New Zealand's biomass resources
Once upon a time, we used to call the byproducts of primary industry rubbish – like pulp from juice factories, prunings from grape vines or slash (harvest residues) from forestry. Now these waste streams are seen as valuable resources and are grouped with other biomass streams – they’re called residue biomass. Biomass streams offer exciting opportunities to convert renewable resources and what was once considered waste into useful new materials or fuel alternatives.
The drive to convert biomass is part of a global drive to find solutions to a number of wicked problems such as:
climate change caused by the burning of non-renewable fossil fuels for transport and to power industry among other things
single use plastics and plastic pollution caused by many plastic types being non-biodegradable.
What is biomass?
Biomass is anything that has a biological origin. Common biomass sources are plants such as wood, corn and maize. If something has an organic origin, it has energy embodied in it that has the potential to be extracted and be used as an energy source.
Points of interest
Effluent is wastewater and sewage from towns, cities or businesses (such as what you find left over in the cow shed!).
What is biomass?
We use the term ‘biomass’ to describe living or recently dead biological material. Biomass contains stored energy produced from the Sun. Plants absorb the Sun’s energy through a process called photosynthesis. When we burn biomass, for example, wood in an oven, the chemical potential energy that was stored is transformed into heat energy.
Residual waste and biomass
Peter Hall from Scion explains that residual biomass is material created as a byproduct from making something else.
Residual biomass is a term that is used to describe waste products from biomass resources that can be used to produce energy. Wood off-cuts left behind in the forest are a good example of this. However, energy demands outnumber what can be supplied by using residual biomass. In order to supply a growing demand of renewable energy resources, residual biomass could be supplemented through purpose-grown products.
Burning wood is not the only way to release energy, and wood is not the only type of biomass available. Typically, the term biomass is used to refer to plant material but it can also include animal matter or biodegradable wastes. Organic material that has been transformed through geological processes, as is the case for fossil fuels, is not included in this description.
Different biomass streams also present different chemical structures and components that can be utilised in the drive for biodegradable and compostable materials and bioplastics that can replace more problematic plastic types, such as those that cannot be recycled.
Net clips from grape skins
Scion Science Leader Biopolymers & Chemicals Dr Florian Graichen talks about a novel new product made for the wine industry from its own waste streams.
New Zealand has a strong primary industry focus. This means that we also have many biomass streams available. In New Zealand, the biomass resources can include woody resources (including leafy plants), agricultural plant resources, residue from agriculture and forestry, as well as municipal (civic waste from towns and cities) and industrial wastes (this includes liquid sewage and manure).
Biomass and forestry
Peter Hall from Scion talks about the biomass streams produced by the forestry industry.
Forestry waste is produced at nearly all stages of wood processing. For example, the trunk might break leaving a top that is too thin to be used as a log when a tree is felled, branches must be trimmed off creating smaller unusable wood residue, the bark may be removed during processing at the sawmill or sawdust may be produced when the logs are further processed.
New materials from biomass
In New Zealand, there is a lot of research looking at ways to utilise biomass from waste streams. The results of some of this research are already in production, such as the Zespri biospife – a compostable tool for eating kiwifruit made from kiwifruit residues – created by Scion and Zespri. Another product developed by Scion is the grape vine net clip – made from marc – the left over grape skins and seeds from the juicing process.
Potatopak (now rebranded as Earthpac) makes and sells potato plates. The biodegradable plates are made from potato starch – a waste product from chip-making.
Bark biorefinery project and PHAs
Chief Innovation and Science Officer Dr Elspeth MacRae and Science Leader Biopolymers & Chemicals Dr Florian Graichen explain their work at Scion on a “fascinating” group of polymers called polyhydroxyalkanoates (PHAs).
Biofuels
Biofuels are fuels that can be produced from or made up of a renewable material. Biomass streams that could be utilised for biofuel production are municipal solid waste (rubbish that often goes to landfills), waste wood from construction and demolition, harvest residues left in forests and co-products from existing biomass processing such as chips from sawmills or tallow from meat processing.
Biofuels can be part of a suite of solutions to reduce the current dependence of New Zealand on fossil fuels for transportation. The use of fossil fuels for transport is a significant percentage of New Zealand’s greenhouse gas emissions that are contributing to climate change. Road transport made up 43% of New Zealand’s carbon dioxide emissions in 2018 – emissions from this source increased by 22% between 2009 and 2018.
Aotearoa’s contributions to greenhouse gas emissions
Drew Bingham from the Ministry for the Environment discusses two approaches for looking at greenhouse gas emissions: production and consumption.
Notes: When Drew talks about energy, he is referring to the energy we use to create goods or fuel our vehicles – for example, electricity and fossil fuels. This differs from the energy that humans add to the atmosphere via greenhouse gas emissions.
Drew also talks about GDP, which stands for gross domestic product. GDP is the total value of goods and services produced in a country during a specific time period, normally a year. GDP is used as an economic indicator to show the economic health of a country.
Questions for discussion:
What is the most common way of reporting New Zealand’s emissions?
Who do you think should be responsible for greenhouse gas emissions – the country that makes the goods or the people who use them? Why?
Why do you think that New Zealand’s carbon dioxide emissions are increasing even though technology is creating more fuel-efficient vehicles?
