CliDemy - The Climate Academy - climate education & skilling

A Minute for Climate

What’s with Peak Load?

All electrons are same, aren’t they?

What a strange question!

There is a reason for this.

And that has got to do with what is called peak load.

You see, if the entire world uses electricity at a constant rate, without fluctuations, things could be a lot quieter at power plants.

But that’s not the way how electricity is consumed.

There are times when a city could be using a lot less electricity – less us say on a cool Sunday evening when no one really needs an air conditioner – and others when the same city could be using a lot more – imagine a hot summer afternoon when all the factories are also humming!

The loads on power plants during times when the demand for power peaks are called peak loads.

The question for power plants is: For which scenario do they plan their capacity for? The obvious answer is: They have to plan it for the scenario when a lot more electricity is used – in other words, for peak loads.

But the challenge is, when the city uses a lot less power, a large part of the capacity will remain idle!

Many power plants overcome this by having a baseload plant that supplies a certain amount of electricity and a peaker plant that kicks in when the electricity demand increases significantly.

But the electricity from peaker plants are far more expensive to generate for the power plants compared to the baseload electricity.

Introduction of renewable power sources such as solar could in some cases take care of the extra electricity required during peak periods – if they happen when the sun is shining bright – and this is called Peak Shaving. Use of batteries is another – though expensive – way to take of sudden increases in load.

A Minute for Climate

The surging interest in Napier Grass

Napier grass, also called Elephant grass and Uganda grass, is a species of perennial tropical grass, a native of the African grasslands. As it has low water and nutrient requirements, it can be grown in many areas with ease.

It has been used as a fodder crop for silage in many tropical and subtropical countries.

But all these still do not explain why many regions in the world are showing an increasing interest in this crop.

The main reason behind the enhanced interest is its potential to be used as a biofuel feedstock.

In the words of the US Dept. of Agriculture, “Napier grass, otherwise known as elephant grass, has the highest biomass productivity of any grass that has been tested for biofuel feedstock cropping in the southeastern United States.”

Given its high cellulose content (35-40%), drought tolerance, water use efficiency and high yields per units area, it appears to be an ideal source to make ethanol, a biofuel that can be blended with gasoline (petrol) to reduce the overall CO2 emissions from transport. The other sources of ethanol – corn, sugarcane – all have high water and land area requirements, and also present the Food vs. Fuel dilemma.

Recent technology advances are also enabling the production of biogas and further down renewable natural gas from Napier grass.

Given all the above, expect to see the simple Napier grass in many more places than you would have so far.

A Minute for Climate

Sand Battery

Who would have thought that sand – yes, sand – can be used as a battery!

But that is precisely what some companies have succeeded in doing.

How do sand batteries work?

Firstly, a battery does not always mean that it stores electricity the way the conventional batteries do – which is in an electrochemical form.

Electricity can also be stored as heat – and that is what sand batteries do.

Sand can retain heat quite well, and for a long time – for months if you wish! By converting electricity to heat, and then by storing the heat in a mixture that comprises mostly sand, you get a sand battery.

The sand in these “batteries” can reach a temperature of 600 degrees.

How do we recover the energy back? In many cases, the stored heat can be used for a variety of heating purposes. It is also possible to use the stored heat to generate electricity back again using advanced turbine-based power generation solutions.

Sand batteries could find near term applications for storing renewable energy such as solar or wind power, providing an attractive avenue of storing excess energy generated from these infirm power sources.

A Minute for Climate

Renewable Natural Gas

Natural gas is a fossil fuel, extracted from under the ground.

While natural gas emits CO2 when combusted for heating or power generation, its CO2 emissions are only about 50% that of coal and about 80% that of gasoline or diesel.

This is why natural gas is considered to be a transition fuel on the journey to Net Zero – because it can replace coal or oil but at much lower emissions.

Recent developments have made natural gas an even more attractive low carbon fuel, and this is through the production of renewable natural gas.

What is renewable natural gas?

Renewable natural gas is methane derived from biogas. Biogas itself is derived from renewable or sustainable sources such as organic waste or plant waste.

