to provide 5,000 homes with gas using this method. The only downside seems to be that to provide enough gas for the whole country would take by my estimation 25% of all the farming land in the UK although grass can be grown on lower quality land and with the reduction in the amount of meat being eaten no doubt more grassland will be available, there can also be rotation of crops so a farm produces food in between growing grass.
I am no 'greenie' but am I missing something or could this be one of the solutions to the energy shortage and our dependence on fossil fuels which allows us to retain our gas boilers. It seems even the by-product can be used as fertilizer...

https://www.ecotricity.co.uk/our-news/2021/ecotric...

Where to start with this? Dale Vince has a certain set of views which he wants to force on the world but mainly so that he can profit from them.

Digesters have existed for decades in some countries. They’re a very good idea and a good way to turn waste that would otherwise cause several issues into usable energy. If you’re going to use farmed crops however you certainly wouldn’t use grass because of its low gas yield compared to crops like maize, hybrid rye, wheat etc. Our govt has stopped all future digesters from using these crops, any new digesters must use different feedstocks like food waste (which is a good thing).

Another problem for Dale is that there is AFAIUI more fossil fuel carbon emitted by the operations before the crop enters the digester than is saved by the digester at the end. There are all sorts of other "issues" around the assumptions and beliefs that Dale tells the public which aren’t really connected with reality. He is of course free to use his money as he sees fit. But please don’t think that Dale’s ideas wrt to digesters are an answer to anything.

[DaveGrohl]

Evanivitch said:

My food waste has been put into anaerobic digesters for over a decade and then either used for electricity or gas grid. You can also do it with sewage waste and animal waste.

I don't really see the efficiency in doing it with non-waste crop material.

Grass clippings possibly, but often takes.more energy to recover grass from many dispersed areas in a maintenance context.

spikeyhead said:

Fertilizer comes from oil.

That's a lie.

Fertiliser can be made using methane, that's where the Hydrogen is sourced. It can also be made using hydrogen from other sources and combined with atmospheric Nitrogen.

Haber Bosch process which uses natural gas (methane). That’s the nitrogen part. Have you seen the price of fert lately?

[Mr.Chips]

We used to used grass clippings to make biogas generators, when I was teaching. Some would make next to nothing, others would get the conditions just right and get quite a few millilitres.

[skwdenyer]

DaveGrohl said:

Evanivitch said:

My food waste has been put into anaerobic digesters for over a decade and then either used for electricity or gas grid. You can also do it with sewage waste and animal waste.

I don't really see the efficiency in doing it with non-waste crop material.

Grass clippings possibly, but often takes.more energy to recover grass from many dispersed areas in a maintenance context.

spikeyhead said:

Fertilizer comes from oil.

That's a lie.

Fertiliser can be made using methane, that's where the Hydrogen is sourced. It can also be made using hydrogen from other sources and combined with atmospheric Nitrogen.

Haber Bosch process which uses natural gas (methane). That’s the nitrogen part. Have you seen the price of fert lately?

It is possible to synthesis methane from hydrogen and CO2. If you can use renewable energy (eg solar) for H production, and sequester CO2 from the atmosphere, you can create efficient, carbon-neutral methane.

The tech is close to production-ready. I’m hoping the current situation with Russia will accelerate the availability of investment capital to get it over the line.

[Evanivitch]

skwdenyer said:

It is possible to synthesis methane from hydrogen and CO2. If you can use renewable energy (eg solar) for H production, and sequester CO2 from the atmosphere, you can create efficient, carbon-neutral methane.

The tech is close to production-ready. I’m hoping the current situation with Russia will accelerate the availability of investment capital to get it over the line.

There's nothing efficient about doing it.

[skwdenyer]

Evanivitch said:

skwdenyer said:

It is possible to synthesis methane from hydrogen and CO2. If you can use renewable energy (eg solar) for H production, and sequester CO2 from the atmosphere, you can create efficient, carbon-neutral methane.

The tech is close to production-ready. I’m hoping the current situation with Russia will accelerate the availability of investment capital to get it over the line.

There's nothing efficient about doing it.

I disagree. No need to transport raw materials to the production site. Energy generated on-site, so primarily capex rather than running costs. No downstream carbon capture required as the atmospheric carbon sink does that for us - we just need to balance inputs and outputs.

We have to change our mindset. Hydrocarbons are only “efficient” because we look only at the energy input of extraction, not the embodied energy of the raw material or the environmental costs. We can’t do that any more.

If we synthesise methane using grid energy, that would be poor. But that’s not what I’m suggesting.

If we do nothing, agriculture will be in trouble. What do you suggest instead?

