History in the making at Schwarze Pumpe1 October 2008
The day that the world's first fully realised oxyfuel boiler demonstration facility was formally inaugurated at the Schwarze Pumpe power station may well turn out to have been a key moment in industrial history. Owner Vattenfall is reckoning on gaining a significant lead in a technology that may solve two problems at a stroke – how to turn Europe’s plentiful coal supplies into power while cutting its CO2 emissions.
Attendees at the ceremony on the ninth of September when the world's first oxyfuel boiler was formally inaugurated at the Schwarze Pumpe power station in north-east Germany may have been present at a key moment in industrial history. Dignitaries including Germany’s secretary of the Chancellery, Thomas de Maizière, the prime minister of Brandenburg, Matthias Platzeck, and Swedish minister for Higher Education and Research Lars Leijonborg were among those who witnessed the formal start up of a plant that is a pilot project for commercial carbon capture and storage and aims to be the first coal-fired plant in the world to capture and store its own CO2 emissions.
Oxyfuel combustion aids CCS by creating an exhaust with very high carbon dioxide content from which the other pollutants can readily be separated. Separated CO2 is then pressurised to one 500th of its original volume and, in the fully mature plant, transported to a gas field where it will be stored 1000 m below the surface in porous rock caverns. The pilot unit, which has a thermal capacity of 30 MW, was constructed over the last 15 months at the Schwarze Pumpe plant premises in the Lausitz region in the State of Brandenburg. For the operator Vattenfall, which funded the r70 million project itself, this moment will be the culmination of two years hard work in getting the pilot running. It is gambling on gaining a significant lead in a technology that may solve the problem of providing energy security in Europe through burning the continent's plentiful coal supplies while avoiding the CO2 emissions that cause climate change.
But with such an expensive and as yet not fully proved technology there are big questions still to be answered, particularly over where CO2 will be stored and whether or not customers will be willing to pay the high costs of building and running CCS plants. Vattenfall considers that it is essential that the technology gains acceptance by the general public. There is also a need for financial and political support and for a legal framework for CO2 storage.
The EU wants to see twelve full-scale power plants demonstrating CO2 capture in operation within the next few years. But although several other firms are planning pilot projects, no full-scale CCS coal plant has yet been commissioned and questions over CCS funding in Europe remain as yet unresolved by the European Commission and the European Parliament.
The British government has promised a decision in October on how it will fund a full-scale CCS in the UK, but it has few options (other than simply billing the taxpayer). The options include introducing new rules compelling all coal plants to fit CCS – (industry and the consumer will pay), direct funding from the EU or member states (unlikely – member states do not want to pay), a feed-in tariff, creating a new fund within the EU's Emission Trading Scheme which would give firms valuable carbon credits for every stored tonne of CO2 (this would cost nothing but might shake the CO2 market) or setting a CO2 emission limit for all new power stations.
The goal of the CCS project
Given that fossil fuels will be in use for power generation for some time to come, and that emissions need to be cut drastically before the development of alternative energy sources can cut in, CCS becomes a plausible concept to help achieve a sharp reduction of carbon dioxide emissions from such plants. It can support the transition to a long-term sustainable energy system and be one step on the way to fossil fuel independence.
Vattenfall’s project aims to provide commercially-available CCS technology by the year 2020. The plant should be able to capture more than 95 % of the carbon dioxide in the flue gas. To this end the company intends by 2015 at the latest to construct two demonstration power plants with an electrical capacity of up to 500 MW. From 2020 onwards the technology should be economically viable and available for large-scale industrial applications.
Vattenfall has been working since 2001 on developing methods for capturing CO2 from large coal-fired power plants and storing it underground. There are three main technology options applicable to large power plants – oxyfuel combustion, where CO2 is practically the only product of combustion in almost pure oxygen and recycled flue gas; post-combustion, where CO2 is washed from the flue gas after conventional combustion; and pre-combustion, where a gasification process removes the carbon from the fuel before the resulting hydrogen is combusted.