Biogas comprises about 50% methane and 45% CO2 (by volume). When one removes CO2 and other minor components such as H2S, what remains is methane – the same as natural gas.

Thus, methane derived from biogas is termed renewable natural gas and is becoming an important component in the overall biofuels mix of many countries.

A Minute for Climate

Coal is not dead – yet

Coal is thought to be one of the key villains in our fight against climate change.

And for a reason – almost 30% of all the global CO2 emissions come from power generation, and coal-based power plants contribute a dominant share of these emissions.

While countries are trying to cut down on coal-based power and increase power from renewable energy sources such as solar and wind, it is not that easy.

Countries such as India, China and South Africa still rely significantly on coal for their power generation. These cannot be turned off easily. In fact, a recent draft plan from the Indian government expects a significant addition to India’s coal power plant capacity over the next ten years.

While coal will eventually go away, expect it to linger around for decades.

What this implies is that it is important to figure out ways by which coal power plants can be made low carbon – be it through high operational efficiencies, partial blending of biomass with coal, or through capture & storage of CO2 emissions from these plants.

A Minute for Climate

Colours of hydrogen

Hydrogen is an invisible gas. That’s what chemistry taught us.

But now we are told there are different colours of hydrogen – grey, blue and green in particular.

What’s going on?

Well, the above colours are applied depending on how the gas is produced.

Grey hydrogen refers to hydrogen produced from natural gas – this process emits CO2 and thus the rather unimpressive color grey.

Blue hydrogen is also produced from natural gas but here, the CO2 emissions are captured and stored – so a more endearing colour.

Green hydrogen, the one in the limelight now, typically refers to hydrogen produced by splitting water through electrolysis – which is in turn powered by renewable sources of electricity such as solar or wind energy.

Green hydrogen carries a very small production carbon footprint compared to that for grey or blue hydrogen, and is hence expected to be an important driver for a low carbon economy.

A Minute for Climate

Blue Carbon!

CO2 has no colour, but the world uses a term blue carbon.

What is blue carbon?

Blue carbon refers to the CO2 sequestered by the marine ecosystem, especially by coastal ecosystems comprising mangrove forests, tidal marshes and seagrass meadows.

Why is blue carbon important in the context of climate action?

Estimates show that blue carbon ecosystems can store twice the amount of carbon per hectare and sequester it as much as 30 times faster than terrestrial forests. Terrific – implies that blue carbon ecosystems have the potential to provide decarbonization on scale, and much faster than terrestrial trees.

While the carbon capture potential for blue carbon ecosystems is excellent news, if these ecosystems are not preserved well, they could end up emitting back the massive amounts of CO2 they have captured!

It is thus critical to understand more about this important ecosystem and ensure that we preserve it and enable it to flourish further.

A Minute for Climate

Can fertilizer overuse emit greenhouse gases?

Most of the talk around greenhouse gases is about CO2 and methane (CH4).

Did you know that using too much fertilizers can emit a different greenhouse gas?


In addition to CO2 & CH4, another important greenhouse gas is Nitrous Oxide (N2O) – yes, what we call the laughing gas. Fertilizers contain nitrogen, and overapplication of fertilizers can lead to excess nitrogen being converted to N2O and released to the atmosphere.

The world emits only about 12 million tons of N2O per year. This is quite small compared to 35 billion tons of CO2 per annum. But hold on, the global warming potential is about 275 times that of CO2, which translates the total N2O emissions to a bit over 3 billion tons of CO2 equivalent!

This is why methods such as precision farming that use only the required amount of fertilizers could play a significant role in climate action – they not only reduce the costs of fertilizers, but also reduce greenhouse gas emissions from agriculture.

A Minute for Climate

Data centers are huge energy guzzlers mainly because…

With the fast growth of Internet and cloud services, the need for more and larger data centers is also increasing globally.

Data centers already consume significant amounts of electricity, and thus are responsible for significant amounts of CO2 emissions. Globally, about 600 million tons of CO2 emissions are contributed from data center operations alone, about 2% of total CO2 emissions.

Why do data centers require so much electricity? While part of the electricity is needed for operating the servers, a good portion – close to 50% in some cases – of the energy is used for cooling the servers.

