Low Global Warming Potential Polycarbonate.

HighLine is pleased to launch a new Low Global Warming Potential Polycarbonate extruded sheet. The aim of this blog post is to explain a little about what this means.

Global Warming Potential (GWP)

One measure of the environmental impact of a product is the Global Warming Potential (GWP). GWP is measured as Kg of CO2 equivalent / kg of product and is a measure of the Global warming impact of a product in terms of the equivalent amount of CO2 released to the environment.

Most Polycarbonate sheet on the market has a GWP of 5.5 kg CO2 per kg of sheet. That means that the environmental impact of each Kg of sheet is the same as releasing 5.5kg CO2 to the atmosphere.

For a sheet producer, there are a number of ways to reduce the GWP of the polycarbonate sheet. To reduce the impact, it is first important to understand what factors go into the GWP value. The following list breaks down the main factors:

• The base polycarbonate resin is about 4.2 kg of CO2 per kg of product
• Energy to produce the sheet is about 0.9 kg of CO2 per kg of product
• Transportation of the sheet to the customer is about 0.2 kg CO2 per kg of product
• Other factors such as labor and travel add about 0.2 kg CO2 per kg of product

The total of these factors is about 5.5 kg CO2 per kg of product.

Energy

One of the easiest ways to reduce the GWP is to reduce the impact of the energy. Energy reduction can be achieved by using a modern production line with energy efficient drives. HighLine does this by using the latest production equipment to produce the material. However, the process used to make sheet still requires a significant amount of energy as the material must be heated up to melt the polycarbonate resin and then cooled down to make sheet.

The other way to reduce the energy component of the GWP is to use green energy. HighLine’s product is made using all energy generated using Hydroelectric power. This energy has a GWP of 0.01 kg CO2 per kWh, compared to most energy sources used for sheet that have a GWP of 0.5 kg CO2 per kWh. Using Hydroelectric power reduces almost 0.9 kg CO2 per kg of product off the GWP of our polycarbonate sheet.

Transport

HighLine also has arrangements with Green shippers to reduce the emissions associated by shipping. We also use rail which is more efficient. As the impact of shipping is only around 0.2 kg CO2 per kg product, we will not discuss it further here, other than saying we are making transport decisions using environmental impact as a factor.

Regrind and PCR resin

The main impact on the GWP of polycarbonate sheet is the polycarbonate resin itself. The resin used by virtually all manufacturers has a GWP of 4.2 kg CO2 per kg of product. I hear many producers trying to “Green wash” their product saying that they are using “regrind”. It is important to understand what they mean by “regrind” and how it impacts the GWP.

Types of regrind

• The first type of regrind is material generated internally at the factory. It consists of edge trim cut off the sheet to give a smooth edge finish and off specification sheet. This material is ground up and reintroduced to the extruder. Virtually all producers reuse this type of regrind and could reuse many times more if they had it. It is built into the GWP figures for the sheet. If a supplier offers you a material with a high level of this type of regrind, it just means that they are putting none into the sheet of another customer. Overall, there is no Net benefit to the environment. The manufacturers should not be claiming to be green by using internally produced regrind; they are just doing it to control costs.
• Post industrial regrind is next type of regrind that manufactures are using. When material is shipped to a distributor or large customer, they often fabricate the material and off-cuts are generated. These off-cuts are returned to the manufacturer and are re-used to make sheet. There are some difficulties of this process, including controlling contamination. The claim is often made that using post industrial regrind prevents material ending up in land fill, the reality is often different. Most post industrial regrind was previously sold to scrap dealers, who ground and compounded the pellets for use in less critical applications. So in reality, post industrial regrind doesn’t lower the GWP of the sheet products.
• Post consumer regrind is where the real opportunity for environmental impact is found. Previously, material such as polycarbonate in old car headlights could not be re-used. This was because the material was contaminated, often coated with a hard coat and had suffered environmental degradation of the properties. This meant that a significant quantity of material, at the end of the products life, was going to landfill. HighLine has worked with a major polycarbonate producer to capture this Post Consumer Regrind (PCR) and reuse it to make sheets. These sheets are exceptionally high quality with no loss of optical or physical properties. In addition the GWP of the PCR resin is 1.76 Kg CO2 per kg of resin compared to 4.2 kg CO2 per kg Resin for standard polycarbonate.

Cost of PCR resin

Internally produced regrind and post industrial regrind are often used for the sheet manufacturer to save cost. It is an added advantage that they can “claim to be green”. In contrast, Post Consumer Regrind, while being a good environmental solution, does have significant costs. There are cost associated with collecting, sorting, cleaning, reprocessing and compounding the material. In fact, the process is so complicated it has taken over ten years to develop material to the state where it can be used to produce optically clear Low Global Warming Potential Polycarbonate sheet.

As far as we know, HighLine is the only sheet producer in the world to have produced extruded clear polycarbonate sheets from PCR material made from car headlights.

The downside of the PCR resin is that it does add a little to the cost of the sheet. We are expecting to offer the sheet at around a 20% price premium for sheet containing 20% PCR.

GWP of 20% PCR sheet.

HighLine is now testing Low Global Warming Potential Polycarbonate extruded sheet at customers with 20% PCR and 80% standard Polycarbonate resin. This gives an average GWP of the resin of (20% x 1.76) + (80% x 4.2) = 3.7 kg CO2 per kg of resin. A reduction of 0.5 kg CO2 per kg of resin.

Coupled with using hydroelectric power and green transport we have achieved a reduction in the GWP of the sheet from 5.5 kg CO2 per kg of product to 4.0 kg CO2 per kg product; a 27% reduction in emissions. At the moment we are going through third party audited verification to bak up our internal calculations.

On the positive side, we have successfully test produced sheet with up to 50% PCR, so if customers want an even lower GWP product it is available. We expect to test at even higher concentrations in the near future.

Low Global Warming Potential Polycarbonate sheet available for testing.

We now have a limited stock of sheet containing 20% PCR resin with a GWP of about 4.0 kg CO2 per kg product. Please note that the third party verification will be completed later this year to verify the figures. Although we do have a fully verified Life Cycle Assessment for the PCR resin showing it has a GWP of 1.76 kg CO2 per kg of product.

The current stock is 1/8″ x 4′ x 8′ sheet.

We also have the capability to take orders to produce more material with PCR resin. As this is a new product there are extended lead times for the next six months as we evaluate how much PCR resin we need to order. After that, we expect the material to be a stock item.

Please contact us at info@highlinepc.com or call us on 267.847.0056 to discuss this exciting new Low Global Warming Potential Polycarbonate sheet product.