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Solar panels between railway tracks?

www.euronews.com Solar panels will be rolled onto Swiss railway tracks ‘like a carpet’

After long delays, the removable PV system will finally be tested on a western track next spring.

Solar panels will be rolled onto Swiss railway tracks ‘like a carpet’

I'm all for putting solar panels all over the place, but won't these get dusty and oily and need loads of cleaning after trains pass over?

Also, costing €623,000 over three years sounds rather expensive for just 100m (although that roughly equates to 11KW).

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  • As always with these fancy ideas it is a solution for something that is not a problem: We aren't even close to running out of suitable space to put solar panels. The problems for solar are usually just willingness, bureaucracy, or the electrical grid not being able to handle the additional load.

    We've also had proposals for solar bricks for paving roads/parking lots, putting the panels as dividers between highway roads. It just doesn't make sense to overcomplicate things.

    Come back once every single parking lot, large roof, unused radom patch of land, or even agricultural land (there are some interesting setups where the shade provided by solar panels is actually beneficial for the plants) is fully utilized. But chances are that at that point we already have more than enough capacity.

    • On the contrary, I'm afraid. Land is in very short supply. The issue is that even if the land is not currently developed it is doing vital stuff already. If it's used for food production, if it's a bit of forest storing massive amounts of CO2, if it's home the insects pollinating our food supply, if it's....

      Finding scrap pieces of land, like roof tops/already developed land for solar will be crucial going forward.

      • On the contrary, I’m afraid. Land is in very short supply. The issue is that even if the land is not currently developed it is doing vital stuff already. If it’s used for food production, if it’s a bit of forest storing massive amounts of CO2, if it’s home the insects pollinating our food supply, if it’s…

        I won't claim to be an expert, but I'm gonna push back on this point. Local conditions will ofc always vary, but take Germany for example, which is probably one of the more densely populated countries.

        Based on the numbers i can find anywhere from 14%-16% of our agriculturally used land is used to produce biomass. This is significantly less efficient than if even a fraction of this area were used for photvoltaics. And those rapeseed or corn monocultures probably have close to zero value for biodiversity, on the contrary i'd imagine that pesticide use will negatively impact nature overall. With solar panels on the other hand you can still use the underlying land to plant stuff like wild flowers and so on, if you wanted. There are also the already mentioned hybrid uses in agriculture where you plant crops below the panels or just use the land for grazing.

        On a side note since you mention forests. Just recently there was a number of articles on how due to their poor condition german forests have actually gone from being carbon sinks to carbon sources, releasing more CO2 than they bind.


        One more limiting factor that i forgot to mention above is lack of qualified contractors to actually build solar farms or put panels on roofs. Particularly with residential homes that seems to be another common complaint.

        • Could be a difference in availability of land, but in Sweden you'd not be granted permission for something as mundane as a solar farm if it meant taking farmland out of production.

          As for the forests... That's my greatest fear, that climate change will kill off large swathes of Oxygen producers by increasing ocean temperatures or making trees unable to thrive!

          How is agricultural land defined if it isn't used to grow biomass?

          • How is agricultural land defined if it isn’t used to grow biomass?

            I can see how i wasn't specific enough with my wording. This is what i am talking about. Basically growing plants for the purpose of energy production, rather than e.g. food or material useage.

            • Oh, i see😊 When the EED takes effect in 2025/2026 id wager the return will be better for that use than solar panels, as all public buildings will be fitted with some sort of solar capture. Wood is a great energy store, as well, which we need more of.

              Oh, and in roughly the same time frame the steps of mandatory mixing of renewable sources in central heating will start, so such agricultural land will be economically more important.

              • You could be right that that this may lead to more biomass demand due to regulations, but honestly i hope it doesn't. It's great when done with actual waste, but when done purposely it just seems much less efficient than the solar/wind alternative.

                "Growing plants -> carrying them to a biomass facility -> converting it to gas/biofuels -> using those in cars, for heating with gas or conversion to electricity in gas power plants" seems so much less efficient than just "put solar panels/wind turbine on a field -> use the electricity for EVs or heat pumps". The former has just so many extra conversion steps where energy is lost.

                Wood is a great energy store, as well, which we need more of.

                Another point that i have somewhat mixed feelings about, but it probably depends on the context.

                If we are talking use for energy production e.g. heating with wood chips/biomass, then as mentioned above it is imo only useful when done with waste (the production of which you'd ideally reduce in search for efficiency). If done by purposely growing trees to cut down and completly burn for their stored energy then logically you are at best carbon neutral (you release the CO2 that was stored), but realistically slightly worse because of transport costs and so on. Plus depending on your setup it may lead to air polution, particularly an issue if done in urban settings.