Thus, data center cooling alone could be contributing to about 300 million tons of CO2 emissions worldwide – more than the annual emissions of about 90% countries in the world.

So, efficient methods that can halve the energy required to cool data center servers could save 150 million tons of CO2 emissions every year!

A Minute for Climate

Food waste => Insects = > Animal feed

The world wastes a lot of food.

Make that a real lot – about 1 billion tons of food is wasted every year globally.

Digest that for a moment.

Can such a large amount of food waste be turned into something valuable?

How about converting food waste into food – for animals?

This is precisely what many innovative startups around the world are trying.

Insects such as the Black Soldier Fly feed on food waste. These insects are also rich in protein.

Combine the above two facts and voila! – feed the food waste to such insects and use these protein-rich insects to replace animal feed such as fish meal.

By doing this, you are sustainably disposing food waste while getting a low carbon, high protein animal feed!

A Minute for Climate

Can we store energy for months together?

Most batteries are capable of storing energy efficiently only for a few hours.

But there are situations where energy needs to be stored for months together.

Take a city in a cold region in Europe. The city might want to capture the heat from sunlight during the summer and use that for home or district heating in winter. But winter could be six months away from the time the unit of energy was captured from sunlight.

Are there systems that can store the energy for many months together?

Yes. While different solutions are emerging for medium and long term energy storage, it is already proven that underground energy storage systems can store heat efficiently long enough to last for the next season. These underground locations might be in the form of boreholes, caverns, pits or aquifers.

A community in Alberta, Canada has seen significant success in the use of underground heat storage between seasons. The underground storage of heat captured during summer is fulfilling more than 90% of each home’s space heating requirements in winter, resulting in reduced use of fossil fuels.

A Minute for Climate

Photosynthetic efficiency of plants is just…

While plants do an admirable job of converting sunlight and CO2 into food and fibers that we all use, what is the efficiency with which they convert sunlight into chemicals?

Surprisingly, it is terribly low.

For most plants, the photosynthetic efficiency is in the 1-2% range – that is, only about 1/50th of the total energy from sunlight falling on the plant is converted into useful energy or materials.

What can we do about this rather unimpressive fact?

We can try to figure out if there are ways plants could be nudged to have higher conversion efficiencies – genetic modifications perhaps?

Another possibility is to consider if we can design equipment that can convert sunlight to energy or materials at much higher efficiencies.

We have a live example: Solar photovoltaic cells already convert sunlight to electricity at over 20% efficiencies – that’s TEN TIMES higher than that of plants.

Going beyond physics, scientists are also trying microbiological methods – for instance, they are exploring if a broth of CO2, water and micro-organisms could use sunlight to produce chemicals, food or fuels, but far more efficiently than plants.

A Minute for Climate

40% efficiency from solar panels – possible?

Solar power plants use photovoltaic cells whose efficiencies are currently in the 20-23% range.

In fact, there is even a theoretical upper limit of about 33.2% for the conventional “single-junction” solar cells – called the Shockley–Queisser limit.

So how can some reputed research organizations claim that they have been able to reach efficiencies of much higher than 40%, even around 45%?

It is possible because they are using not a single-junction solar cell, but a multi-junction solar cell in which there is more than one p-n junction (a critical component) made of different semiconductor materials.

As the number of p-n junctions increase, the maximum possible theoretical efficiency increases too.

For efficiencies as high as 40%, in addition to using multi-junction solar cells, it is also important to have the sunlight falling on the cells to be concentrated through the use of mirrors or lenses.

In summary, generating efficiencies much higher than 25% from conventional solar cells is very difficult. For solar cells to have efficiencies beyond 30%, different cell architectures, as well as additional equipment to concentrate sunlight, will need to be used.

A Minute for Climate

Can we store heat in salt?

Is it possible to store heat in a salt?

What a strange question!

Even more strangely, the answer is: Yes.

Sodium nitrate, for example, is used to store heat in what are called concentrated solar thermal applications, in which temperatures can reach above 400 degrees C.

