Suramya's Blog : Welcome to my crazy life…

When I first read that Finland has inaugurated world’s largest sand battery, the fist question I had was “What is a sand battery?”. Is it a new battery that uses Sand somehow instead of Lithium-Ion or similar tech to product power? Then I read up more about it and the answer is even cooler. As per Wikipedia, this is a Thermal battery, using sand as a heat storage medium to power generators using stored power. The following diagram has a good explanation on how the tech works:

1. Electricity is generated by Wind Turbines or Solar (or other power generation sources)
2. 30% of the energy is used to power the local infrastructure
3. The remaining 70% is stored in the Sand battery by heating the sand up to 600-1000 Degree C.
4. The stored energy is used to generate power or provide heating during winter months or at night.

The advantage of using Sand for storing heat is that it is cheap and a very effective medium for retaining heat over long periods of time. Once the energy is stored as heat it can then be used to heat homes, or to provide hot steam and high temperature process heat to industries that are often fossil-fuel dependent.

Polar Night Energy said the battery has met expectations in its first months and exceeded guaranteed efficiency targets. It has replaced the area’s old woodchip plant all summer.

A sand battery stores clean electricity as heat in sand or other solid materials. The Pornainen unit stands nearly 13 meters tall and 15 meters wide, delivers 1 MW of thermal power, offers 100 MWh of storage, and contains roughly 2,000 tons of crushed soapstone.

Polar Night Energy said the battery can participate in electricity reserve markets, charging according to electricity prices and Fingrid’s reserve market signals. Its storage capacity allows consumption to be optimized over days or weeks and helps balance the grid.

Finnish Minister of the Environment Sari Multala said thermal storage improves energy system flexibility and reduces industrial emissions.

I can see this tech (once it matures) being used in areas that have a large temperature fluctuation on a daily or yearly basis like deserts. During the day we can charge the reservoir up and then use it at night to heat homes. In a way it is a larger application of how the traditional homes in desert areas are built using mud.

Source: @janrosenow.bsky.social

– Suramya

As the world is trying to move away from fossil fuels more research is being done on other sources of power generation. Osmotic power generation is one of new latest technologies on the block and Japan has launched its first osmotic power plant, making it the second Osmotic power plant in existence worldwide. This was the first time I heard about Osmotic power so did a bit of research on it as it sounded shady, turns out that it is actually a thing and under experimentation world wide. The Japanese plant is expected to generate about 880,000 kilowatt hours of electricity each year which is the equivalent of powering about 220 Japanese households.

Osmotic energy is a lesser-known form of energy generation that captures the energy generated from the natural salinity gradient between freshwater and saltwater.

This type of energy – also known as “blue energy” – is generated through the natural phenomenon of osmosis. This occurs when water moves from an area of lower solute concentration (freshwater) to an area of higher solute concentration (saltwater) across a semipermeable membrane. When freshwater and seawater meet, a natural gradient in salinity is created, prompting ions to migrate from the saltier side to the less salty side in pursuit of equilibrium. The movement of water and ions generates a pressure differential that can be harnessed to produce electricity. The process resembles a “silent lightning strike” occurring continuously at the confluence of rivers and oceans.

The concept has been around since the early 1970’s but due to the inefficiency of the membranes required, implementation was considered impractical but advances in membrane and pump technology are reducing these problems. That said this technology is still not as scalable as other renewable technologies (as of now) so I doubt that we will start seeing Osmotic power plants being setup all over the place that soon. One option would be to put these plants up near water desalination plants so that the waste water from those plants can be used to generate electricity more efficiently in the Osmotic power plant (With the increased salinity of water used, the plant is more efficient.

It’s nice to read about all these efforts to reduce our dependency of fossil fuels.

Source: The Guardian: Japan has opened its first osmotic power plant – so what is it and how does it work?

– Suramya

India is working hard towards reducing our dependency on fossil fuels and moving to alternative/renewable power source. As part of this effort we have been aggressively installing more and more solar plants across India. The Delhi Metro installed India’s First Vertical Bi-Facial Solar Plant last week. The new 50kW vertical solar plant at Okhla Vihar Metro Station features bi-facial panels that capture sunlight from both sides, enhancing energy generation efficiency.

