More types of fuel


The decay of much biomass produces methane, or ‘natural gas’. The idea is that it is possible to capture or generate methane from waste, and rather than release it to the atmosphere, burn it to produce energy and presumably some GHG. The point here is not that no GHG is released, but it is used as it is released.

China has more than 100,000 biogas plants, and a large number of household biogas units, followed by Germany with over 10,000 plants.

Methanol is another form of biogas made from biomass at extremely high temperatures and in the presence of a catalyst


It is also possible that plastics could be converted to biofuels  – exchanging one form of pollution for another less noticeable form. Australian energy startup Licella was funded by Renewable Chemical Technologies Ltd (RCTL) and Armstrong Energy (£5m) to convert plastics to oil suitable to blend in with hydrocarbon fuels. It can work with broken and mixed plastics, and paper. However, the production of plastics locks away carbon, while conversion and burning releases it, so you get rid of the plastic from landfill or oceans but put it in the air, – along with any other pollutants. This is the case even if the production process is lower in emissions than usual. Given plastics are usually made from fossil fuels, fuel made from plastic should probably be classified as processed fossil fuels.


Waste or rubbish is one of the more confusing categories. It can include biogas but also high temperature burning of rubbish such as plastics and other materials which might be otherwise put into landfill. It may add to transport emissions if trucks carry the waste from the landfill area to the incinerator. The heat is usually used to produce steam and drive turbines to produce electricity. (A commercial description can be found here). It is dubious that burning mixed materials will have low emissions, or low particulate pollution, and the ash left behind is likely contaminated with heavy metals, salts, and persistent organic pollutants. Modern incinerators also have air pollution control equipment, which adds to the energy and cost of operation. The US EPA claims:

A typical waste to energy plant generates about 550 kilowatt hours (kWh) of energy per ton of waste. At an average price of four cents per kWh, revenues per ton of solid waste are often 20 to 30 dollars… [another] stream of revenue for the facilities comes from the sale of both ferrous (iron) and non-ferrous scrap metal collected from the post-combusted ash stream.

The United States combusted over 34 million tons of Municipal Solid Waste [MSW] with energy recovery in 2017…

 The ash that remains from the MSW combustion process is sent to landfills. 

EPA Energy Recovery from the Combustion of Municipal Solid Waste (MSW)

A medical survey of evidence concluded that:

A range of adverse health effects were identified, including significant associations with some neoplasia, congenital anomalies, infant deaths and miscarriage, but not for other diseases. Ingestion was the dominant exposure pathway for the public.

More recent incinerators have fewer reported ill effects, perhaps because of inadequate time for adverse effects to emerge. A precautionary approach is required.

Peter W Tait et al. 2020. The health impacts of waste incineration: a systematic review. Aust N Z J Public Health 44(1):40-48.

Another article on the same topic claimed:

We found a dearth of health studies related to the impacts of exposure to WtE emissions. The limited evidence suggests that well-designed and operated WtE facilities using sorted feedstock (RDF) are critical to reduce potential adverse health (cancer and non-cancer) impacts, due to lower hazardous combustion-related emissions, compared to landfill or unsorted incineration. Poorly fed WtE facilities may emit concentrated toxins with serious potential health risks, such as dioxins/furans and heavy metals; these toxins may remain problematic in bottom ash as a combustion by-product. 

Tom Cole-Hunter 2020 The health impacts of waste-to-energy emissions: a systematic review of the literature. Environmental Research Letters,15: 123006

Not unreasonably they call for further research before expanding the industry.

In the US, The Department of Energy announced:

$46 million for 22 projects that will create biofuel energy to help decarbonize the transportation and power generation sectors.

Turning waste and carbon pollution into clean energy at scale would be a double win—cleaning up waste streams that disproportionately burden low-income communities and turning it into essential energy,” said U.S. Secretary of Energy Jennifer M. Granholm.

Unusually, they try to sell the waste burning, as removing waste streams from low-income communities, and lowering pollution, both of which seem dubious.

In Australia, the government has also seen incineration ‘renewable energy’ and as creating revenue streams for industry, and then allowing industry to apply for grant programs, through people such as the renewable energy agency Arena and the Clean Energy Finance Corporation. Promotion of rubbish for energy also came about shortly after China refused to take more Australian rubbish exports, and this allows recycling centres to sell on otherwise unwanted recycling materials.

Burning rubbish would seem to be a way of not having to lower rubbish-pollution, increase recycling, or find new ways of recycling. In other words it allows freeloading polluters to continue to freeload and rubbish-collectors to make extra profits. It may even encourage more plastic manufacture. to provide feedstock.

Sustainable Aviation fuel

Aviation fuel is a major cause of GHG. By 2019, the total annual world-wide passenger count was 4.56 billion people.

passenger air travel was producing the highest and fastest growth of individual emissions before the pandemic, despite a significant improvement in efficiency of aircraft and flight operations over the last 60 years…

if global commercial aviation had been a country in the 2019 national GHG emissions standings, the industry would rank number six in the world between Japan and Germany.

Jeff Overton 2022 Issue Brief | The Growth in Greenhouse Gas Emissions from Commercial Aviation. Environmental and Energy Study Institute 9 June

In 2017 the aviation industry promised carbon neutral growth by 2020.  The “green jet fuel” plan, promised and increase use of biofuels to 5m tonnes a year by 2025, and 285m tonnes by 2050, which is about half the overall demand, assuming it remains stable, and stops growing. This is also about three times the amount of biofuels currently produced, and that suggests that the blowback would be considerable. Nearly 100 environmental groups protested against the proposal. Klaus Schenk of Rainforest Rescue said: “The vast use of palm oil for aviation biofuels would destroy the world’s rainforests” and Biofuel watch estimate it would take an amount of land more than three times the size of the UK.

British Airways abandoned a £340m scheme to make jet fuel from rubbish in January 2016, while Qantas managed a 15 hour flight from the US to Australia using a fuel with a 10% blend of a mustard seed fallow crop. The flight reportedly reduced the normal emissions of the flight by 7% which suggests a long way to go. At the time it was reported that Qantas aimed to set up an Australian biorefinery in the near future in partnership with Canadian company Agrisoma Biosciences. I do not know if this has happened, but they claimed that in Jan 2022 they became the first Australian airline to purchase Sustainable Aviation fuel out of Heathrow in London. It “will represent up to 15 per cent of our annual fuel purchased out of London…. and reduce carbon emissions by around 10 per cent on this route.” The fuel was said to be produced with certified bio feedstock from used cooking oil and/or other waste products. This is then blended with normal jet fuel. Qantas Group Chief Sustainability Officer Andrew Parker said “Aviation biofuels typically deliver around an 80 per cent reduction of greenhouse gas emissions on a lifecycle basis”. This seems unlikely while it is blended with jet fuel, and does not really compare with the 7 to 10 percent reduction they were previously claiming.

Reuters states that “Only around 33 million gallons of SAF were produced last year globally, or 0.5% of the jet fuel pool”. Stuff from the Biden bill