Last week Denmark's minister of energy introduced new legislation that may extend solar PV development further. In what appears to be a net-generation feed-in tariff, the minister proposes that Denmark pay DKK 1.30 ($0.22 USD) per kWh for excess generation from solar PV systems less than 6 kW. The bulk of self-generation will offset the Danish retail price of electricity, the highest in Europe. This could extend Denmark's solar boom.

Among the markets selected, the US leads only China in solar PV capacity per capita.

Wind

The US fares better in wind than in solar PV, but it still lags many countries particular the true leader in wind: Denmark.

When California faltered in the late 1980s after the first tax-credit driven "wind rush", Denmark — and Northern Europe in general — picked up the mantle of leadership in wind energy development both in absolute terms and in capacity per capita.

Denmark operates nearly five times more wind capacity per capita than the US and a majority of that is owned by its own citizens.

Spain has installed more than three times as much wind capacity per capita as the US.

Installations per capita in France are behind those in the US. Nevertheless, wind in both countries face similar obstacles. As in the US, an unstable policy environment in France threatens continued growth of wind energy.

Wind was seen as a threat to incumbent state-generator Electricité de France (EDF), consequently former President Sarkozy place onerous new restrictions on wind development. Only 250 MW of new wind capacity was installed in France by mid-year, half of that typically installed.

The new government of Francois Hollande has yet to put their stamp on renewable energy policy and instead have deferred action until a "national debate" on energy is completed. If Hollande chooses a rapid development path, France could surpass the US in installed capacity per capita. If Hollande doesn't take corrective action soon, France will likely miss its 2020 renewable targets.

Geothermal

Though the US has the most installed geothermal generating capacity in the world, it still substantially trails many countries in capacity per capita.

Iceland remains in a class by itself with nearly 200 times more geothermal capacity per capita than the US.

New Zealand, one of geothermal energy's pioneers, remains a leader with 14 times more geothermal per capita than the US.

Biogas

Biogas remains the renewable energy technology most under appreciated in the US.

Industry analysts and renewable policy advocates alike often overlook biogas because the technology isn't seen as "sexy" as solar PV or wind. Yet in Germany, biogas alone will generate more than 20 TWh this year. That's as much as all of Germany's famed solar PV produced in 2011.

With the exception of dairy farmers in New England and the Midwest, there has been very little development of biogas generation in the US compared to Europe in either absolute terms or in capacity per capita.

German farmers operate nearly 200 times more biogas capacity per capita as American farmers. Austria operates 60 times more biogas capacity per capita as the US.

In conclusion, the US lags many of its peers internationally in the development of renewable energy technologies.

While the boom in US solar PV installations in 2012 is good news for the American renewable industry, the development of geothermal and biogas remain stalled relative to the success seen in other countries. Worse, the failure of Congress to extend the federal tax-credit for wind energy has caused the market for wind in 2013 to collapse.

Rather than leading renewable energy development, the US is in danger of slipping further behind its peers.

As President-elect Obama weighs how best to tackle climate change in his second term, and as Congress grapples with the budget and "entitlements", maybe now is the opportune time for the nation to consider sweeping revision of its renewable energy policies that go well beyond traditional tax subsidies and Renewable Portfolio Standards. It could well be the time for the US to consider a comprehensive suite of policies that have worked so well elsewhere.

These policies, for example, can be found in Germany's Renewable Energy Sources Act. This law grants all renewable generators the right to connect to the grid, the right to be paid for their electricity, and — most importantly — spells out how much they will be paid and for how long.

Most of the jurisdictions leading in renewable energy development worldwide incorporate these principles within their renewable energy policy in one form or another. Maybe it is time for the US to do so as well.