ZCA 2020
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What is Beyond Zero Emissions?
Zero Carbon Australia 2020 (ZCA) is an exciting initiative of Beyond Zero Emissions and the University of Melbourne's Energy Research Institute.
It is a project to develop a blueprint for the transition to a decarbonised Australian economy by 2020, drawing on the enormous wealth of knowledge, experience and expertise in the community to develop a blueprint for transitioning Australia to a zero carbon future. Individuals with expertise, knowledge and experience in relevant areas can work within a structured process to contribute to the transition plan.
Zero Carbon Australia 2020 (ZCA) is an exciting initiative of Beyond Zero Emissions and the University of Melbourne's Energy Research Institute.
It is a project to develop a blueprint for the transition to a decarbonised Australian economy by 2020, drawing on the enormous wealth of knowledge, experience and expertise in the community to develop a blueprint for transitioning Australia to a zero carbon future. Individuals with expertise, knowledge and experience in relevant areas can work within a structured process to contribute to the transition plan.
ZCA 2020 and the NT.
ZCA 2020 Stationary Energy Plan.
Part 3 : Australia’s 100% renewable energy supply
3.4.2 Biomass — Co-firing with CST plants
It is recommended that biomass be used to fire CST plants when the solar resource is inadequate for consecutive days over several solar sites. This co-firing method has the benefit of eliminating the need to install more turbines, as combusting biomass can heat the molten salt — which would otherwise be heated by the sun — to make steam to drive the solar plant turbines. The only extra capital cost incurred would be a biomass-fired burner, a simple and mature technology. It is also a more economical option to heat the salt, which operates near atmospheric pressure, than directly boiling steam in the biomass heater, which operates at much higher pressure and therefore requires more expensive materials. The winter shortfall in power delivered by CST could also be addressed by increasing the CST capacity under the plan. However, using other forms of renewable energy generation adds resilience to the system and reduces the overall cost. It is proposed that enough biomass heater capacity be installed to supply 15 GWe of the CST plants with backup.
Biomass from woody weeds – a better option for the Territory.
It has been estimated by NT Government Weeds Branch that mimosa pigra covers approximately 100,000 ha. in the NT. When this weed reaches 90% monoculture it produces from 35 -45 ‘wet’ tonnes per ha. If harvested efficiently (using a biobaler), it is reasonable to expect that more than 1 million wet tonnes p.a using rotational harvesting. This figure could be doubled if other weeds (including gamba, mission grass and parkensonia) and savanna forests were also harvested to reduce bushfire fuel loads. Within 10 years it would be possible to produce in the order of 3 – 5 million tonnes p.a. by rotational harvesting of purpose grown bioenergy crops on mine remediated sites and plantations such as the 30,000 ha acacia mangium on Tiwi islands.
Transport of bulk biomass — biomass pellets for greater energy density
Biomass is usually of a lower energy density than fossil fuels, so is traditionally seen as better suited to a distributed energy system, with small-scale, local energy generation reducing the need to transport bulky biomass long distances. In recent times, a technology known as ‘pelletisation’ has become widespread in North America and Europe. Woody biomass (e.g. woodchips and/or crop waste) is pressed and extruded into pellets or briquettes, which have a higher energy density and lower moisture content, making transport and storage more economical. The product is commonly referred to as ‘wood pellets’, but crop wastes are regularly used to manufacture them as well as wood waste. Wood pellets are used for domestic, commercial and industrial purposes in North America and Europe. The 2005 global wood pellet market demand was estimated to be 30 million tonnes. In contrast, the 92 PJ/annum CST backup only requires 5.3 million tonnes of biomass pellets. These would be transported by rail to the solar sites. The transport of pellets by rail is a small task by comparison with exports of coal at the port of Newcastle, the world’s largest coal export terminal, which is currently running at 92.8 Mt/annum, and is expected to expand to 133 Mt/annum by 2011.
Small scale pelletisation plants, which are commonly used in Europe and North America, can be set up in areas where there is significant woody weed/energy crop resource. The pellets will be transported through the existing and upgraded rail system to the CST plants, where it can be stored in bunkers until required. 2,500 tonne trains, each consisting of 100 x 25 tonne wagons, would be used in the late summer / early autumn to transport pellets from the pelletisation plants to the bunkers at the CST plant sites. The trains would then be placed on standby locally at the CST plants over the critical winter period, where there may be a need for biomass co-firing in order to continue seamless operation of the electricity supply system. The electricity requirements for this transport will be small compared to the rest of transport activity in the economy, but it should also be noted that this haulage task will be taking place over the summer/autumn period where there will be excess energy availability from wind and solar.