Right now, liquid biofuel use in New Zealand is less than 0.1% of total liquid fuel sales. Fonterra’s Anchor Ethanol plant is producing bioethanol from whey – a byproduct of cheese. This is blended with petrol and sold at retail outlets. There is also work being carried out to produce biodiesel from tallow (animal fats) and other biomass streams.
Some of the biggest hurdles for the development and use of biofuels here is the high cost of setting up to produce the biofuel and other value-chain issues. Growing a crop specifically for biofuel may also result in land being taken away from food production – something New Zealanders may not support.
Food versus fuel
Peter Hall from Scion talks about using land to grow crops for food or fuel.
If we are growing mass resources like maize or canola, these crops are taking away land that would normally be used to grow food crops, increasing the pressure on food prices. To avoid this problem, biomass resources should ideally be grown in places that are unsuitable for food crops. In New Zealand, this could mean looking at the high country, or steep gullies.
The use of biomass from waste streams has a number additional hurdles including:
available volumes of biomass are low compared to fuel demand
tallow and sawmill chips already have existing end uses and established values outside of biofuel use
it might not be technically or economically feasible to collect biomass that may be dispersed throughout the country.
There are a number of technologies that are used to convert energy from biomass material into fuel we can use. Not all of the technologies available have been used to produce biofuel or tested to run at a commercial level in New Zealand.
Conversion technologies for biofuels
Conversion technologies
Peter Hall from Scion discusses different combustion technologies that can turn biomass into useable forms of energy, like heat or liquid fuel.
There are different ways of converting biomass into energy, depending on the resource and what the energy is used for. For example, combustion is the burning of a fuel source such as wood – a process that is being used by many New Zealand households as well as by industry that requires direct heat. A more complex process is when resources like wood are converted into either gas or a liquid fuel. Peter Hall also describes the process of pyrolysis, which describes the extraction of a liquid from biomass producing bio oil, a liquid fuel.
Here are examples of conversion technologies and how useful they might be to generate fuel from biomass:
Combustion – the burning of biomass to generate heat (for example, wood). The energy product generated is either heat or heat and electricity. Combustion technology is used to heat water. The resulting steam can drive an electricity generator, and the heat that is produced can still be used. This technology is commonly used in New Zealand.
Gasification – using partial combustion to produce gas from biomass. Usually, the types of gases that are being produced are carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H) and methane (CH4), which can then be used in internal combustion engines. This technology is not yet fully commercial in New Zealand.
Pyrolysis – using heat in the absence of oxygen to break down organic matter to its chemical components. The energy product using this technology is typically bio-oil. To produce a bio-oil, moderate temperatures are needed. The original biomass material needs to be dry for this process. There are no commercial pyrolysis systems in New Zealand working on fuel, but there are a number of commercial operations and enthusiasts around the country using pyrolysis to make biochar – carbon specifically burnt to add to soil – in order to reverse climate change through carbon sequestration and provide valuable soil conditioners. A number of these groups are members of the Biochar Network New Zealand. A news video and further information can be found here.
Anaerobic digestion – naturally degrading organic material in the absence of oxygen that produces biogas. This technology is typically used to treat wastewater sludge and organic waste. Anaerobic treatment has been applied to a wide variety of solid and liquid organic wastes, including waste from food and beverage production (sugar, soft drink, potato, vegetable, distillery and brewery wastes); meat, dairy and wool processing; and pharmaceutical and chemical industries. The significant advantages of anaerobic processes are low energy use and reduced sludge production, generation of biogas and the ability to extract valuable fertilisers from the digested residue. This technology is well established in New Zealand.
Anaerobic digestion
Peter Hall from Scion explains how anaerobic digestion is a technique used to convert liquid effluents and wastes into a gas.
Anaerobic digestion is a process that converts wet or liquid wastes (such as sewage) into a gas (for example, methane). Liquid waste (effluent) is stored in ponds, and anaerobic bacteria are introduced to these ponds. The microorganisms break down the waste in the absence of oxygen, and in this process, they produce methane, which we can capture and use to generate heat or electricity.
Points of interest: Why is anaerobic digestion good for the environment? (Tip: greenhouse gases)
Chemical and mechanical processing – converting canola, waste oil and tallow from meat processing to biodiesel by pressing and or transesterification. This technology is used in New Zealand to produce biodiesel in relatively small quantities from waste cooking oil. It is most likely that canola crops may be used for the production of oil for biodiesel.
Biochemical and enzyme technology – this technology involves biological catalysts that can be used at critical stages of the bioconversion process to replace more energy-intensive methods. Ethanol is being produced from biochemical conversions of sugars and starch, for example. The ethanol is usually blended with the petroleum fuels, but they can also be used on their own. Using bioethanol or biodiesel means we don't burn quite as much fossil fuel. Bioethanol and biodiesel are usually more expensive than the fossil fuels that they replace, but they are also cleaner burning fuels, producing fewer air pollutants. This technology is still being researched in New Zealand.
Related content
To understand the drive for new materials to replace problematic plastics, read Rethinking plastics in Aotearoa New Zealand – the report and learn about different plastic types and recycling here.
Get the statistics on Aotearoa’s contributions to climate emissions.
Useful links
For an understanding of the current state of biofuels and issues around producing and using biofuel in New Zealand, take a look at the report NZ Biofuels Roadmap by Scion.
New Zealand's Bioenergy Association has more information on biofuels.
Gen Less is a government agency dedicated to mobilising New Zealanders to be world leaders in clean and clever energy use, explore how business can run more sustainably with renewable energy.
