Global Climate News: July 8-9

Hottest June on record, Hydrogen-powered combustion engines, Denmark's certification for e-fuels, Renewable natural gas from food waste

In this newsletter

• Hottest June on record

• Hydrogen-powered combustion engines

• Top stories

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Hottest June on record

It was the hottest June on record for the globe and the 13th month in a row to set a monthly temperature record. While unusual, a similar streak of monthly global temperature records happened previously in 2015/2016.

According to Copernicus Climate Change Service ERA5 data, the month was 1.50°C above the estimated June average for 1850-1900, the designated pre-industrial reference period. This is the 12th consecutive month to reach or break the 1.5°C threshold.

The global-average temperature for the past 12 month period (July 2023 – June 2024) is 1.64°C above the 1850-1900 pre-industrial average, according to the ERA5 dataset.

World Meteorological Organisation | UN News

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Hydrogen-fuelled Combustion Engines

Vehicles powered by hydrogen are no longer confined to the lab. Hydrogen is being used to run trucks and buses at the Wiri logistics hub in New Zealand, Forklift trucks at Amazon’s fulfilment center in Colorado (USA), and Hytrolleys in Latvia. The recently held 24 Hours of Le Mans also held a competition of hydrogen-powered race car prototypes over a 13km track.

Here’s an overview of how the hydrogen-powered engine works, challenges in using it - mainly around NOx emissions, and current research areas.

How the hydrogen-powered engine works

Hydrogen is taken into the combustion chamber and mixed with air.

This mixture is then compressed by the piston, increasing its temperature and pressure. At the top of the compression stroke, a spark ignites the hydrogen-air mixture, leading to a rapid combustion process that generates high-pressure gases. This pressure pushes the piston down, converting the chemical energy into mechanical energy. The heat released from the combustion expands the gases, resulting in a power stroke that propels the engine.

(Here’s a marvellous blog by Bartosz Ciechanowski on the workings of internal combustion engines, with fun visuals)

Because hydrogen is lighter and has a simple molecular structure, its flame travels faster (270 cm/s) compared to diesel (22-25 cm/s) and gasoline (30-50 cm/s), making it a more efficient fuel. This allows it to burn faster and deliver more performance.

However, common combustion engine problems like backfiring and knocking also occur with hydrogen-powered engines.

• Backfiring is when the fuel (prematurely) ignites during the fuel intake into the combustion chamber, likely due to high temperature

• Knocking is when fuel-air mixture in the combustion chamber spontaneously combusts before the spark plug fires. Diesel and gasoline with a high octane number reduce knocking. Hydrogen has a high research octane number (RON), but is prone to knocking

Handling NOx emissions

Using hydrogen as fuel eliminates CO2 emissions from combustion, but there are nitrogen oxide (NOx) emissions. These arise mostly from reactions between atmospheric nitrogen and oxygen at high temperature, unless the fuel also contains hydrocarbons or nitrogen compounds (like ammonia in it). Formation of NOx increases exponentially with temperature, becoming a major concern at temperatures above 2200K. A few strategies to address NOx emissions are being tried:

• Exhaust gas recirculation

  It works by routing a portion of the exhaust gases back into the engine's intake manifold, where they are mixed with the incoming air-fuel mixture. This means less oxygen reaches the cylinder, and less oxygen implies a lower combustion temperature leading to a reduction in significant reduction in NOx emissions.

  EGR reduces the internal temperature of the engine by upto 20%, which reduces NOx emissions, and can also reduce backfiring and knocking.

• Water injection - adding a small amount of water to the fuel-air mixture

• Lean combustion - uses less fuel and more air when injecting fuel into the engine. This reduces NOx emissions, but also reduces power output

• Adding inert gases

• Tweaking engine parameters - injection timing, compression ratio, swirl and injection timing

• Selective Catalytic Reduction systems - used in diesel and petrol vehicles as well; use a mixture of urea and water, which is sprayed into the engine exhaust to convert nitrogen oxides to ammonia; may be leading to elevated urban ammonia levels

Current research areas for hydrogen use in engines

• Blending with methane, natural gas, biogas, biodiesel, ammonia, methanol

• Blending hydrogen with CNG, called HCNG, improves combustion efficiency and lowers emissions. 20-30% hydrogen blending is suggested

• Storing hydrogen - solid-state hydrogen storage materials, advanced tanks for cryogenic storage of liquid hydrogen; materials like metal hydrides, carbon-based substances, metal-organic frameworks (MOFs), and nanomaterials for storing hydrogen

• Upgrading existing pipelines for transporting hydrogen - steel embrittlement, degradation of seals, compressor station reinforcements,

Race towards net-zero emissions by 2050: Reviewing a decade of research on hydrogen-fuelled internal combustion engines (PDF)

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Top Stories

1. Denmark has approved a certification scheme for Power-to-X (PtX) producers to certify hydrogen produced from renewable energy as ‘green’. While EU has approved regulations that set requirements regarding how synthetic fuels should be produced, the EU-wide certification scheme has not been finalised yet. Denmark has pre-approved the scheme in collaboration with the relevant EU body to allow producers in the country to begin production, and will allow them to transition to the EU-wide certification once approved.

   the Danish Energy Agency has chosen to pre-authorize certification of PtX fuels under the ISCC EU certification scheme. This means that Danish PtX manufacturers and customers can already begin the process of being certified. This ensures regulatory security for those PtX manufacturers who expect to start production soon.

   The Danish Energy Agency's prior approval is valid until the European Commission's approval is available. This is expected to happen this year, which is why the Danish pre-authorization will be a short-term transition solution. Thereafter, the certification will at all times follow the rules approved by the European Commission. (Translated from Press Release)

   pv magazine | Press Release (in Danish)

2. In June, EU approved €131 million funding for the Northern Lights project - a joint initiative between Equinor, Shell and Total to receive liquefied CO₂ from capture facilities at the Northern Lights Terminal and store it in a reservoir in the Norwegian Continental Shelf. Northern Lights Project | ET Energy

3. US-based Synthica Energy produces renewable natural gas by anaerobic digestion of organic waste. Their facilities can accept liquid waste (like a batch of spoilt beer), solid waste (such as from food processing facilities), damaged agricultural produce, as well as packaged food waste (beverage cans and frozen food unfit for consumption) as feedstock in the digesters. The facility in St Bernard (Ohio, USA), will be able to process 190,000 tons of organic waste when complete and is located such that the gas produced can be fed into the existing natural gas pipeline network. businesswire | Synthica Energy

4. Spain’s Acciona has launched a light, short-range (149km) electric vehicle with removable batteries that can be charged at home or swapped for fully recharged batteries at 120 stations across the country. The company is selling the vehicles without the battery, and allowing buyers to use the batteries on a subscription model. Acciona Press Release | ET Energy

5. Good read on using satellites for methane detection from Waste Dive

You can find all previous posts of this newsletter here.

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