Why is a material like sodium nitrate used for storing heat? Because these fall under the category of “phase change materials” or PCM for short.

PCMs typically absorb or release large amounts of heat with high efficiencies when they change from one phase to another – absorb heat when they change from solid to liquid and release heat during the reverse phenomenon.

PCMs such as sodium nitrate thus are promising materials of choice for energy storage.

A Minute for Climate

Are some of our food made from petroleum?

If someone told you that some of the ingredients in the food you eat or beverages you drink came from petroleum, you will not be amused.

But it is true. Many food, beverage and even nutraceutical ingredients are still derived from chemicals which originate with petroleum.

For instance, many of the colorants used in our foods, beverages, candies and ice creams are still derived ultimately from crude oil. While in most countries these have been approved by the corresponding food safety agencies, the fact that they ultimately rely on a fossil fuel is quite a concern.

Are there natural alternatives that can replace these? In many cases, natural substitutes are available for the synthetic food ingredients, but the natural variants are more expensive to produce.

But as the world moves towards a low carbon future, perhaps it is time that the food industry put a high price on the use of fossil based materials and encouraged a shift to natural, plant-based feedstock.

A Minute for Climate

2023 – International Year of Millets

Globally, about 30 million tons of millets are produced every year. Over 500 million tons of rice are produced.

That is: Over 15 tons of rice are produced for every ton of millet.

But it perhaps should be the other way round.

Millets are more nutritious than rice – they have higher proteins and fiber content

Millets are more healthy for the environment – they require only a fraction of water to cultivate compared to that for rice.

Good for human health. Good for climate.

It is indeed thus great news that 2023 has been nominated by the United Nations as the International Year of Millets.

Let’s hope this helps a worthy crop get the attention that it so richly deserves.

A Minute for Climate

Can you get 1000 deg C from sunlight?

Even the world’s hottest place experiences a maximum temperature of about 57 degrees C!

So, is it possible to achieve a temperature of 1000 degrees C using sunlight?

Sounds impossible? But it can be achieved through the principle of sunlight concentration.

A specialized field called concentrating solar thermal (CST) has existed for quite a while. CST solutions have been able to routinely generate temperatures upwards of 400 degrees C, hot enough to run a steam turbine to generate electricity.

Recently, some startups have used the same technique of sunlight concentration to achieve much higher temperatures. A Swiss startup, Synhelion, claims to produce temperatures of up to 1500 degrees C – a temperature at which the technology can even replace coal in cement clinkers requiring very high temperatures.

Solutions such as those from Synhelion have the potential to decarbonize many high temperature industrial processes that did not have a choice but to use fossil fuels until now.

A Minute for Climate

30% industrial heat applications need less than 100 deg C

Industrial heating worldwide consumes massive amounts of energy, and is a significant source of CO2 emissions.

Interestingly, a sizable portion of industrial heating requires temperatures less than 100 degrees C – studies in the EU have shown that about 30% of all the industrial heating applications required temperatures of 100 deg C or less.

Sub 100 deg C temperatures for industrial heating is an important threshold as this temperature can be realized through the use of solar thermal technologies. The ordinary residential solar water heaters can provide temperatures up to 70 degrees C and the ones customised for specific industrial purposes can provide temperatures up to 100 degrees C.

Such solar thermal technologies are low cost, easy to operate systems with fairly attractive payback periods for many industries.

Given all these, it should come as a big surprise that a large percentage of such industrial and commercial heating applications worldwide are not using solar thermal solutions right now!

A Minute for Climate

10 times solar water heaters as solar panels

When we talk about solar energy, most times we discuss electricity from solar panels.

But solar energy has been contributing to low carbon energy use long before solar panels made their appearance – in the form of solar water heaters.

As of 2023, while there are around 25 million rooftops using solar panels for electricity, there are an estimated 250 million rooftops using solar water heaters worldwide.

Solar water heaters, in other words, are present in ten times the number of houses as solar power systems!

The simple and maintenance free operations of solar water heaters, combined with the fact they can be used in most parts of the world – including in cold regions – have ensured that a large and growing number of households worldwide use solar water heaters as a clean, zero carbon source of domestic water heating.

