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There are a number of Renewable Energy areas where Process Projects can provide solutions by working closely with specific technology providers beginning at the feasibility study stage all the way through to EPCM.
These are:
• Steam Rankine cycle
Gasification
Gasification is the partial combustion of fuel to convert a solid or liquid fuel into a gaseous fuel containing hydrogen, CO and CO2. This fuel can be used to power engines or gas turbines to drive generators or can be used to produce liquid fuels via Fischer Tropsch or other similar catalystic processes. Companies such as Coskata (www.coskata.com) and Ineos (www.ineos.com) have produced microbes that are able to convert this gas directly to ethanol.
Gasification and use of the syngas is typically more energy efficient than combustion.
Fuels that can be used depend on the type of gasification system under consideration. Downdraft gasification is particularly sensitive to fuel shape while updraft has the problem of unburnt tars that need to be removed if the gas is to be used in an engine. Appropriate fuels include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, sorted municipal waste, sewerage sludge, etc. Fuels with high concentrations of alkali are more challenging technically though there are systems that can deal with them.
Plasma Gasification is redefining gasification technology.
Pyrolysis
Pyrolysis is the conversion of a solid fuel in the absence of oxygen to a mixture of gas, liquid and solid components. Fast pyrolysis maximizes the conversion to liquid oil while slow pyrolysis produces more gas and char.
Pyrolysis should be considered as a concentration step able to convert a low energy density fuel to a high energy density fuel that can easily be transported. Unfortunately, pyrolysis oil is acidic and generally unsuitable for direct use though some specialized equipment has been developed for this role (www.dynamotive.com).
The benefit of pyrolysis is that plants can be positioned to minimize fuel transport costs as the fuel is generally low density eg chicken litter, sawdust or corn cobs. The oil from the distributed plants can be transported to a central facility where the oil can be gasified to produce a syngas suitable for conversion to power, heat or to liquid fuels via FT or other similar technologies. Dynamotive for example have produced high grade fuel from pyrolysis oil.
Fuels that can be used include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, chicken litter, etc. Fuels such as shredded tyres and other industrial wastes with calorific value can also be pyrolised.
Organic waste containing volatile fatty acids (VFA) can be digested to convert the VFA to biogas. Biogas typically contains 2/3 methane and 1/3 CO2 by volume with hydrogen sulphide (H2S) dependent on the sulphur content in the feed waste.
After scrubbing out the H2S, biogas can be used as an excellent fuel. It can also be scrubbed to remove CO2 before being compressed and stored as a synthetic natural gas. In this form it can be used to fuel vehicles such as buses and other public transport. It can also be used in any application where natural gas is used.
Concentrating Solar Thermal
There are a number of renewable energy technologies that can be offered in this area. The most common process is based on parabolic reflectors that rotate to follow the course of the sun. While initially this technology was only used for large-scale electriciy production, the latest technology using smaller more compact parabolic trough technology allows anything from 250 kW to 20 MW.
An alternate renewable energy process is the compact linear Fresnel lens (CLFR). Here (simpler to produce) flat mirrors are used to reflect the sun onto a stationary collector. These systems are significantly simpler than parabolic systems and are less vulnerable to wind damage. However, they are not able to harvest the early morning and late afternoon sun as well as the parabolic reflectors requiring them to be bigger to produce the same output.
There are a number of Renewable Energy areas where Process Projects can provide solutions by working closely with specific technology providers beginning at the feasibility study stage all the way through to EPCM.
These are:
• Steam Rankine cycle
• Plastic to oil
• Waste to oil
• Anaerobic digestion
• Concentrating solar thermal
Steam Rankine Cycle
This is the classic combustion route where hot gas is used to produce steam which is used to drive a steam turbine which drives a generator to produce power. Process steam can be extracted from the turbine if required and condensed for process heat.
Renewable Energy Fuels that can be used include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, chicken litter, etc. Fuels such as shredded tyres and other industrial wastes with calorific value can be burnt in more sophisticated combustors.
• Concentrating solar thermal
Steam Rankine Cycle
This is the classic combustion route where hot gas is used to produce steam which is used to drive a steam turbine which drives a generator to produce power. Process steam can be extracted from the turbine if required and condensed for process heat.
Renewable Energy Fuels that can be used include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, chicken litter, etc. Fuels such as shredded tyres and other industrial wastes with calorific value can be burnt in more sophisticated combustors.
Organic Rankine Cycle
Instead of boiling water to produce steam, the organic Rankine cycle uses an organic fluid that boils at a lower temperature than water. As a result, what is considered low grade waste heat can be used to generate power. As a result, there are systems that can use hot water at 93ºC as the heat source. While these systems only have about 15% efficiency due to the low temperature, this energy is recovered from a waste source.
The size of these units begin at 2kW and go up to MW range. 60kW and 120kW units come as pre-packaged units.
