By Isla Binnie and Andres Gonzalez MADRID (Reuters) – Oil major Shell and utilities Naturgy and Verbund are preparing binding bids to buy renewable energy assets in Spain valued at about 1 billion euros ($1.1 billion), three sources close to the matter told Reuters. Spanish fund manager Q-Energy is selling the portfolio, taking advantage of strong appetite among European energy companies feeling increasing pressure from investors and governments to tackle climate change. Competition for market share is intensifying as oil and gas companies set ambitious green targets, jostling with utilities a…