Thread by @knowb4its2l8

Thread

A news headline from @ShippingWatch yesterday says the energy needed to fuel the 8 new @Maersk methanol newbuildings with green methanol (360,000 tons per year) would be more than Denmark's RE output.

1/12

I can't find the exact number for Denmark's RE output, but let's assume it's around 80 TWh per year. Let's also assume that the energy use of the entire deep sea fleet of global shipping is 1,000x the consumption of these 8 newbuildings.

2/12

So if the news headline is correct, that would mean that international shipping needs at least 80,000 TWh of carbon free energy to synthetically build enough fuel to carbon-neutrally power the world's merchant fleet.

3/12

A typical nuclear reactor produces 1 gigawatt (GW) of electricity, or ~8 TWh per year. So, we would need about 10,000 typical nuclear power plants to produce all the truly green methanol needed to power all the large ships in the world.

4/12

A good rule of thumb is that it takes 5 acres per MW peak for a solar farm. Note that includes spacing, roads, inverters, everything. Actual farms vary from about 4 acres to 9 acres per MW.

Thus 5,000 acres would be a good guess at the area needed for a 1GW solar farm.

5/12

So we would need 50,000,000 acres, or about 200,000 square kilometres of solar farm for a similar output. Very roughly an area of 450 x 450 kilometres completely covered in solar panels and infrastructure. And it would probably have to be renewed every 25 years.

6/12

Wind farms with the same output would take even more space. @NEI says wind farms require 360 times more land area to produce the same amount of electricity and solar photovoltaic plants require 75 times more space than does nuclear power plants.

7/12

So a wind farm of about 1,000,000 square kilometres, or roughly 1,000 x 1,000 kilometres is needed to fuel the world's merchant fleet in a carbon neutral manner. And wind turbines also need replacement every 25 years or so.

8/12

Nuclear power generation of 80,000 TWh could be done on an area of about 2,500 square kilometres, or 50 x 50 km. And nuclear can easily achieve a life span of 50-75 years, double/triple that of solar & wind.

Wind 1,000 x 1,000 km
Solar 450 x 450 km
Nuclear 50 x 50 km

Now think of the carbon foot print of building out these sized areas with wind, solar and nuclear and remember that for wind & solar you will have to do it 2-3 times as often as the nuclear reactors.

10/12

And think of the fact that shipping is <3% of all global emissions, so you can appreciate the scale required for green energy to neutralise all CO₂ emissions.

11/12

My point here is simply to illustrate the scale of the challenge we are facing and to make you think about these numbers.

It's obvious that solar & wind can play a part but I can't see a world where we meet the challenge without #nuclearpower.

12/12

.@threadreaderapp unroll

To follow up on this thread, there was another article in @ShippingWatch yesterday, about how much energy is needed to “build” synthetic, renewable ammonia (syn-fuel) in order to propel ships.

The problem is two-fold:

Secondly, to “build” syn-fuels, you need much more energy input than what you actually store in the syn-fuels. The efficiency of converting energy harvested by wind or solar (or any other method) into energy stored in e.g. ammonia is rather low.

For these reasons (not to mention challenges with the storage and transportation of fuels like H2, NH3 or CH3OH, compared to that of oil) it will take a huge amount of energy to replace the 350 million tons of oil that shipping consumes each year with synthetic, green fuels.

This is echoes the Twitter musing I wrote last year (above). I was, however, off by a factor of almost 10, because it really doesn’t take “more green power than is currently available on an annual basis in Denmark” to produce ammonia for 8 large container ships.

Using updated numbers, to replace 350 million tons of oil, we need 750 million tons of ammonia. To produce this amount of ammonia using electrolysis of water for the hydrogen, and combining it with nitrogen taken from the air, requires ~9,000,000,000 MWh (=9,000 TWh) of energy.

The annual amount of power produced by the worlds ~440 nuclear power plants each year is about 2,500 TWh, so it would take something like 1,600 nuclear power plants to produce enough ammonia for shipping alone to be able to convert to zero-carbon fuels.

Coincidentally, the amount of energy produced by wind and solar worldwide each year is a bit above 2,500 TWh, which is a further illustration of how much solar and wind (~3-4x today) we would need to produce all the fuel used by shipping, in green form instead of fossil.

Not insurmountable challenges, but the scale is indeed worth noting. And, of course, the logic of using small, nuclear reactors onboard ships instead.

Ups, forgot the first of the two-fold problem:

Firstly, the energy density of syn-fuels, like hydrogen, methanol, or ammonia, is much less than of oil. You therefore need more syn-fuels than you do oil, for the same amount of work.