Bio-waste into Fertilisers

Currently over 90% of the urea produced utilises natural gas as the feedstock. The company said that its use of common agricultural waste products and other natural biomass, not chemicals or natural gas in its process is a significant step forward.

Demand

In 2009, the International Fertiliser Association (IFA) estimated that North American consumption was 14.3 million tonnes (13 million tonnes) annually. In the US alone, in 2009, the IFA estimated that urea consumption was at 11.44 million tonnes (10.3 million tonnes), while production came to just 6.4 million tonnes (5.8 million tonnes). The IFA has stated that with increasing demand and unchanged capacity, urea imports by the United States are likely to grow to around 7.7 million tonnes (7 million tonnes) per year.

According to the IFA, every year the world consumes 170 million tonnes of fertiliser for food, feed, fibre and fuel – where 48% of the world’s food is produced with the use of nitrogen fertiliser. Without the use of fertiliser, two billion more people would be threatened by hunger. According to a 2010 study conducted by the IFA the global market for urea will grow at 3.8% per year from 2009 to approximately 192.5 million tonnes (174.6 million tonnes) in 2014 – the bulk of this increase is expected to come from growing demand for urea fertiliser.

The IFA also forecast that industrial applications for urea, accounting for 12% of total consumption, will grow by 7% per year between 2009 and 2014. The company also cites a further IFA study conducted in May 2011 which predicted that demand for urea will increase 10.7% from 168.6 million tonnes (153 million tonnes) to 188.8 million tonnes (171.3 million tonnes) in 2014.

To help meet this demand, the company said that its model is focused on building small-scale, fully operational plants on a turnkey basis. Each production facility is estimated to manufacture 15 tonnes (13.6 tonnes) of urea fertiliser per hour for a total annual production of approximately 124,200 tonnes (112,700 tonnes) per plant.

The Process

BioNitrogen concept is to gasify biomass, which is a carbon-based mixture of organic molecules containing hydrogen, usually oxygen, often nitrogen and also small quantities of other atoms, including alkali, alkaline earth and heavy metals. The resulting gas is converted into urea. The feedstock for the process is primarily agricultural residual products such as sugar cane bagasse, palm fronds, trunks, rice and peanut hulls, cotton byproducts and corn stover. The biomass is dried, cleaned and ground to a consistent size and gasified.

The resultant syngas then passes through a series of cleaning steps to remove any elements that could be detrimental to the downstream processing. The clean syngas is then passed through a series of catalytic reaction stages for transformation into the desired end product. During this stage of processing, specific chemicals are separated out and recycled to the appropriate points in the process.

As a result of the recycling, the company claimed that there is no requirement for byproduct vent streams. Therefore, up to 100% of the feed carbon content can be converted to syngas and/or the final product, urea.

The by-products created by its process are electricity, which is used to help run the plants with the excess sold to the grid as a secondary revenue stream, fly ash, which can be sold to cement manufacturers as a secondary revenue stream, and water, which is reused in the process in a closed loop system.

Furthermore, the company has claimed that because the method recycles the harmful greenhouse gases that are separated out during the gasifying and reforming processes, its urea production system has virtually no negative impact on the environment, and qualifies for carbon credits.

Waste Management World