The pelletisation of the 5.3 million tonnes of waste in 5 months during the dry season, would require 150 small scale pelletisation plants with a capacity of 10 tonnes/hr, operating 24 hours a day during the period. These would be set up in remote communities, and could be either allocated to a single site (e.g. a growth town) or share input from several smaller communities. Cost. From industry sources, a 10 tonne/hr pelletisation plant would cost $AU8.3million.
The total cost for 150 crop waste pelletisation plants would be $AU 1.25 billion.
Part 3 : Australia’s 100% renewable energy supply
3.4.2 Biomass — Co-firing with CST plants
It is recommended that biomass be used to fire CST plants when the solar resource is inadequate for consecutive days over several solar sites. This co-firing method has the benefit of eliminating the need to install more turbines, as combusting biomass can heat the molten salt — which would otherwise be heated by the sun — to make steam to drive the solar plant turbines. The only extra capital cost incurred would be a biomass-fired burner, a simple and mature technology. It is also a more economical option to heat the salt, which operates near atmospheric pressure, than directly boiling steam in the biomass heater, which operates at much higher pressure and therefore requires more expensive materials. The winter shortfall in power delivered by CST could also be addressed by increasing the CST capacity under the plan. However, using other forms of renewable energy generation adds resilience to the system and reduces the overall cost. It is proposed that enough biomass heater capacity be installed to supply 15 GWe of the CST plants with backup.
Biomass from woody weeds – a better option for the Territory.
It has been estimated by NT Government Weeds Branch that mimosa pigra covers approximately 100,000 ha. in the NT. When this weed reaches 90% monoculture it produces from 35 -45 ‘wet’ tonnes per ha. If harvested efficiently (using a biobaler), it is reasonable to expect that more than 1 million wet tonnes p.a using rotational harvesting. This figure could be doubled if other weeds (including gamba, mission grass and parkensonia) and savanna forests were also harvested to reduce bushfire fuel loads. Within 10 years it would be possible to produce in the order of 3 – 5 million tonnes p.a. by rotational harvesting of purpose grown bioenergy crops on mine remediated sites and plantations such as the 30,000 ha acacia mangium on Tiwi islands.
Transport of bulk biomass — biomass pellets for greater energy density
Biomass is usually of a lower energy density than fossil fuels, so is traditionally seen as better suited to a distributed energy system, with small-scale, local energy generation reducing the need to transport bulky biomass long distances. In recent times, a technology known as ‘pelletisation’ has become widespread in North America and Europe. Woody biomass (e.g. woodchips and/or crop waste) is pressed and extruded into pellets or briquettes, which have a higher energy density and lower moisture content, making transport and storage more economical. The product is commonly referred to as ‘wood pellets’, but crop wastes are regularly used to manufacture them as well as wood waste. Wood pellets are used for domestic, commercial and industrial purposes in North America and Europe. The 2005 global wood pellet market demand was estimated to be 30 million tonnes. In contrast, the 92 PJ/annum CST backup only requires 5.3 million tonnes of biomass pellets. These would be transported by rail to the solar sites. The transport of pellets by rail is a small task by comparison with exports of coal at the port of Newcastle, the world’s largest coal export terminal, which is currently running at 92.8 Mt/annum, and is expected to expand to 133 Mt/annum by 2011.
Small scale pelletisation plants, which are commonly used in Europe and North America, can be set up in areas where there is significant woody weed/energy crop resource. The pellets will be transported through the existing and upgraded rail system to the CST plants, where it can be stored in bunkers until required. 2,500 tonne trains, each consisting of 100 x 25 tonne wagons, would be used in the late summer / early autumn to transport pellets from the pelletisation plants to the bunkers at the CST plant sites. The trains would then be placed on standby locally at the CST plants over the critical winter period, where there may be a need for biomass co-firing in order to continue seamless operation of the electricity supply system. The electricity requirements for this transport will be small compared to the rest of transport activity in the economy, but it should also be noted that this haulage task will be taking place over the summer/autumn period where there will be excess energy availability from wind and solar.
The pelletisation of the 5.3 million tonnes of waste in 5 months during the dry season, would require 150 small scale pelletisation plants with a capacity of 10 tonnes/hr, operating 24 hours a day during the period. These would be set up in remote communities, and could be either allocated to a single site (e.g. a growth town) or share input from several smaller communities. Cost. From industry sources, a 10 tonne/hr pelletisation plant would cost $AU8.3million.
The total cost for 150 crop waste pelletisation plants would be $AU 1.25 billion.
Primary energy
sources: past, present and future.
( from Thermodynamic analysis of biomass gasification and torrefaction. Mark Jan Prins (2005) http://alexandria.tue.nl/extra2/200510705.pdf (accessed 8/3/11)
( from Thermodynamic analysis of biomass gasification and torrefaction. Mark Jan Prins (2005) http://alexandria.tue.nl/extra2/200510705.pdf (accessed 8/3/11)