As the twenty-first century begins, Americans are torn by two conflicting motives when it comes to energy:They want secure energy, and they want to protect their environment. As a result they want to reduce reliance on fossil fuels, because so much oil is imported and because fossil fuels have substantial environmental impacts.

At the same time, fossil fuels remain plentiful. Prices, although sometimes high, appear to be well within the budgets of most Americans. Few people and few companies are motivated to seek out different fuels for the short term.

And even if alternative renewable fuels were competitive in price, the evidence suggests that there is no single "environmentally correct" fuel. All fuels have their strengths and their weaknesses. Perhaps the most that can be said confidently about energy in the next decade is that alternative fuels...