Casting about for some small thing you can do to be environmentally responsible? You can always disconnect your doorbell. So says David de Jager, an energy and environmental consultant with E-Concern in The Netherlands (part of a larger organization called ECOFYS). He opened his Tuesday morning presentation by pointing out that an electrical doorbell is pretty much hooked up all the time and therefore draws about 5 watts continuously year-round -- more if it's lit up, and when someone presses it.

This works out to something like .01% efficiency, according to de Jager. In fact, the power required to connect all the doorbells in Europe is equivalent to the power output of two coal-fired power plants, all for a convenience we barely use. Quoth de Jager: "This is idiotic." Especially for those of us who don't receive many visitors.

De Jager's actual presentation had little to do with the doorbell anecdote; that was just his way of emphasizing that the first step in resolving the global energy challenge is to start reducing energy needs, and even seemingly minor things we take for granted can, collectively, add up to a significant amount of wasted energy. he was really there to talk about E-Concern's POSEIDON project. E-Concern's stated mission is "A sustainable energy supply for everyone," and as its name implies, POSEIDON looks to the seas to find that sustainable supply.

Advocates of solar energy like to point out that the sun deposits some 174,000 TW of energy every day onto our humble planet, with 95,000 TW reaching the earth's surface, of which seas and oceans cover over 70%. Of that, 3,600 TW are converted into winds and tides (the latter amounts to about 3 TW). That might not seem like a large percentage of the total, but annual global energy consumption amounts to about 16 TW. The way de Jager tells it, roughly 9% of the North Sea area could supply all of the North Sea countries with electricity by 2030.

In theory, of course. Figuring out how to harvest that raw energy and convert into usable electricity at low cost -- and in a sustainable way -- is the hard part.

The oceans already play a critical role in the global energy supply, since a large fraction of oil and natural gas is extracted offshore. The POSEIDON plan calls for using existing oil and has platforms and infrastructure, combined with carbon capture and sequestration capability to achieve "a carbon-free electricity supply" for the North Sea region. The heart of the POSEIDON concept is the construction of an offshore electricity transmission grid connecting onshore user regions with each other, and with offshore fossil and renewable electricity production and storage technologies.

For all his optimism, de Jager's a smart man, and a realistic one. He knows there are drawbacks to this proposition. There are definitely higher costs associated with wind and tidal energy sources, certainly at the outset. De Jager counters that locating the platforms so far offshore means higher wind speeds and thus higher energy production. He thinks production costs could be as little as 12 to 16 cents per kW/hr, dropping below 10 cents per kW/hr once the system is fully operational.

Then there's the fact that the platforms are located so far out to sea translates into higher risks. Q7, the offshore wind project currently under construction in the North Sea -- and a $540 million investment -- has already experienced delays after a cable broke during harsh weather, although no workers were injured. Can POSEIDON's offshore turbine platforms withstand gale-force winds during major storms? Maybe -- they're certainly figuring that possibility into their designs. Q7 will be an important test case.

It's tough to tame Mother Nature. Things like tides and winds can be difficult to predict and control. What happens if there is no wind for significant periods of time? Some sort of back-up energy supply is required. That's why POSEIDON emphasizes an integrated systems approach. "Production, conversion and transformation, transmission and distribution, storage, and final energy demand are not separate elements, but must be considered from a system perspective," said de Jager.

The offshore platforms and using carbon for enhanced oil recovery are just the initial phase of POSEIDON. In the mid-term, the plan is to develop technologies to draw energy from ocean waves, as well as ways to store that energy until it's needed. E-Concern has a prototype device called the Wave Rotor to convert wave and tidal energy into usable electricity. Long-term goals include incorporating truly innovative approaches to harvesting energy from wind and water: biomass (extracting energy from sea organisms like algae), osmosis (extracting energy from chemical differences in sweet and salt water), ocean thermal energy conversion, tidal energy extraction, and large-scale carbon capture and sequestration. Eventually all those technologies will be interconnected to ensure a clean, safe, stable and reliable energy supply. Also a cheaper one, since the interconnectivity should reduce system costs.

That's the plan, anyway. Much work needs to be done to make it a reality, right down to designing improved wind turbines that use direct drive (no gear box), have larger capacities (15 mW compared to today's 4.5 mW), and more robust carbon fiber blades. New concepts for transmission and transport must also be developed to fully achieve POSEIDON's mission of cheap, clean, sustainable energy for all. That add ups to a whole lot of R&D, and at the moment, there aren't too many researchers working on those areas.

De Jager's youth and enthusiasm are infectious, but I couldn't help wondering if his enthusiasm for wind energy was related to the fact that he's Dutch. That's a region with a history of drawing power from wind and water, and ample natural resources to make schemes like POSEIDON possibly viable. It drove home a point made by an earlier speaker, MIT's Milly Dresselhaus: the global energy crisis in international in nature, and different energy solutions will be desired by different geographical regions, depending on the resources available to them.

While we're waiting for new technologies to save the world from itself, feel free to do your small part ands unplug your doorbell. And how about unplugging all those battery rechargers for your cell phone, laptop, PDA, etc., if you're not actively using them? They belong to the category of "vampire appliances" because most of the energy (95%) is wasted if you leave the charger plugged into the wall, but not into your phone. Nokia even issued a public service announcement to that effect this past May. If 150 people did this for one year, they would save 1 ton of CO2 that would otherwise be emitted into the atmosphere. Little things can make a difference, when done collectively.