A Minute for Climate

More power from solar panels – just be cool

Solar panels need to be in the hot sun to be in business.

High sunshine – especially in tropical regions – might mean a lot of electricity generated, but this in most cases also implies that the panels can get quite hot.

Will high temperatures affect the output of the solar panels? They sure will.

Solar panels generate at their highest efficiency at ambient temperatures of 25 degrees C, and for every degree increase in temperature beyond that, their efficiency decreases.

Solar panels operating in a hot desert with ambient temperatures at 50 degrees C could thus operate at a 12-15% lower efficiency – resulting in significant decrease in electricity output.

That’s a lot of electricity lost – especially for large scale solar power plants in such regions which could run to 100s of MWs in a single location.

The obvious solution is to cool these solar panels so that their temperatures reach close to 25 degrees C, and such cooling is being attempted using both air and water.

By the way

Ambient temperatures much lower than 25 degrees C can also result in lower panel efficiencies. These are however relatively less of a concern compared to higher temperatures, as most large solar power plants operate in regions with high temperatures and not low temperatures.

A Minute for Climate

100+ – The brain behind Li-ion batteries is over 100 years old!

Not everyone of you would have heard about John Goodenough, though we feel he deserves to be far more familiar than he is.

Goodenough is one of the key scientists credited with the invention and development of the Li-ion battery.

Goodenough received his bachelor’s degree in mathematics from Yale University in 1943 and his master’s and Ph.D. in physics from the University of Chicago later. He subsequently taught at MIT and Oxford before joining the University of Texas, Austin.

The recipient of a number of prestigious awards, he received the Nobel Prize for Chemistry in 2019 for this work on Li-ion batteries.

Goodenough was born in July 1922. That makes him over a 100 years old as of 2023.

Now, there’s something more astonishing. As of 2021 – aged 98 – he was regularly working in his laboratory, hoping to find the next battery breakthrough.

And as of April 2023, the University still lists him in its list of faculty.


A Minute for Climate

Can we make coal from biomass?

It is generally accepted that most coal that we used today were formed from plant materials.

If that were so, can we make coal from the hundreds of millions of tons of agricultural waste available worldwide?

Yes. It is possible to convert biomass into a material very similar to coal through a process called torrefaction.

Torrefaction refers to the slow heating of biomass in an inert (no air/oxygen) environment in the temperature range of 200–300°C. The resulting material resembles coal in many aspects so much that torrefied biomass is often called green coal.

Torrefaction is different from combustion, a process in which the entire energy present in the biomass is converted into heat and all you have left is ash. In the case of torrefaction, you preserve most of the energy in the biomass while transforming it into a material that could replace coal for power generation and heating applications.

By the way

Not surprisingly, many coal power plants around the world are keenly experimenting the use of torrefied biomass blended with coal to reduce overall CO2 emissions.

A Minute for Climate

Geothermal power plants can help us make batteries

No, we are not kidding.

Geothermal energy is heat energy from the earth’s crust.

Some regions of the world (think Iceland) are blessed with massive geothermal activity right under their surface. Such regions are ideal for setting up geothermal power that can use the hot water from under the earth to run a turbine and generate power.

The interesting thing about the hot geothermal waters is that, these also contain small amounts of many metals, and that includes Lithium. And Lithium is the sought after metal today because it forms the main material in Li-ion batteries that power everything from our electronics to electric vehicles.

This provides the geothermal power plants an excellent opportunity to double up as an important source of raw material for energy storage, in addition to generating clean power!

By the way

The concentration of Lithium in geothermal waters is not very high – about half a gram per liter of brine – but given that Lithium could fetch good prices (US $55/Kg as of Feb 2023) in a fast growing market, and a large geothermal power plant could be processing over a million liters of brine per hour, there is indeed an interesting business case for extracting Lithium from geothermal power plants.

A Minute for Climate

Do biofuels emit CO2?

You might have heard of biofuels – these are typically liquid fuels like ethanol or biodiesel that can partially or fully replace fossil transport fuels such as gasoline or diesel.

World over, many vehicles are encouraged to run on biofuels.

