African nations still rank at the bottom in terms of human well being and development, but 2011 brought at least one reason to hope change is coming: a massive investment in renewable energy.

Total spending on wind, solar, hydro and other clean-energy development in Africa shot up to $3.6 billion last year — more than four times as much as was invested in 2004 ($750 million), according to Nigeria’s Bank of Industry. Even so, that growth lags behind renewables expansion on a global scale, where investment has increased more than six-fold, from $33 billion in 2004 to $211 billion in 2011.

Still, Africa’s clean-energy growth is encouraging news, especially in light of the fact that more than 600 million people on the continent — including 70 percent of the sub-Saharan population — don’t have access to electricity, according to figures from the United Nations.

It also appears that renewables development in Africa is likely to continue on a fast track: a 2011 report from Frost & Sullivan projects clean-energy investment will expand to $57 billion by 2020. That’s almost 16 times more than was spent last year.

You’ll find more details on the specifics — spending by energy source, potential obstacles, etc. — at Oil Price in a new post that explores the continent’s growing potential for renewable-power development.

• Africa’s faces “ecological deficit”