                It is however great as carbon storage and to reduce emissions when used as building material to replace something like concrete.

                • That's a whole lot of extra steps you added there. Why not simply go harvest -> burn for heat. It's not complicated and it's been done for the last 10000 years or so😊

                  As for energy storage: Electricity can not practically be stored between seasons. Wood can. So sunlight from summer will not be able to power a EV in winter, but it will heat your home. And it is a way better solution than trying to produce electricity to heat your home, even if it's just recycling CO2. At least it will not add CO2, unlike the coal that would have been used instead.

                  68 million Europeans heat their home with some kind of central heating system. It not common in west, or central Europe, but it is in the Nordics and in the eastern part. Energy forests will be important going forward.

                  • That’s a whole lot of extra steps you added there

                    I added those steps, because it is exactly what is currently done at least here in Germany and at scale. Although we might need to clarify here if we want to limit the discussion to just wood and heating specifically, or also other plants such as corn/rapeseed that are grown for biomass often converted into gas/biofuels (like with E10 petrol) to make existing technologies use less fossil fuels without need to immediately replace them.

                    And it is a way better solution than trying to produce electricity to heat your home,

                    Yes, directly heating with electricity e.g. with infrared heating panels is not the way to go and uses a ton of energy.

                    But heat pumps are a great piece of technology and pretty popular in nordic countires aswell, aren't they? With well designed ones having a COP (coefficient of performance) of 3-5. Technically they aren't creating heat, but moving it, however i think we can ignore this distinction, since both leads to the desired effect of a warm house. Added bonus that depending on the device they might also work for cooling, which will sadly become more relevant.

                    As for energy storage: Electricity can not practically be stored between seasons

                    There definitely are ways to store energy, although of course this comes at a price and the conversion steps are associated with energy losses. Besides the obvious batteries (which are improving, but admittedly probably not at a point sufficient enough to fully scale as needed), there are other options. Pumped-storage hydroelectricity is a in my opinion cool solution. You can also convert excess to hydrogen gas and store that.

                    Obviously a tree standing in the forest is stored great, but between the time to grow and sufficient supply for each season, how much space would we actually need for this solution if it were actually adpoted at scale (enough to replace existing fossile solutions)? Probably hard to estimate, but i'd imagine it would be a lot. And comercial forests like that probably aren't great for bio diversity either, and not risk free looking at the current health of existing ones and the increase in wildfires.

                    At least it will not add CO2, unlike the coal that would have been used instead.

                    That is true for sure. Although being better than coal in regard to climate impact is a low bar.

                    68 million Europeans heat their home with some kind of central heating system. It not common in west, or central Europe, but it is in the Nordics and in the eastern part.

                    I'm not certain if i understand what exactly you mean with "central heating system". Do you just mean having something like a boiler that uses e.g. gas or wood pellets in the basement? If so those are common in Germany aswell. Particularly the gas boilers are something we want to move away from (there was huge outcry when the green party of our government moved to ban new installation of those).

                    So i guess in the context of our discussion the question would be if the better replacement for those would be a wood pellet burner or something like a heat pump. And at scale my opinion is that the later is the way to go. As stated both because i doubt that wood production could scale that large and air quality is also a factor; see e.g. here. If too many people in dense residential areas would start to use them it could have health impacts. Not that we don't have those already from ICE cars, but no need to replace those as a source with something else, now that we are finally starting to get rid of them.

                    • I'm learning a lot about energy in Germany this way. Thanks! So basically farmers in Germany grow food to make fuel for cars? Like ethanol? Thats an abundance of agricultural lands!

                      Pumped hydro is great, but will only cover that much energy. Of course, there are no alps in the Nordics, but even so.

                      The batteries available today cover the need for an hour of the city they are situated in. That's not enough. So for seasonal storage you'd need to store energy as heat, as chemical energy (wood/methanol) or as H2/bio, which I think is what you describe. H2 has much of the problems of batteries in terms of storage space and the risk of fires/explosions, which limits the possibilities somewhat. But if I've understood correctly from the TEN-T directive, Germany and Switzerland has invested pretty much in H2?

                      Heat pumps are great, and are indeed well used, they run out of steam when its below -5C, which isn't rare up here. And it's seldom used in cities. Heat pumps collecting hear from the bedrock (through a drilled 100m hole in the ground) is more common, but most common is district heating. (I got the name wrong in translation earlier)

                      Instead of one boiler in every house, there is one boiler per 50-100000 inhabitants or so. Efficiency is great and heat is pipes to where it is used. When it's cold (-20 or so) those boilers go through tens of semitrucks of wood every day. And as I said, it's a fairly common set up in parts of Europe, although i understand its not common i Germany.

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