Gasification
Gasification is the partial combustion of fuel to convert a solid or liquid fuel into a gaseous fuel containing hydrogen, CO and CO2. This fuel can be used to power engines or gas turbines to drive generators or can be used to produce liquid fuels via Fischer Tropsch or other similar catalystic processes. Companies such as Coskata (www.coskata.com) and Ineos (www.ineos.com) have produced microbes that are able to convert this gas directly to ethanol.
Gasification and use of the syngas is typically more energy efficient than combustion.
Fuels that can be used depend on the type of gasification system under consideration. Downdraft gasification is particularly sensitive to fuel shape while updraft has the problem of unburnt tars that need to be removed if the gas is to be used in an engine. Appropriate fuels include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, sorted municipal waste, sewerage sludge, etc. Fuels with high concentrations of alkali are more challenging technically though there are systems that can deal with them.
Plasma Gasification is redefining gasification technology.
Pyrolysis
Pyrolysis is the conversion of a solid fuel in the absence of oxygen to a mixture of gas, liquid and solid components. Fast pyrolysis maximizes the conversion to liquid oil while slow pyrolysis produces more gas and char.
Pyrolysis should be considered as a concentration step able to convert a low energy density fuel to a high energy density fuel that can easily be transported. Unfortunately, pyrolysis oil is acidic and generally unsuitable for direct use though some specialized equipment has been developed for this role (www.dynamotive.com).
The benefit of pyrolysis is that plants can be positioned to minimize fuel transport costs as the fuel is generally low density eg chicken litter, sawdust or corn cobs. The oil from the distributed plants can be transported to a central facility where the oil can be gasified to produce a syngas suitable for conversion to power, heat or to liquid fuels via FT or other similar technologies. Dynamotive for example have produced high grade fuel from pyrolysis oil.
Fuels that can be used include wood, wood waste, agricultural waste such as corn cobs and stalks, nut shell, chicken litter, etc. Fuels such as shredded tyres and other industrial wastes with calorific value can also be pyrolised.
Torrefaction
This is a process whereby wood based products are dried and devolatalised by heating it up to about 300°C. The smoke and gas given off is generally burnt to provide heat to the torrefaction reactor. Supplementary fuel may be required with high moisture wood.
Plastic to Oil
There are at least two companies that have developed thermal depolymerisation plants to produce diesel equivalent oils from waste plastic such as PET, LDPE, HDPE, etc.
Waste to Oil
There are at least two companies that have developed proprietary catalytic depolymerisation plants to produce diesel equivalent oil from waste materials such as tyres, plastic, sawdust, cattle manure, sewerage sludge, agricultural waste, sorted municipal solid waste, etc.
Anaerobic digestion
Organic waste containing volatile fatty acids (VFA) can be digested to convert the VFA to biogas. Biogas typically contains 2/3 methane and 1/3 CO2 by volume with hydrogen sulphide (H2S) dependent on the sulphur content in the feed waste.
After scrubbing out the H2S, biogas can be used as an excellent fuel. It can also be scrubbed to remove CO2 before being compressed and stored as a synthetic natural gas. In this form it can be used to fuel vehicles such as buses and other public transport. It can also be used in any application where natural gas is used.
Concentrating Solar Thermal
There are a number of renewable energy technologies that can be offered in this area. The most common process is based on parabolic reflectors that rotate to follow the course of the sun. While initially this technology was only used for large-scale electriciy production, the latest technology using smaller more compact parabolic trough technology allows anything from 250 kW to 20 MW.
An alternate renewable energy process is the compact linear Fresnel lens (CLFR). Here (simpler to produce) flat mirrors are used to reflect the sun onto a stationary collector. These systems are significantly simpler than parabolic systems and are less vulnerable to wind damage. However, they are not able to harvest the early morning and late afternoon sun as well as the parabolic reflectors requiring them to be bigger to produce the same output.
In both cases, oil or water is heated up. The oil can be used directly or stored and later used to generate high pressure steam (or organic vapour) to drive a steam (or organic) Rankine cycle. Hot water from the collectors can be flashed down to produce low pressure process steam.
The final technology is the central tower. Here multiple heliostats mounted in an array around a central tower reflect sunlight to a single point. Molten salt is sometimes used to absorb the heat. Hot molten salt can be stored and used in the hours of darkness allowing solar to extend its production envelope to include the night time hours. A new technology has been developed by eSolar (www.esolar.com) with multiple towers simplifying the heliostat field.
The final technology is the central tower. Here multiple heliostats mounted in an array around a central tower reflect sunlight to a single point. Molten salt is sometimes used to absorb the heat. Hot molten salt can be stored and used in the hours of darkness allowing solar to extend its production envelope to include the night time hours. A new technology has been developed by eSolar (www.esolar.com) with multiple towers simplifying the heliostat field.