There is enormous potential to expand bioenergy in Tasmania which would support Tasmania in many ways. Bioenergy is already the largest source of renewable energy in Australia and the world. In Australia more than half the renewable energy comes from bioenergy, more than hydro, solar and wind combined. Bioenergy is also predicted to expand faster than any other form of renewable energy, producing space and industrial heat, dispatchable electricity, cooling, transport, liquid and gaseous fuels, along with bio products along the way.
Many bioenergy technologies are mature, off the shelf, clean efficient, automated and modern as they have seen rapid uptake over several decades around the world. Tasmania could easily quadruple the energy produced from woody residues increasing returns to the sector and imbedding the forestry supply chain among the community. Should this occur far more than the forestry sector will benefit from an expansion of bioenergy?
Bioenergy supports many sectors of the Tasmanian economy and community and has the potential to contribute income to suppliers of feedstocks, which may come from forestry, agriculture, industrial, and domestic waste streams increasing returns to these sectors, or reduce waste disposal costs.
Bioenergy provides a waste management solutions, it consumes waste that is often left in the landscape to decompose or that adds pressure on the State’s waste management infrastructure.
Bioenergy is carbon neutral under international agreements as the feedstocks are regrown, and when bioenergy displaces fossil fuels, we can reduce our greenhouse gas emissions. As a renewable energy source, bioenergy increases our renewable energy production, and is among the few options available to provide renewable industrial heat. Other renewable energy sources struggle to produce intense or flash heat that bioenergy can produce, hence bioenergy is most competitive against fossil fuel heat production.
Furthermore, bioenergy is often the cheapest way to produce heat, often cheaper than electricity or fossil fuels. Bioenergy supports the local communities by keeping energy expenses in the local community and through employment along the feedstock collection and handling supply chains. Tasmania has huge quantities of feedstocks and enormous potential to realise all these benefits and export additional renewable energy as bioenergy. Many of the potential feedstocks have been quantified and mapped by the Australian Biomass to Bioenergy Assessment Project found here: https://nationalmap.gov.au/renewables/.
Bioenergy is most suited to producing industrial scale heat (for industrial processes or space/water heating for larger buildings) from organic residues generated close to the bioenergy facility. If an entity can consume energy generated from its own residues, low energy costs and waste disposal savings can make bioenergy very cost effective. It is possible for several entities to both purchase energy from a bioenergy facility and provide feedstocks, forming a bioenergy hub and circular economy. This can smooth feedstock supply curves and energy off demand curves and achieve economies of scale. Bioenergy can be used as an attractor for heat intensive businesses where large quantities of feedstock are available. Most of Tasmania’s industrial precincts can be supplied with large quantities of feedstock.
A larger bioenergy facility can become a waste/residue accumulation centre that allows for bio-refining or processing of waste to produce higher value products. Without the aggregation for bioenergy many products potentially suited to biorefining would be uneconomic to collect. In this way bioenergy is often a first and a necessary step toward a circular economy. Since bioenergy facilities have the potential to accept a wide range of feedstocks, as one feedstock is redirected to higher processes, other feedstocks can replace this and potentially support other bioprocessing opportunities. In this way a centre for bio refining and more sophisticated circular economy can be supported by bioenergy.
Bioenergy is usefully divided into combustion and anaerobic digestion. Combustion is suited to dry waste (<60-65% moisture content) and anaerobic digestion is suited to wet waste. Combustion produces heat in a boiler, anaerobic digestion produces biogas (predominantly methane) that can be burned in a boiler to produce heat, or in a reticulating engine that generates electricity to drive an industrial process.
Bioenergy can produce reliable, high intensity heat. Setting up a bioenergy heat plant is more cost-effective than making electricity, and consequently bioenergy is most competitive with fossil fuel (coal, LNG, LPG, natural gas, diesel) driven industrial heat process and not electricity generation.
Steam from boilers can be passed through a turbine to generate electricity. Bioenergy just for electricity is not seen in Australia as the additional equipment costs for power generation are generally too high to allow the electricity to be sold into the grid at a competitive price. A bioenergy to electricity plant is more expensive than a bioenergy to heat plant (often double or more the price). Further, approximately 3.7 units of heat are needed to make 1 unit of electricity making electricity production relatively inefficient compared to heat production.
However, some boilers set up for industrial heating may have excess heat at times that is not needed for industrial processes. This excess heat can be used to generate electricity, increasing the overall energy recovery from the bioenergy plant. Further, heat from boilers/reticulating engines can be used in absorption chillers to provide cooling. Hence bioenergy facilities can produce combinations of heat, electricity and cooling.
It is more cost effective to produce electricity “behind the meter” to existing customers in close proximity than to sell it into the grid, or to circulate heat up to 500m from the bioenergy plant (in some cases much further if costs can be justified), and to circulate biogas at low pressure behind the meter. Reticulating biogas at low pressure behind the meter is straightforward from a technical standpoint but it needs to be tested through regulation in Australia.
The capital spent on biomass boilers is recovered more quickly when they are used on a continuous basis. Furthermore, when cooling down and heating up the boiler goes through thermal cycling that, if done frequently, can shorten the boiler life. Hence boilers become less economic if not used 24/7. For smaller operations, such as heating glasshouses with reticulated hot water, a boiler may be attached to a buffer tank containing water heated by the boiler when direct process heat is not required.
For larger boilers this is not possible because the buffer tank would need to be uneconomically large. In some cases (such as sugar mills) the boiler can be used to make electricity that is sold to the grid, at around cost recovery, to enable the boiler to economically produce heat and dispose of a waste fuel. The quantity of electricity that can be expected to be sold into the grid by bioenergy plants under the above circumstance is minor and will not compete with hydro, solar PV or windfarms for scale. However, under some circumstances it may be more cost-effective to produce electricity regionally, for example, where grid connections are problematic.
Anaerobic digestion (AD) produces biogas that can be stored in vessels for use when required. This provides flexibility for application to businesses that do not operate 24/7 where a boiler or reticulating engine can be powered by biogas. The costs of distributing biogas at low pressures in pipes to users behind the meter is not a significant cost. This may displace fossil fuels directly, such as natural gas. Producing behind the meter electricity also may become viable when using AD as the AD plant can be sized to produce the energy needs of the business while operating 24/7 and wet wastes are often associated with high trade waste charges or other disposal costs. Often the avoided trade waste charges are the most important economic factor.
A combination of combustion and anaerobic digestion allows an industrial precinct to deal with all organic waste forms generated or available in the vicinity. Furthermore, woody feedstocks can smooth out seasonal fluctuations in other feedstocks and provide scale to bioenergy facilities. The desirable combustion characteristics of wood waste can allow less attractive feedstocks that otherwise could not be fired alone, to be co-fired with wood, increasing the potential feedstocks available for bioenergy. Hence the forestry sector is likely to be a primary beneficiary of the expansion of bioenergy and should be a strong supporter of the sector which is likely to receive federal support soon through the development of a bioenergy roadmap that we can prepare for https://arena.gov.au/news/arena-to-develop-roadmap-to-boost-bioenergy-opportunities-in-australia/
Martin Moroni is the Manager Business Development of Private Forests Tasmania