This paper explores the potential match (and some mismatches) between variable renewable power production and a range of demand-side resources, including demand response, demand-side storage and peak load- (or renewable nadir-) coincident energy efficiency. To understand the potential contributions and limits of the demand-side resources, and explore strategies to blend them in integrated resource portfolios, we study a range of renewable integration challenges. We characterize the renewable integration problems in terms of under-generation (too little wind and solar resource relative to load), over-generation (too much wind or solar resource relative to load), and ramping rates (too fast a change in load net of renewable production). We explore the time dynamics of energy available from demand-side resources and evaluate their potential for balancing variations in load and renewable output.