What it really takes to go green: A story in numbers

Question: Can India shift entirely to sustainable energy? The short answer is yes. The long answer is what you’re here for.

The brilliant British physicist, mathematician and renewable energy advocate David MacKay has an excellent book called Sustainable Energy—Without the Hot Air (from which a significant chunk of the philosophy has been derived). Which is just what India needs right now. But (surprise!) in the run-up to the ongoing general elections, both major national parties’ manifestos have been sorely lacking in terms of a plan for India’s energy policy.

The Congress’s manifesto mentions in passing that it “will formulate a policy on clean energy in existing power plants that use fossil fuels, and promote green energy to enhance the share of solar and wind energy in the total supply of energy”. Meanwhile, the ruling Bharatiya Janata Party’s manifesto aims to “achieve 175 GW of renewable energy capacity and strive to achieve 10% blending of ethanol in petrol”.

Both are inadequate for a country that is estimated to be home to 1 in 6 people on earth by 2030, and is also one of the fastest growing economies of the world.

The case for a fully green grid (renewables plus nuclear) is straightforward. To avoid a global catastrophe, the consensus is that we need to prevent global mean temperatures from rising more than 2 degrees Celsius above pre-industrial levels. We’re already at 08.-0.9 degrees.

To avoid the ‘2C limit’, as it’s often called, is a bleak challenge. One widely accepted study predicts that 60% reduction in global CO2 emissions by 2050—which is a Herculean task if you think about it—will most certainly still result in disaster. What we need is around 85% of emissions cut by 2050.

But coming back to our initial question, yes, we can—in theory—sustain future energy needs completely with clean energy. But the devil lies in the details, and the reality is that getting to 100% sustainability is a ridiculously difficult challenge. The real question is, just how do we deploy our resources to do that.

In that spirit, I’ve embarked on a little exercise to break down the numbers and construct a possible energy ecosystem for India. All calculations and references are provided at the end. I encourage you to check that out and formulate your own energy mix. Without further ado, let’s get started.

Into the rabbit hole

The US. China. India. Top three energy consumers in the world, at least, in aggregate. But once we account for population, things look a little different.

India’s energy consumption then is roughly 20.3 kilowatt hours per day per person. The global average is 61.2 kWh/day/person, while for the US it’s 221.6 kWh/day/person and for China it’s 71.2 kWh/day/person. A kilowatt hour or kWh is what Indian power companies refer to as one “unit” on your power bill. In simple terms, it’s the power spent if you use ten 100 W bulbs for an hour each day. (There’s also a reason we’re using the rather unwieldy kWh/day/person, rather than just megawatts and gigawatts—read the note at the end of the story if you’re interested.)

The state-run think tank Niti Aayog estimates India’s energy consumption to rise to between 1,175 and 1,522 kilotonnes of oil equivalent (about 37-48 kWh/day/person) by 2047. But let’s untether ourselves from reality and assume we want to live like the developed world.

Assuming efficiency gains by adopting more efficient technology, and accounting for the fact that we want to be a manufacturing hub for the world, let’s set our energy consumption target at 80 kWh/day/person.

That’s four times our current consumption per person, but only a little more than where China stands today. It’s also a little less than the UK (88.4 kWh/day/person), which has managed significant reductions in power consumption over the past decade.

So, a reasonable enough target, since we’re talking about a future decades from now. 80 kWh/day/person by 2050 it is.

And since we need to do this entirely using renewable/sustainable energy, there are only a handful of levers at our disposal: Solar (heating/electricity/biofuels), wind (land/offshore), hydro (river/wave/tidal), geothermal and nuclear. Using these, we have to fill up this bar here:

Alright then.

Sunny side up

Good news: India is fortunate to have over 300 clear, sunny days a year. There are two ways to use this bounty.

  1. Rooftop party

Assume we allot 5 sq. m of rooftop space per person that can be used for rooftop solar. Spread across every home, office and government building.

Now, despite major innovation in solar cells, the best photovoltaic or PV panels in production have an average efficiency of 20-25%. If we deploy 5 sq. m of expensive, 25% efficiency PV panels per person, we generate 5 kWh/day/person—6.25% of our target.

  1. Just deserts

We’ve got the Thar Desert on our hands, with a total area of 170,000 sq. km. If we cover half the desert with cheap 10% efficient solar panels, we can generate about 25 kWh/day/person. Not bad.

(For context, though, the largest solar park in India today is the Pavagada Solar Park in Karnataka, which spans 53 sq. km. And we’re talking about constructing a solar park 1,600 times its size.)

Anyway, our hypothetical bar is off to a nice start.