India added a record 25 GW solar capacity in 2024 which is a 204% jump from previous year. Part of it was due to the commissioning of projects that supposed to go online in 2023 but got delayed and went live in 2024. Even with that being the case this is a great milestone and the total generation capacity for India has topped 100GW, putting India in the top 3 countries worldwide for Solar power production.

Solar and other green energy sources are awesome. They allow you to generate power without creating harmful byproducts like coal or petrol based energy generators do. Unfortunately this means that Coal and Oil industries are completely against them and constantly create posts, advertisements and ‘research’ that show how bad the renewable energy sources are. Basically it is a constant bombardment of FUD (Fear Uncertainty & Doubt) to cause people to distrust the technology.

The following comics keep showing up in my feed and it is typical of how people portray green power and electric vehicles. According to them there is no point in getting an electric car or a green power alternative because they all use coal/gas fueled power plants in the background and that can’t be further from the truth.

In fact, the main reason ‘people’ (read oil/coal companies) don’t want us to switch to renewable is explained very well by the following comic:

Solar Power isn’t feasible because we can’t own the sun

One (valid) cause for concern is that it is expensive to setup, which is true but not the whole story. We setup a solar power plant at my parents place in Delhi and while it does take up space it is not as bad as people make it sound. One set of panels actually makes a great share in front of the room on the roof, the other is on top of that room so helps keep the temperature in that room down and with the temperature in Delhi hitting 52.8 Deg C it is not a small consideration.

The setup we have is for a 10kwa solar panels and it costed us ~4,50,000 lac. Based on our regular usage we will recover the cost in about 4 1/2 years (its been almost 4 years since we set it up).

There is a pretty good subsidy for Solar being offered by the Indian government at the central level so it is a great time to setup a Solar power plan wherever you can. My cousin has also set it up in UP and it is a big help over there because they are no longer dependent on the power company for power.

With the new more powerful panels nowadays the time taken to recover the cost of the setup is down to a few years. To be fair, the process of generating the solar panel does create waste that is a pollutant but that is minuscule compared to the waste generated by a coal/gas power plant.

– Suramya

Having drinking water is a problem in a lot of places on Earth due to various reasons. One of the solutions for this is to extract drinking water out of sea water/salty water. Unfortunately, the traditional methods of doing this require a lot of power and that causes other issues. Plus, that means that we can’t setup the desalination plants in locations where they are most needed as these locations don’t usually have reliable power either. One solution is to use renewable energy such as Solar to power these plants but the traditional setups expect constant power levels which isn’t always possible due to weather conditions.

Around a 100 years ago we developed reverse osmosis and electrodialysis, which are two membrane-based desalination technologies. Reverse osmosis requires a lot of pre-treatment and thus not sustainable everywhere, which is why MIT researchers led by Jonathan Bessette decided to go with electrodialysis instead.

What makes their approach really interesting is that their setup runs on renewable energy (Solar Power) and automatically adjusts the quantity of water being processed depending on the weather conditions instead of expecting constant power levels. So if it was a sunny day with clear skies then the setup would process more water, and if it was cloudy the quantity being processed would reduce automatically.

The two most important parameters in electrodialysis desalination are the flow rate of the water and the power you apply to the electrodes. To make the process efficient, you need to match those two. The advantage of electrodialysis is that it can operate at different power levels. When you have more available power, you can just pump more water through the system. When you have less power, you can slow the system down by reducing the water flow rate. You’ll produce less freshwater, but you won’t break anything this way.

Bessette’s team simplified the control down to two feedback loops. The first outer loop was tracking the power coming from the solar panels. On a sunny day, when the panels generated plenty of power, it fed more water into the system; when there was less power, it fed less water. The second inner loop tracked flow rate. When the flow rate was high, it applied more power to the electrodes; when it was low, it applied less power. The trick was to apply maximum available power while avoiding splitting the water into hydrogen and oxygen.

The prototype unit they setup was the size of a shipping container and over the 6 months trial period it desalinated around 5,000 liters of water per day—enough for a community of roughly 2,000 people. The team is now working on productionalizing the solution and selling it commercially.

Their work was published in Nature: Direct-drive photovoltaic electrodialysis via flow-commanded current control, earlier this month.

Looking forward to people building on top of this effort and having such units available for purchase.

Source: Mastodon: https://mstdn.social/@kevinrns/113341185649409458