Denmark's powerful lessons for the future

It is possibly the most advanced, and certainly the most efficient, power station in the world -- and the statistics sound almost too good to be true.
Built in two distinct phases over the past 13 years, Denmark's Avedore power station utilises a staggering 94 % of the energy of its fuel, compared with between 40 and 50 % for the average electricity producing power station in the UK. It burns coal, gas, oil, straw and wood pellets, and is equipped with a range of cutting-edge technology to reduce harmful emissions into the environment and meet Kyoto protocol targets to limit climate change. In addition, the heat produced in the process of generating power is used to heat 190,000 homes in Copenhagen through a network of pipes which run through the city.

Surprisingly, this most modern of power generating plants at Koge harbour in south Copenhagen, owes its existence to the oil crisis that gripped western nations in the 1970s. Electricity blackouts that have hit the UK, Europe and North Americain recent months have made security of supply a key issue. But they have also served as a stark reminder of the energy crisis of three decades ago, when oil price hikes, brought about by Middle Eastern oil producers in the OPEC cartel, sent western industrial economies into a tailspin.
Rising prices stimulated piecemeal conservation efforts in the west -- and, more importantly, a determined and unprecedented exploration for new oil resources. When these were inevitably discovered, the increase in supplies and declining demand saw oil prices fall from $ 35 a barrel in 1981 to $ 9 a barrel in 1986.

Things then carried on as they had done prior to the crisis, and the queues at petrol stations, shared baths, power cuts and cold, lamp lit suppers became just a distant, foggy memory. The chances of such crises occurring again were too slim to be taken seriously. In Denmark, however, the episode had left a more lasting impression and heralded the defining moment of the country's energy policy which is still benefiting its people today.
In the aftermath of the energy crisis, members of the Folketinget (the parliament) decided every new plant built in the future must be a combined heat and power (CHP) station, and be linked in to the district heating (DH) networks that now serve the majority of Danish cities.

In addition, legal measures were implemented that allow local authorities to force building owners to connect, and remain connected, to DH. Fossil fuels were subjected to high taxation for heating and investment subsidies were offered to the utility companies to update and complete DH networks.
Hans Kristoffersen, an energy policy and economics adviser with the Confederation of Danish Industries, said: "The oil crisis in the 1970s was what really led to the policy and realisation that we needed to use energy more efficiently and that led to an increased focus on DH. We now have several hundred CHP plants, many of which really took off in the 1990s, and the concept of Avedore follows that philosophyin creating electricity as well as serving the DH network of Copenhagen, along with all the other plants."

Avedore is essentially two power station units combined: Avedore 1, built in 1990 at a cost of £ 190 mm, and Avedore 2, operational at the end of 2001at a cost of £ 380 mm. The Avedore 1 unit can also cope with oil combustion to increase its flexibility, but primarily burns approximately 85 tons of coal every hour. It produces 250 MW of electricity, serving some 400,000 households and 330 MW of district heat for 80,000 houses.
Despite burning one of the dirtiest fossil fuels, it thoroughly removes ash, sulphur, nitrogen and carbon dioxides from the flue gas, a process which produces 3.5 tons of gypsum and mineral products which are then used in the cement and building industries.

Avedore 2 is capable of using oil and natural gas, but primarily uses wood pellets and straw. The wood pellets are made from surplus wood from Junckers, the world's largest manufacturer of hardwood flooring. As such, they are totally CO2 neutral and the 300,000 tons burnt annually make up half of the fuel used at Avedore 2.
This is connected to a separate unit, the world's largest straw-fired boiler -- that can supply the turbines with additional steam. It burns 150,000 tons of straw a year, accounting for 10 % of Avedore 2's fuel consumption, is also CO2 neutral, and all the ash is returned to the fields where it was grown for its fertiliser value.

Together, each of these units supplies steam which operates large generators producing electricity for the grid. When the driving force of the steam has been utilised, it is then directed to large heat exchangers where the heat is transferred to the DH water circulating in the grid. Finally, the steam is returned to the boilers where it is supplied with new energy before the process is repeated.
Avedore 2 generates 570 MW of electricity, meeting the needs of some 800,000 households and the same amount of heat for approximately 110,000 homes.

If both the heat and electricity capacities of Avedore 2 are added together, it has a similar generating capacity to Cockenzie coal-fired plant, in East Lothian, which was recently named as Britain's worst polluter in terms of carbon emissions. The main difference between the two is that most of the heat produced at Cockenzie is lost without any energy being reclaimed, vastly reducing its efficiency of fuel use.
CO2 emissions for Cockenzie in 2002 were 4,138,000 tons, compared with 949,347 for Avedore 2. Add to this the fact that the lion's share of fuel used in Avedore 2 is carbon neutral (in that it is produced from plant material which takes up carbon dioxide from the atmosphere as it grows) and it quickly becomes apparent just how inefficient Cockenzie is in comparison.

ScottishPower, which runs the plant, accepts it produces relatively high emissions of CO2, but points out that this is only because they are operated occasionally as back-up power stations rather than continually as base load stations. However, electricity produced by the Avedore plant is expensive.
Although Energi E2, the company which owns the plant, will not specify the exact unit production price of electricity and heat per kWh due to commercial sensitivity, it does give approximations. For coal it sells at £ 0.012 per kWh, for gas £ 0.023 per kWh and for oil £ 0.028 per kWh, giving an average of £ 0.021 per kWh including the biofuels price.

Compare this with nuclear and it is perhaps understandable why Britain has not gone down the road of multi-fuel plants and CHP -- British Energy, the nuclear power generator which provides a fifth of the country's electricity, sells at £ 0.015 per kWh.
However, although nuclear power has consistently been marketed as a cheap, and CO2 -neutral, electricity-generating source since its introduction, the actual costs fail to take into account the hugely expensive process of nuclear waste management and constant subsidies thrown at the industry by government -- all from the public purse.

Between April and the end of August, British Energy reported unaudited operating losses of £ 40 mm. This does not include the £ 3.3 bn subsidy promised by the government over the next decade for nuclear waste management, or the losses made by shareholders and bondholders as part of the restructuring, or the various other subsidies such as local authorities agreeing to delay rate payments, and various creditors freezing payments.
Peter Roche, a campaigner with Greenpeace, said: "CHP, like wind power, is a classic case of British procrastination. While we sit and ponder for years, the Danes get on and build systems which are now producing environmentally-friendly electricity, whereas we can't even decide what to do with our nuclear waste."