CCS pilot at Schwarze Pumpe
The existing Schwarze Pumpe power station located in Brandenburg is a 1600 MW double block lignite plant . It burns raw lignite from the Welzow-Süd open-cast mine. When operating at full capacity, it uses 36 000 tonnes of lignite daily. To treat flue gas the plant uses a combination of measures – low-NOx combustion, flue-gas de-dusting and flue-gas desulphurisation, to keep the plant operating comfortably within legal limits.
The 30 MWt pilot plant using CCS technology and a boiler developed by Alstom is connected to one of the existing units. The purpose of the pilot plant is to validate and improve the technology relating to the oxyfuel method of capturing CO2. So far, this technology has only been tested on a smaller scale. Vattefall began performing tests at Schwarze Pumpe during the summer of 2008. A wide range of tests will be performed at the pilot plant during a first test period of three years.
The concentrated carbon dioxide from the pilot plant will be injected for permanent storage in a gas field in Altmark in northern Germany.
In the pilot plant, the technology itself and the process will be validated. The next stage, a demonstration plant forming the link between the pilot plant and a fully-developed commercial concept, will attempt to demonstrate the commercial fitness of the technology. Initial studies for demonstration plants have already begun within Vattenfall and two sites have been chosen so far.
In northern Denmark, it is investigating the possibility of storing CO2 at the Vedsted structure, a geological reservoir between one and two km below ground level. If the site proves suitable for CO2 storage, the Nordjylland power station will be equipped with a full-scale unit for CO2 capture using post-combustion techniques. The carbon dioxide will be transported through a pipeline across the 30 km between the plant and the storage site. The Nordjylland demo could be ready and operational by 2013.
In Germany, the Jänschwalde power facility will be converted into a demonstration plant. Parts of the existing plant will be equipped with units for CO2 capture and Vattenfall is currently investigating the possibilities of implementing both oxyfuel and post-combustion technology at Jänschwalde for realisation in the year 2015. It has not yet been decided where the captured carbon dioxide is to be stored.
Transporting liquid CO2 presents a difficulty in itself. A single 1600 MW lignite-fired power plant like Schwarze Pumpe produces around 10 million tonnes of CO2 each year. Transport through pipelines or by ship are the most suitable alternatives for such large amounts of CO2.
In many parts of the world, natural carbon dioxide is found in geological formations where it has been trapped in sedimentary rock types in much the same way as oil and gas. The intention is to make the conditions for geological storage resemble the conditions in these natural CO2 storage sites. Depleted oil and gas fields have demonstrated an ability to hold oil and gas over millions of years, which argues well for their potential to function as long-term storage sites for CO2. Another alternative is to inject CO2 into active oil and gas fields to enhance the extraction of oil and gas by making possible the recovery of low pressure remnants.
There are also geological formations that are filled with salt water that can be suitable as storage sites. CO2 partially dissolves in salt water and can under certain conditions react slowly with dissolved minerals and form carbonates.
Regardless of the option that is selected, the storage site would be covered with an impermeable layer of rock, known as cap rock, that prevents leakage. When the storage site has been filled, it would be permanently sealed and kept under constant surveillance.
External climate campaign
The project has aims over and above its commercial requirements, according to the company’s CEO Lars G Josefsson. It helps support a general move toward climate change initiatives, of which he is a passionate supporter and for which an active campaigner.
The first and primary aim is to enable a global price to be put on carbon dioxide emissions, which Josefsson sees as the key to financial backing for a free market solution to the climate change crisis. It is also the key aim of the 3C initiative (Combat Climate Change), supported by Vattenfall, which he was instrumental in creating in 2007.
The second is to provide more support for climate-friendly technologies, and the third, to implement climate requirements on products. The overall objective is to encourage people to take an active interest in climate issues, showing that they can actually have an impact on developments in this area and to highlight what Vattenfall has been and is currently doing over the course of the last several years regarding climate issues, and to this end a ‘climate programme’ comprising many activities is already taking place throughout Europe. Part of this will be a number of future-oriented events, nationally and locally, on the theme of energy and the climate, and celebrating at the same time the company’s hundredth year of existence.