This is a series of briefs on the most widely adopted renewable energy technologies. This brief deals with bio-ethylene production, and touches on the economic policy implications and provides insights on Canada’s status in bio-ethylene production. The information is adapted from the International Renewable Energy Agency (IRENA) Technology Briefs for the year 2013.

The Science

A simplified overview of the steps involved in bio-ethylene production is given in Figure 1 below.

Ethylene is a petrochemical used for the production of important synthetic polymers, including high- and low-density polyethylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate.

The first step in bio-ethylene production is the creation of bio-ethanol from biomass feedstock. This is a well-known process as bio-ethanol is now used as a transportation fuel. Three types of biomass can be used: sucrose (e.g. sugarcane, sugar beets), starchy feedstock (e.g. wheat, corn, barley), and lignocellulosic feedstock (e.g. wood, straw, grasses).

Once bio-ethanol has been produced and purified to chemical grade, it is converted to bio-ethylene by an alumina or silica-alumina catalyst. One tonne of bio-ethylene requires 1.74 tonnes of hydrated bio-ethanol.

 

Figure 1 - Process Flow Diagram

(Sourced from http://chematur.se/process-areas/bio-chemicals/bio-ethylene-ethene/)

 

The Economics

When compared to petrochemical production, sugarcane-based bio-ethylene can save about 19 GJ of non-renewable energy (60%) per tonne of output, and emit about 0.7t of CO2eq (40% less). Results show that bio-ethylene from corn starch and ligno-cellulose can save respectively 40% and 100% of non-renewable energy compared to petrochemical ethylene.

Production cost estimates of bio-ethylene from starchy and sucrose feedstock in Brazil and India sit around USD 1,200/t; relatively cheap compared to estimates in other countries. The production in the U.S. and the EU are estimated to be at USD 2,000/t and USD 2,500/t, respectively. Bio-ethanol production from ligno-cellulosic biomass via biochemical processes was estimated to cost about USD 750/t in 2012, assuming mature technical and economic conditions. This leads to a bio-ethylene production cost of around USD 1,900/t and is slightly cheaper than the current thermochemical production routes at about USD 2,000/t.

Bio-ethylene production is typically more expensive than petrochemical ethylene, and producers may be hesitant to invest in this novel production route. To overcome these barriers, producers may set a premium price of about 15-30% on their bio-polyethylene products compared to petrochemical polyethylene.

 

Policy Making Implication

The implementation of bio-ethylene depends on the amount of bio-ethanol available, and various barriers currently exist to the wide use of bio-ethylene.

The current production of bio-ethylene from sugarcane in Brazil, however, provides a good platform to build on, where production of sucrose or starchy feedstock is large enough to supply bio-ethanol for large-scale bio-ethylene production. The conversion of food plantations to bio-ethanol production, on the other hand, can increase food prices with a dramatic impact on developing countries. One way to address this challenge is through biochemical or thermochemical conversion of ligno-cellulosic biomass into ethanol, which, if it can be made cheap and competitive, can enlarge the basic feedstock availability with minor or no impact on food production.

Ethanol import duties also hinder scaling-up production bio-ethylene. The EU, for example, levies an import tariff on ethanol of up to USD 310/t.

 

Canadian Insight

In Canada, ethylene is the primary petrochemical product made in the largest quantity from whichever feedstock is used. Ethylene is produced in Alberta, Ontario, and Quebec and used at nearby plants to make derivatives including ethylene oxide, ethylene glycol, ethylene dichloride, vinyl chloride monomer, and polymerized to synthetic resins including polyethylene, polyvinyl chloride, polystyrene, and synthetic rubber.

Most of the recent growth in the Canadian industry has occurred in Alberta, based almost exclusively on natural gas feedstocks. However, there are bio-resources available to make ethanol in Alberta, including wheat and cellulosic sources, and, additional ethylene availability should be welcomed in the province as derivative production could expand, as suggested by a study conducted in 2014. One of the key challenges to bio-ethylene made via ethanol from wheat in Alberta would be, expectedly, to produce it at a low cost and provide it at a price to derivative producers (customers) that would allow them to be competitive in global markets. Competing with ethane-based ethylene is expected to be a challenge. A potential advantage for derivative producers in using bio-ethylene is that it would allow them to differentiate their product offering in the marketplace. There might be a price premium available for certain bio-polyethylene grades derived from renewable sources in a sustainable manner, but the willingness of consumers to pay such premiums remains questionable.

The Biochemicals Initiative within the Government of Alberta aims to facilitate linkages between consumer-facing brands with an interest in bio-chemicals and traditional petrochemical manufacturers of Alberta seeking engagement and investment in growing the biochemical industry in Alberta.

A NOVA Chemicals ethylene manufacturing complex in Joffre, Alberta
A NOVA Chemicals ethylene manufacturing complex in Joffre, Alberta

(Sourced from: http://www.novachem.com/Pages/company/joffre-alberta.aspx)

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