HISTORY OF DANISH POWER INFRASTRUCTURE
Denmark's current power grid was shaped by two significant political drivers. First, recognizing the inevitable end of north sea oil in the early ‘70’s and second, the discovery of large natural gas deposits in the north sea. Denmark decided to build a natural gas infrastructure throughout the country to wean Denmark’s power infrastructure from its dependence on coal and oil. This federal project was the largest investment ever in the history of Denmark. For this reason, municipal codes were rewritten to incorporate requirements to run power plants on natural gas. The existing power plants were coal and many still use coal and were modified to also run on gas.
http://www.ens.dk/en-US/supply/Gas_supply/Sider/Forside.aspx
In the years preceding these decisions the country experienced rapid growth in GDP and population. After years of heavy fertilization of farm lands, leaking land fills and inadequate industrial waste water treatment, the country was facing a significant water pollution problem. This led to a change in leadership. In the 80’s, Prime Minister Anker Henrik Jorgense was ousted and a conservative, Poul Schlüter, stepped in and took a strong stance on the environment. Under his leadership, Denmark subsidised development of the wind power infrastructure – another historical investment in Denmark that shaped the codes of the 90’s.
Industry also played a hand in shaping the face of power production in Denmark today. Kaldunborg is a port town northwest of Copenhagen on Zealand. Community and industry leaders there formed a partnership to take advantage of heat, water and other bi-products from municipal power production. The diagram below shows how the construction industry, bio-tech industry and shrimp farmers were able to create a circuit of shared resources to boost efficiency thereby saving energy and money.
INDUSTRIAL SYMBIOSIS VIDEO
DONG Energy runs the Kalundborg plant and most plants in Denmark. They boast much higher efficiencies at some of these plants by using strategies similar to those used in Kalundborg. The Avedøre plant in Copenhagen, for example, is capturing the fly ash from the coal power production and selling it to the construction industry for use in making concrete. Gypsum is also collected and sold to a local wall board manufacturer.
Other plants throughout the country are burning organic matter (municipal waste, wood waste, etc.) These plants are impacting the efficiency significantly by using the low pressure steam for district heating of homes surrounding the power plant.
DONG Energy Power Plant Video
Avedøre Power Plant video
WIND POWER IN DENMARK
The wind power now accounts for nearly 20% of the power required to run the country. The Horns Rev off shore farm pictured above is made up of 91 turbines and is capable of generating 209 MW of power. http://www.ens.dk/EN-US/SUPPLY/RENEWABLE-ENERGY/WINDPOWER/Sider/Forside.aspx
An interesting thing about power I didn’t realize is that you must use whatever you produce. Power demand over a 24 hour period fluctuates considerably. From a base load between 24:00 (midnight) and around 06:00 the demand climbs in the morning as industry warms up, people brew their coffee and dry their hair. By 09:00 the demand climbs to a daytime base load that is double the night time base. The end of work day shows a dip as industry slows then a climb in demand when individuals go home, flip on the TV and heat their frozen dinners. The demand falls through the evening returning to the base night time demand at midnight.
The infrastructure is designed to bring additional load online as it is required then shut it off again. Wind by its nature is unpredictable. It cannot be turned on and off to handle the peaks and valleys of daily or monthly demand. Wind is best utilized for managing one slice of the base load demand. This aspect of wind power generation is important to understand, because it means that the total power infrastructure can never be 100% wind. At 20% Denmark will look to other renewable sources to meet a total domestic renewable energy production target of 33% by 2020.
So what happens when you have a calm day? When the wind suddenly stops blowing you need another system to replace this load and it needs to start fast and replace all the power that wind turbines provided during the day.The power plants in Denmark are capable of generating between 50MW and 500MW of power. They are similar to the coal fired plants all over the US. They run on big turbines that take days to warm up and cool down so can't suddenly take on this new load. Wärtsilä is a company that makes smaller scale turbines (among numerous other things) that can be online much faster and run more efficiently than these large plants. These types of plants are necessary to balance the peaks and valleys of a wind farm. Page 9 at this link shows one such fluctuation at a Colorado wind farm. http://www.cleanenergycongress.com.ar/es/docs/pdf/6-%20Niklas%20Haga.pdf
The opposite scenario creates an interesting dilemma too. When the wind is turning the fan blades at their peak performance, wind farms sometimes produce more power than is needed. In Denmark, when this happens, they have to dump it to Germany and they pay them to take it. Wind power as a reliable renewable energy needs careful consideration. The cost for making the power is 10 times that of making a gas, coal or oil powered plant. CO2 and green house gases have to be a part of the conversation in order to make wind a viable solution.