When the wind blows

Here, too, we have two main options: onshore and offshore wind farms.

  1. Terra firma

India is the fourth largest producer of wind energy in the world after China, the US and Germany. But how much could we plausibly generate? A generous estimate of wind speeds over land at 6-7m/s translates to 2-2.2 W/m2.

Realistically, let’s say we use 10% of the windy parts of the country—then, we generate 12 kWh/day/person (15% of our target).

  1. Out at sea

The winds at sea are steadier and stronger than their counterparts on land, with a power density of nearly 3 W/m2. And in total, India has 5,422 km of mainland coastline, and every country’s “exclusive economic zone”, or EEZ, stretches out about 320 km from the shore. And India’s EEZ is a little over 2 million sq. km.

But realistically speaking, it gets harder to maintain wind turbines far out at sea. So we’ll take a humble 80,000 sq. km (about a third of the area within 45 km of the coast) for our wind farms, giving us 4.5 kWh/person/day (5.6% of our target). So that’s 16.5 kWh/day/person from wind. Let’s round it down to 15, and take a look at our bar.

Riverrun anyone?

About 4% of our energy today is derived from hydroelectricity (0.8 kWh/day/person). Estimating future projections for hydroelectricity is tricky, as it involves predicting monsoon patterns and water flow from regions of higher altitude to regions of lower altitude.

But Niti Aayog estimates the installed capacity of hydroelectricity to grow by 2-2.5x by 2047, which will still translate to around 2 kWh/day/person. But let’s assume we can somehow tap into all of India’s estimated potential for hydropower—about 4.5 kWh/day/person.

Then we can add some more from wave energy and tidal power, which use turbines to generate electricity from, well, the movement of waves and the tides. Wave energy can theoretically give us 1.5 kWh/day/person, but the actual mineable energy is much lower. And going by estimates of tidal potential, we can get another 0.167 kWh/day/person from there. Let’s say another 0.5 kWh/day/person from both, bring our hydro total to 5.

The nuclear option

India has around 0.13 million tonnes of known uranium reserves, and the Department of Atomic Energy recently discovered that the upcoming uranium mine in Tumalapalli has close to 0.05-0.15 million tonnes of reserves. Assuming a generous 0.3 million tonnes of uranium that we want to use over 500 years, we can generate 0.67 kWh/person/day.

Experimental “fast breeder” reactors can use the leftover uranium 60 times more efficiently, giving us 4 kWh/day/person), but India’s real hopes lie with something else—thorium.

Thorium is a radioactive element similar to uranium, which is 3-4 times as abundant in the earth’s crust as uranium. Thorium also can be burned in its entirety in simple reactors, as opposed to 1% of uranium. The United States Geological Survey, in 2011, estimated India to have nearly 0.96 million tonnes of thorium reserves. At 40% efficiency, we can produce 5.7 kWh/day/person for 500 years.

But let’s stretch a little further: Nobel laureate Carlo Rubbia has proposed an alternative reactor design for thorium which, combined with India’s copious reserves, can produce about 30 kWh/day/person (37% of our target).

And that’s a wrap!

A plan that adds up?

We have a mix that—again, in theory—will let us abandon fossil fuels decades from now. And along the way, will let India get rid of its dependence on foreign sources of fuels (which account for nearly half of the country’s energy consumption).

So far, I have explicitly avoided discussing costs and time taken to create industries required for the scale in question. And I haven’t taken into account population growth either. Despite ignoring these constraints, hitting the target of 80 kWh/day/person is far from smooth sailing. Check out the map below to get an idea of the scale of the change needed.

Again, I encourage you to play around with the sources (link below) and make your own plans. Set your own targets and see what we can do.

Going completely renewable is not something we can do over a day, or even over a five-year period (i.e. one government’s term). For a nation that gets ~90% of its energy needs from fossil fuels/non-renewable sources, this transition is not going to be easy. But it is one we need to make sooner, at our volition, rather than later.

Experiment with the data here.

Note: The usual way to refer to country-level power generation is “installed capacity” in terms of megawatts or gigawatts. But our focus is entirely on kWh/day/person. That’s because capacity refers to the peak energy output that a power plant is capable of—and 1 GW solar plant, for instance, can generate 1 GW only for a few hours a day. The actual power output is what we really care about, and that’s where our kilowatt hours come in.

What this also means is that the current government’s target of installing 175 GW of renewable energy capacity (solar and wind) by 2022 is not quite as impressive as it sounds. 175 GW roughly translates to 3.17 kWh/day/person, which is ~4% of our 80 kWh/day/person target. (Also, the government is expected to hit only about three-quarters of that 175 GW target.)

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