A New Jersey-based wind energy company plans to invest $42 million to build a 20-megawatt wind farm in Carroll County, The Des Moines Register reported. NJR Clean Energy Ventures, a subsidiary of New Jersey Resources, announced Wednesday that it has agreed to acquire its second onshore wind project on 1,100 acres in the county. MidAmerican Energy Co. will sell the energy produced at the Carroll County wind farm under a 25-year power purchase agreement with NJR, which will own and operate the wind farm. NJR said it will contract with Mortenson Construction for the project, which is expected to be in operation by spring 2015.