But biofuels are hydrocarbons too. When any hydrocarbon burns, it emits CO2. And so do biofuels, in amounts comparable to those from conventional transport fuels.

So, running a car on biodiesel or ethanol will emit CO2 for sure. But the carbon emitted was originally captured from the atmosphere by a plant from which the biofuel was derived. As a result, you are only emitting back to the atmosphere what was originally captured from it, unlike in the case of gasoline or diesel where, you are emitting carbon to the atmosphere that was originally under the earth.

This is the reason that biofuels are considered to be a low carbon alternative to conventional transport fuels – implying that, there is a significant reduction in emissions when the entire life cycle is accounted for.

By the way

Biofuels are estimated to cut down net CO2 emissions by 75-80% compared to diesel or gasoline based on a life cycle analysis evaluation.

A Minute for Climate

A whale is worth 33 tons of CO2

Whales have massive bodies. And massive bodies store massive amounts of CO2.

An adult whale could weigh a bit more than 100 tons – about the same as the maximum takeoff weight of a Boeing 720. Imagine that.

More importantly for climate, an adult whale could sequester up to 33 tons of CO2 in its body. And when the whale dies and sinks, it carries this massive amount of CO2 along with it to the ocean floor – where the CO2 could stay undisturbed for centuries!

The International Whaling Commission reports there are about 1.5 million whales swimming around in the world’s oceans – with only about 15,000 of them being blue whales, the largest of the whale species.

The CO2 sequestration potential of whales have recently come into the climate action discussion – so much that there are some who are demanding a massive increase in whale population worldwide to combat climate change!

A Minute for Climate

How much CO2 does a tree capture?

Who doesn’t like trees? They give us food, fiber, materials and capture atmospheric CO2 in large amounts.

But how important is the CO2 capture by trees in the context of climate action?

Specifically, how much CO2 does a tree capture over its lifetime?

The answer depends on which tree one is talking about.

Some exceptional trees such as coastal redwood are estimated to capture a massive 250 tons of CO2 over their lifetime. What about other trees?

Over their lifetime:

  • Oak trees capture anywhere between 2-5 tons per tree
  • Banyan trees about 1 ton, and
  • Salt tolerant trees in mangrove forests as low as 0.3 tons.

Broadly, it can be said that the CO2 capture potential for most trees over their lifetime is in the 1-2 tons range.

But this capture is not spread evenly over the lifetime.

Not surprisingly, the amount of CO2 captured is much less when it a small plant, and much larger amounts when the tree is fully grown. This implies that maintaining a plant over its lifetime is far more important than simply planting it, in the context of climate action.

By the way…

  • The world has about 3 trillion trees in total. Assuming an average lifetime capture of 1 ton/tree, that would be 3 trillion tons of CO2 captured over their lifetime. Taking an average lifetime of 100 years per tree, it would imply that about 30 billion tons of CO2 captured by trees worldwide every year – almost the same as the total annual human-made CO2 emissions!

A Minute for Climate

Can electric cars run entirely from solar panels on their roofs?

If electric cars are going to be the future, will it not be great if their batteries can be continuously charged from electricity generated by solar panels placed on their roofs?

So, is it possible to run electric cars entirely from panels on their roofs?

The short answer is: No, unless you use the car for very short distances everyday.

Depending on the country and user segment, a car could travel a range of 50 Kms to 400 Kms a day.

Let’s take the lower value: 50 Kms. To power a mid sized car for 50 Kms would require a battery with a total energy capacity of 8 kWh.

To generate 8 kWh of electricity in a day, you will require at least 2 kW of solar panels in most regions in the world. A kW of solar panels will occupy a minimum of 100 sq ft, so that would be 200 sq ft needed on the roof of a car for it to support the required panel.

The roof of a car is about 20 sq ft (2 sqm).

So, unless you wish to use your car for just about 5 Kms a day – a rather poor utilization, in our opinion – you need electricity apart from the solar panels on the car’s roof.

By the way…

  • Even for the small amount of electricity that solar panels on a car’s roof can produce, the car needs to be in the sun throughout the day, else the output could be much lower!