Technologies of the future

CO2 capture will contribute considerably to the district heating supply of tomorrow

“When oil and coal pollute our planet, we need to develop better energy sources. Large windmill farms rise at sea and convert nature’s mighty forces to the benefit of all of us. More is on the way, e.g. “green” fuels for aeroplanes and vessels and ambitious proposals for carbon capture and underground storage.”

In her New Year's Speech on 31 December 2021, the Danish Queen addressed the need for a quick acceptance of new technologies for the benefit of all of us. The concrete and very technological message probably came as a big surprise to many Danes. Many within the technical environments and circles have known about the idea of capturing CO2 for many years, however, the subject of CO2 capture has suddenly become a common subject which we all need to relate to.
CO2 capture – also called Carbon Capture (CC) – is considered an extremely important instrument: Cap-turing CO2 will contribute to solving one of the biggest climate challenges in the world as the capture will reduce the total amount of CO2 in the atmosphere. Therefore, technology is considered to be one of the tools which can contribute efficiently to the reduction of global warming. 

CO2 is not CO2

In CO2 accounts they distinguish between CO2 from fossil sources such as coal, oil, and natural gas. This also includes CO2 from plastic and petrol. At the other end we have CO2 from biogenic sources such as wood, straw, and potato peels. Even though CO2 is CO2, we differentiate between the type which is al-ready rotating between plants and the air (biogenic) and all the other types we add to the atmosphere by digging or pumping it up from the underground (fossil). 

IPCC, the official definition of UN's Panel on Climate Change, is that sustainable biomass is CO2 neutral. In practice, this means that energy originating from burning straw or sustainable biomass in the form of wooden pellets and wood chips are CO2 neutral; the energy originates from biogenic sources.

Negative emission

Moreover, they operate with negative emissions. If the biogenic CO2 originating from biomass is captured and deposited, it generates negative emissions. In short, more CO2 is absorbed and stored than emitted. We can also remove CO2 from the atmosphere. It is because that biomass comes from a closed carbon cycle at the earth's surface where trees absorb and emit CO2. However, CO2 capturing must not recognise the emission of CO2 – in general, the global goal is to limit our emissions.
VEKS’ interest in CC is two-prong. VEKS both has focus in general on the reduction of CO2 emission and an interest in utilising the surplus heat produced in connection with CC.

New technologies at Avedøre CHP Plant

Various energy companies in the Greater Copenhagen area already cooperate with respect to the new technologies, CC (Carbon Capture) and PtX (Power-to-X). This takes place in VEKS’ supply area – at first, in the straw-fired boiler at Avedøre CHP Plant. Here, VEKS, CTR, Ørsted and HOFOR work together on two parallel development projects which will contribute to the green transition by testing technologies of the future.

System integration between the electricity, transportation and district heating sectors are thus realised by way of specific development projects.

Straw goes mono

In 2021, Ørsted, CTR and VEKS agreed to rebuild the straw-fired boiler at Avedøre CHP Plant so it could operate in mono – i.e. independently of the main boiler in unit 2 at Avedøre CHP Plant. The reconstruc-tion will be ready in late summer of 2022. With the mono-operation-straw-project you will be able to connect the heat production of the straw-fired boiler separately to the transmission system by inserting a heat exchanger. In this way you can avoid regularly starting/stopping the large biomass-fired main boiler when the heat demand is fairly small. A more efficient and constant operation will reduce the owner’s servicing expenditures – and thereby also reduce the heat purchase costs of CTR and VEKS. Moreover, the lifetime of the boiler will be prolonged. 

Two projects at Avedøre CHP Plant

As already mentioned, Ørsted, CTR and VEKS are behind the project of capturing CO2 in the straw-fired boiler of Avedøre CHP Plant. Ørsted owns the chimney and the heating companies are to utilise the sur-plus heat. 
Captured CO2 can either be stored in the underground or by isolating the carbon of the CO2 and utilise it in a PtX process. If hydrogen is used together with the carbon capture from the chimney in the PtX pro-cess, it is possible to produce liquid fuel. And this is exactly what the Green Fuels for Denmark project is going to do when it comes to producing e-methanol and e-cerosin for shipping and aviation, respectively. The heavy transport requests green liquid fuels as it is not possible to “make do with” electricity or bat-tery in many cases. 

Surplus heat

For the two heating companies, CTR and VEKS, the CO2 capture and PtX are primarily about taking ad-vantage of the surplus heat in the two technology processes. CO2 capture and PtX involve large amounts of surplus heat. Therefore, a requisite for developing the new technologies is also that the processes take place close to the large, existing district heating systems, e.g. the transmission systems of CTR and VEKS.
The forthcoming, detached straw-fired boiler will play an important part in Ørsted's Power-to-X project Green Fuels for Denmark which is expected in course of time to reach a total capacity of 1.3GW and have a CO2 reduction potential of 850,000 tonnes per year.

Production of sustainable fuels takes place in the PtX process where carbon, as mentioned before, from the CC process is combined with hydrogen. Electricity, e.g. from windmills and solar power cells, may segregate hydrogen from water by way of electrolysis. Hydrogen can be used directly as fuel in the in-dustry, trucks, buses, etc.
HOFOR will only contribute renewable energy to the PtX-project Green Fuels for Denmark by way of wind power electricity from HOFOR's planned 250MW large offshore wind farm Aflandshage in the Baltic Sea. The current wind power electricity will be supplied directly from Avedøre CHP Plant.

The parties agreed that it was most obvious to establish CC at the Avedøre CHP Plant’s straw firing plant as source for delivering sustainable CO2 to the next stages of the Green Fuels for Denmark project. 
As far as VEKS is concerned, the participation in the development projects will contribute to reducing the total CO2 emission. At the same time, the projects will mature the technologies to the delight of the en-tire energy sector and the surplus heat will contribute considerably to the district heating supply of tomorrow.