[Evanivitch]

skwdenyer said:

I disagree. No need to transport raw materials to the production site. Energy generated on-site, so primarily capex rather than running costs. No downstream carbon capture required as the atmospheric carbon sink does that for us - we just need to balance inputs and outputs.

Using solar means you're not going to have a constant production process because of daily and seasonal variations. So you're going to need to have a variety of energy sources to power it.

And then you still need a means to export the generated fuel from the site. As a general rule areas ideal for renewable energy siting aren't heavy population areas.

There's still a carbon cost to renewables generation. And you'd need a massive amount to support large scale synthetic fuel generation.

And then what are you going to do with these synthetic fuels? Burn them!? Well that's a 40% efficient process at best.

skwdenyer said:

We have to change our mindset. Hydrocarbons are only “efficient” because we look only at the energy input of extraction, not the embodied energy of the raw material or the environmental costs. We can’t do that any more.

If we synthesise methane using grid energy, that would be poor. But that’s not what I’m suggesting.

If we do nothing, agriculture will be in trouble. What do you suggest instead?

I've not said hydrocarbons are efficient. They're not.

You should also consider the environmental impacts of synthetic fuels. It's still combustion, there's still NOx and particulates. There's still the risk of spillage and contamination. You still need engines, coolants, lubricants, catalysts, particulate filters.

All in all, if agriculture needs to keep using liquid fuels I'd rather they carried on burning fossil fuels TBH, and instead we used the huge amount of energy that you propose to be used on synthetic fuels to instead be used on low-carbon fertiliser, and steel and heating products.

[C n C]

skwdenyer said:

Evanivitch said:

skwdenyer said:

It is possible to synthesis methane from hydrogen and CO2. If you can use renewable energy (eg solar) for H production, and sequester CO2 from the atmosphere, you can create efficient, carbon-neutral methane.

The tech is close to production-ready. I’m hoping the current situation with Russia will accelerate the availability of investment capital to get it over the line.

There's nothing efficient about doing it.

I disagree. No need to transport raw materials to the production site. Energy generated on-site, so primarily capex rather than running costs. No downstream carbon capture required as the atmospheric carbon sink does that for us - we just need to balance inputs and outputs.

We have to change our mindset. Hydrocarbons are only “efficient” because we look only at the energy input of extraction, not the embodied energy of the raw material or the environmental costs. We can’t do that any more.

If we synthesise methane using grid energy, that would be poor. But that’s not what I’m suggesting.

If we do nothing, agriculture will be in trouble. What do you suggest instead?

Regarding the bold above, why would you bother with the methane production. If you are looking to produce a gas and then burn it, and If you're already producing hydrogen, then why not just use the hydrogen (which only produces water as a result of its combustion)?

[Evanivitch]

C n C said:

Regarding the bold above, why would you bother with the methane production. If you are looking to produce a gas and then burn it, and If you're already producing hydrogen, then why not just use the hydrogen (which only produces water as a result of its combustion)?

I would expect because we already have significant methane infrastructure and it's significantly easier to handle and maintain energy density.

[Toaster]

DaveGrohl said:

Where to start with this? Dale Vince has a certain set of views which he wants to force on the world but mainly so that he can profit from them.

Digesters have existed for decades in some countries. They’re a very good idea and a good way to turn waste that would otherwise cause several issues into usable energy. If you’re going to use farmed crops however you certainly wouldn’t use grass because of its low gas yield compared to crops like maize, hybrid rye, wheat etc. Our govt has stopped all future digesters from using these crops, any new digesters must use different feedstocks like food waste (which is a good thing).

Another problem for Dale is that there is AFAIUI more fossil fuel carbon emitted by the operations before the crop enters the digester than is saved by the digester at the end. There are all sorts of other "issues" around the assumptions and beliefs that Dale tells the public which aren’t really connected with reality. He is of course free to use his money as he sees fit. But please don’t think that Dale’s ideas wrt to digesters are an answer to anything.

Dale does have views along with investing his own money into producing a green energy product, I suspect he would be the first to acknowledge that any fossil fuel used in the production of any green energy has to be phased out. Had the energy industry invested much earlier in wind, solar and digesters we may not have the energy crises we have today. Dale is not the problem the petrochemical industry and government policy is......

[Evanivitch]

Toaster said:

Dale does have views along with investing his own money into producing a green energy product, I suspect he would be the first to acknowledge that any fossil fuel used in the production of any green energy has to be phased out. Had the energy industry invested much earlier in wind, solar and digesters we may not have the energy crises we have today. Dale is not the problem the petrochemical industry and government policy is......

Digester are great when fed with waste from domestic, commercial and sewage. But for that reason it's very difficult to scale them. There's still lots to be done, in 2020 there were 13 million households that didn't have seperate food waste collection. They weren't is Wales...


