An increasing number of private individuals supply excess electricity from bioenergy. Think of farmers who produce biogas from organic waste and use it in combined heat and power plants. They feed excess energy into the grid and take electricity back only when they need it. But when individuals use intermittent energy sources such as wind or solar, they face storage and transfer problems. The wind does not always blow, the sun doesn't shine all day. This is a major disadvantage of renewables that cannot provide baseload power.

However, Dutch-sponsored researcher Haimin Tao examined how this problem can be solved and found interesting parts of the solution. Electronics giant Philips has acquired a patent for a part of this system - a clear signal of its viability.

When efficient energy storage and grid-feeding products for intermittent renewables become available, the electricity grid of the future might begin to resemble an 'internet of energy', in which people become both consumers and decentralised producers, 'uploading' and 'downloading' electricity packages (previous post).

In a project funded by Technology Foundation STW, Haimin Tao examined the conditions such a good regulation system for energy transfer must meet. As the sources and storage elements vary considerably in terms of aspects such as voltage level, the conventional conversion technique needed to be improved. The search for improvements focused on soft switching, reduction of current amplitudes and a greater efficiency.

To safeguard the quality of the power flows, the researcher sought the appropriate regulators and storage systems so that the energy generated by external sources could be (temporarily) stored in suitable components, such as batteries and supercapacitors:

Eventually he arrived at a triple port system that rendered energy transfer between different sources possible. As the new triple port converter transforms the energy in a single step, it could be more cost effective, flexible and efficient than the conventional approach.

Philips, which participates in the STW users' committee for the research project, saw a marketable idea in the system. Following the testing of an experimental system, a patent was applied for and obtained. Philips might use the patent for future products.