malmkvist runs the power grid for bornholm, an island of 40,000 people off the coast of denmark.island's electricity consumption is fairly predictable. >> you can see people get up in the morning about half past five. then they go to eat, and then they just stop. >> reporter: but the island's electricity supply is becoming less predictable. like most places, bornholm used to get most of its power from coal and gas, but now more than half comes from wind and solar, which fluctuate constantly. >> you can see the wind. it goes suddenly up and down all the time. >> reporter: as denmark adds more renewable energy, that mismatch between when electricity is being produced and when it's needed is a growing problem. but this sleepy fishing island is home to a cutting edge energy experiment that could make the variability of wind and solar less of a problem. bornholm has branded itself the "bright green test island," and welcomed a series of futuristic experiments focused on the electric grid. the most ambitious experiment is called ecogrid e.u.. at the demonstration house, project leader