In a world with souring populations and evolving technology the need for reliable energy sources continues to grow. However the environmental impact of producing this energy through traditional methods has led us to seek out varied renewable sources in order to maintain a balanced energy mix.
The most advanced, and therefore most reliable, source of renewable energy is onshore wind turbines. These account for over half of all energy from renewable sources and come in many varying sizes and power outputs. Most developed countries will have some amount of wind turbines adding to their energy mix and it is the countries with the best wind resources that reap the most from their onshore wind industry.
However some of the best wind resources are to be found in the some coldest regions. Also due the nature of the climate of these areas population tends to be sparser which can also be a benefit for onshore wind projects. In Finland for example these favourable conditions account for over 70% of the countries onshore wind industry.
These strong winds and the cold climate they bring with them can have a detrimental effect on the turbines as they can cause a build up of ice which can disable the blades temporarily. On average this cuts power output by as much as 20% per year.
However as is the case with many burgeoning industries, when a problem arises solutions follow and this is also the case here. There are a number of methods that have been considered or are in use for the task of removing ice from the turbine blades including the passive solutions of coating the blades with a hydrophobic paint, spraying them with an active chemical, or even painting them black to maximise heat absorption.
Active solutions include those using mechanics such as controlled acceleration and deceleration of the blades to shake off any troublesome ice and several different thermal solutions including heating the blades from inside by either warm air or electrical coils or by using microwaves.
As well as the foremost reason of reduction in operations which in turn will impact generation income there is also a danger of falling ice endangering workers and farm animals below. Also the weight of the ice can cause an unbalance in the spinning of the rotors leading to potential long term mechanical issues.
Turbine manufacturers Vestas and Siemans both currently use thermal solutions however they have opted for differing approaches, heating the air inside the blades and heated elements inside the blades respectively.
Vestas use sensors, information collated in databases of long term turbine outputs, and their own algorithm, as well as a long range communication network to operate a stream of warm air inside the blades. However rather than detecting ice build-up they remedy the issue at the earliest opportunity possible by using their algorithm to measure several variables including temperature, humidity, wind speed, and turbine output. Should the conditions be low enough for the formation of ice and the turbine output reduces the system initiates automatically using their patented Vestas De-icing System (VDS).
“VDS will provide significant value to those who want to harness the potential of wind power in colder climates with icing risk, locations such as North America as well as the northern and central regions in Europe, areas previously not economically feasible due to the risk of ice affecting power production,” says Vestas Chief Technology Officer Anders Vedel.
VDS is fully integrated with all other Vestas control systems and is serviceable from within both the hub and the blade. It can also be triggered both automatically and manually allowing users to monitor control fully.
Having tested a prototype in Canada throughout 2013 Vestas confirmed it has a low efficiency cost of only 150kW in a 3.3mW turbine.
Siemans first approached the issue some time ago and began by collating data about their turbine’s operational capacity in extremely cold conditions in the mid-1990s. Two years ago they patented a heating mat which can be integrated into the blades of its turbines. The mat has no wiring however it is electrically conductive and is installed close to the surface of the blade. Like the Vestas system it can be operated remotely or on site to melt the ice and allow the turbine to continue to operate uninterrupted.
National grid systems are now finding solutions in how to cope with the fluctuating power inputs from renewable energy, and particularly onshore wind instillations. With the advent of new reliable systems ensuring that production remains at its highest operational capacity we can reap the benefits afforded to us from these reliable renewable sources. The demand for energy is not going to reduce so we must continue to seek out new ways of improving the technology we have. The systems above are a positive step forward; in the future I look forward to writing more successful innovations which assist us in providing all with clean renewable energy.