Dale isn't right on everything for sure. But things like the Electric Highway and large-scale wooden construction are things he has done quite well with. He'll still turn up to a 'green' event in a 730d though... Don't think he's ever like Tesla...

[skwdenyer]

Evanivitch said:

skwdenyer said:

I disagree. No need to transport raw materials to the production site. Energy generated on-site, so primarily capex rather than running costs. No downstream carbon capture required as the atmospheric carbon sink does that for us - we just need to balance inputs and outputs.

Using solar means you're not going to have a constant production process because of daily and seasonal variations. So you're going to need to have a variety of energy sources to power it.

And then you still need a means to export the generated fuel from the site. As a general rule areas ideal for renewable energy siting aren't heavy population areas.

There's still a carbon cost to renewables generation. And you'd need a massive amount to support large scale synthetic fuel generation.

And then what are you going to do with these synthetic fuels? Burn them!? Well that's a 40% efficient process at best.

skwdenyer said:

We have to change our mindset. Hydrocarbons are only “efficient” because we look only at the energy input of extraction, not the embodied energy of the raw material or the environmental costs. We can’t do that any more.

If we synthesise methane using grid energy, that would be poor. But that’s not what I’m suggesting.

If we do nothing, agriculture will be in trouble. What do you suggest instead?

I've not said hydrocarbons are efficient. They're not.

You should also consider the environmental impacts of synthetic fuels. It's still combustion, there's still NOx and particulates. There's still the risk of spillage and contamination. You still need engines, coolants, lubricants, catalysts, particulate filters.

All in all, if agriculture needs to keep using liquid fuels I'd rather they carried on burning fossil fuels TBH, and instead we used the huge amount of energy that you propose to be used on synthetic fuels to instead be used on low-carbon fertiliser, and steel and heating products.

We were talking about fertiliser production. Right now, a lot of fertiliser is produced from natural methane. If we want to reduce our dependence upon fossil fuels whilst leveraging the existing supply chain for methane-based fertiliser, we need an alternate source of methane.

I didn't say solar; I said renewables. There are many ways to do that. I didn't say it was easy, nor cheap - but the cost is primarily capex. It is precisely the sort of thing national governments could invest in, to provide a secure and cost-effective source of fertiliser feedstock for their national agriculture.

You say there's still a carbon cost to renewables generation. There is, but we need to tackle that come what may. We've no choice.

As regards continuing to rely upon fossil fuels, that's going to be politically as well as environmentally unviable. We simply can't allow the future to be held hostage by the regimes who happen to have access to such fuels.

[Evanivitch]

skwdenyer said:

We were talking about fertiliser production. Right now, a lot of fertiliser is produced from natural methane. If we want to reduce our dependence upon fossil fuels whilst leveraging the existing supply chain for methane-based fertiliser, we need an alternate source of methane.

Then there's zero need to make synthetic methane. Methane is just the commercially viable hydrogen carrier we use today. We can easily produce hydrogen using renewables. There's no need to consume further energy making methane as part of fertilizer production.

[skwdenyer]

Evanivitch said:

skwdenyer said:

We were talking about fertiliser production. Right now, a lot of fertiliser is produced from natural methane. If we want to reduce our dependence upon fossil fuels whilst leveraging the existing supply chain for methane-based fertiliser, we need an alternate source of methane.

Then there's zero need to make synthetic methane. Methane is just the commercially viable hydrogen carrier we use today. We can easily produce hydrogen using renewables. There's no need to consume further energy making methane as part of fertilizer production.

Yes and no Methane plugs into existing methane-based processes. It can be distributed under normal temperatures and pressures using existing infrastructure. Unless you site your hydrogen plant next to a fertiliser plant, moving hydrogen around represents rather the burden, and potentially requires re-tooling your fertiliser production.

[Evanivitch]

skwdenyer said:

Evanivitch said:

skwdenyer said:

We were talking about fertiliser production. Right now, a lot of fertiliser is produced from natural methane. If we want to reduce our dependence upon fossil fuels whilst leveraging the existing supply chain for methane-based fertiliser, we need an alternate source of methane.

Then there's zero need to make synthetic methane. Methane is just the commercially viable hydrogen carrier we use today. We can easily produce hydrogen using renewables. There's no need to consume further energy making methane as part of fertilizer production.

Yes and no Methane plugs into existing methane-based processes. It can be distributed under normal temperatures and pressures using existing infrastructure. Unless you site your hydrogen plant next to a fertiliser plant, moving hydrogen around represents rather the burden, and potentially requires re-tooling your fertiliser production.

Manufacturing hydrogen from hydrolysis is remarkably easier than steam reforming....