Cogeneration can double our energy efficiency

April 28, 2009
Energy Expert Peter Garforth delves into how cogeneration can double our energy efficiency.

It’s almost impossible to go anywhere and not see “green.” From the White House organic food garden to the solar panels on the local high school, everyone is tapping into a groundswell of awareness and rethinking of our energy value chain. The cynical me asks two questions. The first wonders how much of this greenness has to with stimulus dollars. The second is about scale.

The latter brings us to heat. Most factories need heat for processes and for workspaces. Every factory releases substantial amounts of waste heat. Every furnace, chiller, melter, compressor, oven, dryer, light, pump and motor generates unused heat. All factories use electricity, virtually all of which eventually becomes heat.

Electricity, this immediately available resource, is the source of massive pollution and wasted costs measured in the trillions. For some reason, it never seems to make it to the green dialogue in a meaningful way. Where are the environmentalists hanging banners on factory cooling towers as symbols of profligate waste?

As so often is the case, the devil is in the details. When a factory starts looking at its existing processes for heat-recovery potential, a common conclusion is that there is more waste heat available than potential uses for it. It makes sense to heat the warehouse and the workspaces and to run the domestic hot water systems from waste heat recovery. Doing this saves a few thousand dollars in oil or gas purchases, and gives experience in analyzing and using heat as a utility. We might even consider taking some lessons from the past and look at applications such as melting snow in common areas using heat arrays.

But these actions can be seen as Band-Aids, as they only stem the waste of heat from processes a hundred miles away from the factory, at the power plant where the electricity is generated. To put a quick scale on this, the heat wasted in the U.S. electric system is 7% of all energy used … in the world.

So, how can factories be green about fossil-fired waste heat? With existing plants, every possible measure to reduce local and remote heat waste must be considered, prioritized and executed. This requires a deep understanding of the uses and sources of heat around the site as a part of the overall energy balance mapping. There’s a need for openness and creativity in developing possible ways to bridge from a waste heat source to a heat use. Language can help. Calling a compressor an “electric boiler that also makes compressed air” might strictly be inaccurate, but it gets people thinking differently.

With new plants, focus on planning heat uses and their relationship to possible heat sources. Heat is a utility like any other. When it can be sourced from internal byproducts, operating costs and greenhouse gas risk exposure drop. At the same time, usually other process efficiencies are captured. Ask BASF. Through their “Verbund” approach to integrated chemical sites, they have some of the lowest operating costs in their industry. This approach to plant design started back in the early 1980s. It has evolved to where plant designers almost see a cooling tower as symbol of failure, not an inevitable necessity.

Heat produced at the power station must be considered. In a sane world, a lot of our green passion would be focused on enabling cogeneration (combined heat and power, or CHP) wherever it makes sense. To a first approximation, CHP doubles the fuel efficiency and radically reduces greenhouse gas emissions. Too often the barriers are sheer regulatory complexity and prohibitive statutory gateway costs with the local utility. These must be swept away now, starting with every state immediately recognizing clean electricity with at least 70% to 80% fuel efficiency as part of its Clean and Renewable Electricity Portfolio Standards, irrespective of size of the generating unit. Congratulations to the European Union for taking steps in this direction, and to Ohio and Ontario for considering this.

Finally, we must address sharing heat. With the best will in the world, even with outstanding design and distributed generation, a facility might still make more heat than it uses. We must find ways to look to the neighbor’s factory and find uses for our excess. For most companies, running their own business is enough and they balk at this step. Enter the industrial park with shared services, including electricity, natural gas, process steam, heating, cooling and compressed air managed as site utilities by an independent micro-utility. This isn’t a fantasy; it’s the operating reality in places like the Gersthofen Industriepark in Bavaria, taking the idea of waste heat recovery to a whole new level.

The world uses 450 exajoules annually, or 425 quadrillion Btu of primary energy. Even in slow times, we’re adding 1% to 2% per year to this number, the primary fuel equivalent of adding 300 power stations every year. Conservatively, 50% of this is wasted as unused heat. That should be a big enough opportunity to keep the “greens” up at night.

Peter Garforth is principal of Garforth International LLC, Toledo, Ohio. He can be reached at [email protected].

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