Plasma gasification: Harnessing the power of lightning

- By:

Courtesy of

Plasma gasification is both a high-tech solution to the problem of waste management and a source of renewable power. The technology has great potential, but can it move from the fringes to the mainstream?

The name 'plasma gasification' conjures up images of men in lab coats late at night, investigating a far-flung corner of science that is light years away from commercial readiness. In reality it is a technology at the forefront of ultra-clean waste management and a means of generating baseload renewable electricity. It may be new and effective, but is it practical?

All plasma gasification techniques use an electric current, an inert carrying gas and powerful electrodes to create 'plasma' — an ionised gas sometimes called the fourth state of matter. Plasma fields occur naturally as lightning.

In plasma gasification, fuel or waste is fed to a reactor vessel where it comes into contact with electrically generated plasma and is heated to temperatures of up to 6,000 degrees Celsius, hotter than the surface of the sun. It is not hard to imagine that when waste, or anything else for that matter, is heated to such temperatures it breaks down into very basic forms — elemental gas and solid waste.

Organic molecules are converted into a syngas that can be used to generate electricity and liquid fuels, while most metals melt or are vaporised and other inorganic solids are converted into glass-like substances that can be marketed to the construction industry as aggregate for use in blocks, brick and gravel.

Plasma gasification is a means of producing clean, carbon-neutral electricity but its other, perhaps more important function, is as a waste management technology. It dramatically reduces the volume of waste, and renders inert harmful substances such as medical or contaminated waste. And unlike most other waste treatment processes, plasma gasification does not produce harmful emissions. As the waste is not burnt, no oxygen is required and the gasifiers can be made airtight.

Terry Moore, CEO and president of Plasma Waste Recycling, a Huntsville, Alabama-based start-up, says it is not just about the environment benefits, it is also commercially interesting: 'Everything that comes out of the process is a product, which means you have a diverse revenue stream,' he explains.

There are two main types of plasma gasification technology: plasma torch systems and graphite arc systems. A plasma torch resembles a large welding torch and consists of two tubular metal electrodes. Once the plasma is ignited with a high voltage current, it is fired from the end of the downstream electrode in a 'plume,' annihilating anything in its path.

Graphite arc systems originated in the steel industry and usually have either one electrode torch in a chamber which contains the return electrode in its lining, or two torches of opposite polarity. French company Europlasma was one of the first to use plasma gasification to process waste and generate power. The venture was founded in 1992 by former engineers at another French firm, Aerospatial, who had been developing plasma torch technology for the purpose of simulating the extreme temperatures experienced by spacecraft and ballistic engines re-entering the earth's atmosphere. In 2001 the company floated on Paris Marché Libre, and CFO Cédric Bérard says it is eyeing a transfer to Alternext Paris in September.

Europlasma aims to become a turnkey provider of standalone plants that generate power from municipal solid waste and industrial and commercial waste. 'You can break the process into three phases,' Bérard explains. 'First you convert waste to fuel, secondly this fuel is converted into a syngas and, finally, the syngas is used to generate electricity, with additional heat recovery. We aim to deliver stages one and two, up to the production of a clean, rich syngas.'

Bérard claims that the overall efficiency of Europlasma's technique is up to double that of existing substitute technologies, yet there are others in the industry making similar claims.

Rod Vera, vice chairman of research and technology at Plasma Waste Recycling (PWR), says graphite arc systems have several advantages over Europlasma's offering. 'The graphite arc plasma process has three major advantages over plasma torch technique,' he argues. 'First, plasma torches need to be water-cooled which means that 28-32% of the energy input is lost to the cooling water. Secondly, plasma arc designs have far greater scalability. Plasma torches are limited to a maximum of 1.5MW to 2MW per torch, whereas there are already examples in the steel industry of graphite arc systems with capacities of 140MW to 150MW. Thirdly,' he finishes, 'the up-front capital cost is far less. Torch designs can typically cost in the region of $2m to $3m per MW whereas graphite arc designs cost around one tenth of that, in the region of $0.2 to $0.3m per MW.'

Moore adds that the graphite arc system does not require the feedstock to be pre-treated. 'Our feeding system does not require shredding or bailing of waste before it can be fed into the chamber. The waste can be used as it comes, straight off the truck,' he says .Like Europlasma, PWR wants to design and build turnkey plants, but not own and operate the facilities once commissioned. Moore says the company, which has partnered with US-based engineering and construction firm CH2M Hill and South African high-capacity furnace maker Tenova Pyromet, will produce10-tonne and 20-tonne per hour systems that can be added in a modular fashion to increase the scale of the plant.

Simon Merriweather, the newly appointed CEO at UK-based Advanced Plasma Power, a firm also developing graphite arc systems, takes issue with the 'no pre-treatment' model. APP is pickier about what it feeds into the plant, which may be more costly but it lowers the overall energy required.

The recyclable elements, oversized objects and grit and glass are removed, he says. The waste is then dried using heat taken from the overall process and fed into a fluidised bed gasifier where it is heated to around 850 degrees centigrade. Only at this point is the 'impure' syngas fed into the plasma converter. 'The advantage of our process is that by vaporising the waste before putting it into the plasma converter we minimise the power requirements of running the plasma converter, and therefore have lower running costs,' he says.

Despite these claims there are concerns that such plants are too energy-intensive. APP calculates that about 40% of the power produced from the waste would be required to operate the plant.

It is this cost and the up-front capital cost that is making investors pause for thought. Paris Moayedi, the former boss of Jarvis, the support services group, that bought APP's parent company in 2004, said in a newspaper interview recently that it would cost GBP 72m to build a plant that processes 150,000 tonnes of rubbish each year, producing 17MW of electricity. This is at the top end of some waste-to-energy cost scales.

However, plasma gasification, like standard gasification and many other waste-to-energy technologies,stands to receive government support in many countries. In the US, PWR is applying for green stimulus money. Moore says: 'Because our technology is what is known as 'transformational' and 'shovel ready.' we should be eligible for stimulus funds. Those might come in the form of capital grants, project capital rebates or investment tax credits.'

In the UK, APP stands to receive two ROCs per MWh under the government's newly banded Renewables Obligation, but only for the biomass proportion of the feedstock it uses. 'Although there are other forms of financial support for the plasma gasification process in other countries, what makes the UK so attractive is the combination of the Renewables Obligation and landfill legislation that is increasing the tax on landfill disposal,' Merriweather explains.

The pool of companies focusing on this new technology is still relatively small but it is not hard to find other examples of promising start-ups with in-house technology, several of which have completed one or more funding rounds successfully. Alter NRG, a Canadian project developer using plasma torch technology, recently graduated from the TSX Venture Exchange to the Toronto Stock Exchange after a series of over-the-counter secondary offerings that raised more than $90m. Another Canadian company, VC-backed Plasco Energy Group (formerly RCL Plasma), has raised over $70m through private placements. While companies such as Europlasma and Alter NRG have commercially operating torch-based plants, graphite arc developers such as APP and PWR are yet to commission a plant. But this may not remain the case for long. PWR is starting up a demonstration plant at its headquarters in Alabama and APP is operating a small-scale pilot plant at its headquarters in Swindon, UK. The range of investment opportunities stretches from demonstration-stage, privately-owned technologies through to proven, publicly-listed IP-owning plant developers. While the newer technologies are not without significant risk, for investors willing to devote time to really understanding this sector the rewards could be substantial.

Plasma gasification: Harnessing the power of lightning

Customer comments

No comments were found for Plasma gasification: Harnessing the power of lightning. Be the first to comment!